1
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Watkins NE, Diroll BT, Williams KR, Liu Y, Greene CL, Wasielewski MR, Schaller RD. Amplified Spontaneous Emission from Electron-Hole Quantum Droplets in Colloidal CdSe Nanoplatelets. ACS NANO 2024; 18:9605-9612. [PMID: 38497777 DOI: 10.1021/acsnano.3c13170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Two-dimensional cadmium selenide nanoplatelets (NPLs) exhibit large absorption cross sections and homogeneously broadened band-edge transitions that offer utility in wide-ranging optoelectronic applications. Here, we examine the temperature-dependence of amplified spontaneous emission (ASE) in 4- and 5-monolayer thick NPLs and show that the threshold for close-packed (neat) films decreases with decreasing temperature by a factor of 2-10 relative to ambient temperature owing to extrinsic (trapping) and intrinsic (phonon-derived line width) factors. Interestingly, for pump intensities that exceed the ASE threshold, we find development of intense emission to lower energy in particular provided that the film temperature is ≤200 K. For NPLs diluted in an inert polymer, both biexcitonic ASE and low-energy emission are suppressed, suggesting that described neat-film observables rely upon high chromophore density and rapid, collective processes. Transient emission spectra reveal ultrafast red-shifting with the time of the lower energy emission. Taken together, these findings indicate a previously unreported process of amplified stimulated emission from polyexciton states that is consistent with quantum droplets and constitutes a form of exciton condensate. For studied samples, quantum droplets form provided that roughly 17 meV or less of thermal energy is available, which we hypothesize relates to polyexciton binding energy. Polyexciton ASE can produce pump-fluence-tunable red-shifted ASE even 120 meV lower in energy than biexciton ASE. Our findings convey the importance of biexciton and polyexciton populations in nanoplatelets and show that quantum droplets can exhibit light amplification at significantly lower photon energies than biexcitonic ASE.
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Affiliation(s)
- Nicolas E Watkins
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kali R Williams
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Yuzi Liu
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Chelsie L Greene
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- International Institute for Nanotechnology, Paula Trienens Institute for Sustainability and Energy, Northwestern University, Evanston, Illinois 60208, United States
| | - Richard D Schaller
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- International Institute for Nanotechnology, Paula Trienens Institute for Sustainability and Energy, Northwestern University, Evanston, Illinois 60208, United States
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2
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Poonia AK, Mondal B, Beard MC, Nag A, Adarsh KV. Superfluorescence from Electron-Hole Plasma at Moderate Temperatures of 175 K. PHYSICAL REVIEW LETTERS 2024; 132:063803. [PMID: 38394562 DOI: 10.1103/physrevlett.132.063803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 01/12/2024] [Indexed: 02/25/2024]
Abstract
Superfluorescence, a cooperative coherent spontaneous emission, is of great importance to the understanding of many-body correlation in optical processes. Even though superfluorescence has been demonstrated in many diverse systems, it is hard to observe in electron-hole plasma (EHP) due to its rapid dephasing and hence needs strong magnetic fields or complex microcavities. Herein, we report the first experimental observation of superfluorescence from EHP up to a moderate temperature of 175 K without external stimuli in a coupled metal halide perovskite quantum dots film. The EHP exhibits macroscopic quantum coherence through spontaneous synchronization. The coherence of the excited state decays by superfluorescence, which is redshifted 40 meV from the spontaneous emission with a ∼1700 times faster decay rate and exhibits quadratic fluence dependence. Notably, the excited state population's delayed growth and abrupt decay, which are strongly influenced by the pump fluence and the Burnham-Chiao ringing, are the characteristics of the superfluorescence. Our findings will open up a new frontier for cooperative emission and light beam-based technologies.
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Affiliation(s)
- Ajay K Poonia
- Department of Physics, Indian Institute of Science Education and Research, Bhopal-462066, India
| | - Barnali Mondal
- Department of Chemistry, Indian Institute of Science Education and Research, Pune-411008, India
| | - Matthew C Beard
- Chemistry and Nanoscience Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Angshuman Nag
- Department of Chemistry, Indian Institute of Science Education and Research, Pune-411008, India
| | - K V Adarsh
- Department of Physics, Indian Institute of Science Education and Research, Bhopal-462066, India
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3
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Rose PA, Krich JJ. Interpretations of High-Order Transient Absorption Spectroscopies. J Phys Chem Lett 2023; 14:10849-10855. [PMID: 38032056 DOI: 10.1021/acs.jpclett.3c02491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
Transient absorption (TA) spectroscopy is an invaluable tool for determining the energetics and dynamics of excited states. When pump intensities are sufficiently high, TA spectra include both the generally desired third-order response and responses that are higher in order in the field amplitudes. Recent work demonstrated that pump-intensity-dependent TA measurements allow separating the orders of response, but the information content in those higher orders has not been described. We give a general framework for understanding high-order TA spectra. We extend to higher order the fundamental processes of standard TA: ground-state bleach (GSB), stimulated emission (SE), and excited-state absorption (ESA). Each order introduces two new processes: SE and ESA from previously inaccessible highly excited states and negations of lower-order processes. We show the new spectral and dynamical information at each order and show how the relative signs of the signals in different orders can be used to identify which processes dominate.
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Affiliation(s)
- Peter A Rose
- Department of Physics, University of Ottawa, Ottawa ON K1N 6N5, Canada
| | - Jacob J Krich
- Department of Physics, University of Ottawa, Ottawa ON K1N 6N5, Canada
- Nexus for Quantum Technologies, University of Ottawa, Ottawa ON K1N 6N5, Canada
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4
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Kalka M, Spisak BJ, Woźniak D, Wołoszyn M, Kołaczek D. Dynamical entropic measure of nonclassicality of phase-dependent family of Schrödinger cat states. Sci Rep 2023; 13:16266. [PMID: 37758979 PMCID: PMC10533523 DOI: 10.1038/s41598-023-43421-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 09/23/2023] [Indexed: 09/29/2023] Open
Abstract
The phase-space approach based on the Wigner distribution function is used to study the quantum dynamics of the three families of the Schrödinger cat states identified as the even, odd, and Yurke-Stoler states. The considered states are formed by the superposition of two Gaussian wave packets localized on opposite sides of a smooth barrier in a dispersive medium and moving towards each other. The process generated by this dynamics is analyzed regarding the influence of the barrier parameters on the nonclassical properties of these states in the phase space below and above the barrier regime. The performed analysis employs entropic measure resulting from the Wigner-Rényi entropy for the fixed Rényi index. The universal relation of this entropy for the Rényi index equal one half with the nonclassicality parameter understood as a measure of the negative part of the Wigner distribution function is proved. This relation is confirmed in the series of numerical simulations for the considered states. Furthermore, the obtained results allowed the determination of the lower bound of the Wigner-Rényi entropy for the Rényi index greater than or equal to one half.
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Affiliation(s)
- M Kalka
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059, Krakow, Poland
| | - B J Spisak
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059, Krakow, Poland.
| | - D Woźniak
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059, Krakow, Poland
| | - M Wołoszyn
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059, Krakow, Poland
| | - D Kołaczek
- Department of Applied Mathematics, University of Agriculture in Kraków, ul. Balicka 253c, 30-198, Kraków, Poland
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5
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Wagner K, Iakovlev ZA, Ziegler JD, Cuccu M, Taniguchi T, Watanabe K, Glazov MM, Chernikov A. Diffusion of Excitons in a Two-Dimensional Fermi Sea of Free Charges. NANO LETTERS 2023. [PMID: 37220259 DOI: 10.1021/acs.nanolett.2c03796] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Propagation of light-emitting quasiparticles is of central importance across the fields of condensed matter physics and nanomaterials science. We experimentally demonstrate diffusion of excitons in the presence of a continuously tunable Fermi sea of free charge carriers in a monolayer semiconductor. Light emission from tightly bound exciton states in electrically gated WSe2 monolayer is detected using spatially and temporally resolved microscopy. The measurements reveal a nonmonotonic dependence of the exciton diffusion coefficient on the charge carrier density in both electron and hole doped regimes. Supported by analytical theory describing exciton-carrier interactions in a dissipative system, we identify distinct regimes of elastic scattering and quasiparticle formation determining exciton diffusion. The crossover region exhibits a highly unusual behavior of an increasing diffusion coefficient with increasing carrier densities. Temperature-dependent diffusion measurements further reveal characteristic signatures of freely propagating excitonic complexes dressed by free charges with effective mobilities up to 3 × 103 cm2/(V s).
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Affiliation(s)
- Koloman Wagner
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
- Department of Physics, University of Regensburg, 93053 Regensburg, Germany
| | | | - Jonas D Ziegler
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
- Department of Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Marzia Cuccu
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | | | - Alexey Chernikov
- Institute of Applied Physics and Wüzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
- Department of Physics, University of Regensburg, 93053 Regensburg, Germany
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6
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Barman B, Linn AG, O'Beirne AL, Holleman J, Garcia C, Mapara V, Reno JL, McGill SA, Turkowski V, Karaiskaj D, Hilton DJ. Superradiant emission in a high-mobility two-dimensional electron gas. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35. [PMID: 37075774 DOI: 10.1088/1361-648x/acce8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 04/19/2023] [Indexed: 05/03/2023]
Abstract
We use terahertz time-domain spectroscopy to study gallium arsenide two-dimensional electron gas samples in external magnetic field. We measure cyclotron decay as a function of temperature from 0.4 to10Kand a quantum confinement dependence of the cyclotron decay time belowT0=1.2K. In the wider quantum well, we observe a dramatic enhancement in the decay time due to the reduction in dephasing and the concomitant enhancement of superradiant decay in these systems. We show that the dephasing time in 2DEG's depends on both the scatteringrateand also on the distribution of scattering angles.
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Affiliation(s)
- B Barman
- College of Innovation and Technology, University of Michigan-Flint, Flint, MI 48502, United States of America
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294-1170, United States of America
| | - A G Linn
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294-1170, United States of America
| | - A L O'Beirne
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294-1170, United States of America
| | - J Holleman
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 30201, United States of America
| | - C Garcia
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 30201, United States of America
| | - V Mapara
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - J L Reno
- Center for Integrated Nanotechnologies, Sandia National Laboratory, Albuquerque, NM 87185, United States of America
| | - S A McGill
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 30201, United States of America
| | - V Turkowski
- Department of Physics, University of Central Florida, Orlando, FL 32816, United States of America
| | - D Karaiskaj
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - D J Hilton
- Department of Physics, Baylor University, Waco, TX 76798-7316, United States of America
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7
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Malý P, Lüttig J, Rose PA, Turkin A, Lambert C, Krich JJ, Brixner T. Separating single- from multi-particle dynamics in nonlinear spectroscopy. Nature 2023; 616:280-287. [PMID: 36973449 DOI: 10.1038/s41586-023-05846-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 02/15/2023] [Indexed: 03/29/2023]
Abstract
Quantum states depend on the coordinates of all their constituent particles, with essential multi-particle correlations. Time-resolved laser spectroscopy1 is widely used to probe the energies and dynamics of excited particles and quasiparticles such as electrons and holes2,3, excitons4-6, plasmons7, polaritons8 or phonons9. However, nonlinear signals from single- and multiple-particle excitations are all present simultaneously and cannot be disentangled without a priori knowledge of the system4,10. Here, we show that transient absorption-the most commonly used nonlinear spectroscopy-with N prescribed excitation intensities allows separation of the dynamics into N increasingly nonlinear contributions; in systems well-described by discrete excitations, these N contributions systematically report on zero to N excitations. We obtain clean single-particle dynamics even at high excitation intensities and can systematically increase the number of interacting particles, infer their interaction energies and reconstruct their dynamics, which are not measurable via conventional means. We extract single- and multiple-exciton dynamics in squaraine polymers11,12 and, contrary to common assumption6,13, we find that the excitons, on average, meet several times before annihilating. This surprising ability of excitons to survive encounters is important for efficient organic photovoltaics14,15. As we demonstrate on five diverse systems, our procedure is general, independent of the measured system or type of observed (quasi)particle and straightforward to implement. We envision future applicability in the probing of (quasi)particle interactions in such diverse areas as plasmonics7, Auger recombination2 and exciton correlations in quantum dots5,16,17, singlet fission18, exciton interactions in two-dimensional materials19 and in molecules20,21, carrier multiplication22, multiphonon scattering9 or polariton-polariton interaction8.
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Affiliation(s)
- Pavel Malý
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Würzburg, Germany.
- Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic.
| | - Julian Lüttig
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Würzburg, Germany
| | - Peter A Rose
- Department of Physics, University of Ottawa, Ottawa, Ontario, Canada
| | - Arthur Turkin
- Institut für Organische Chemie, Universität Würzburg, Würzburg, Germany
| | - Christoph Lambert
- Institut für Organische Chemie, Universität Würzburg, Würzburg, Germany
- Center for Nanosystems Chemistry (CNC), Universität Würzburg, Würzburg, Germany
| | - Jacob J Krich
- Department of Physics, University of Ottawa, Ottawa, Ontario, Canada.
- School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, Ontario, Canada.
| | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Würzburg, Germany.
- Center for Nanosystems Chemistry (CNC), Universität Würzburg, Würzburg, Germany.
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8
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Lüders C, Pukrop M, Barkhausen F, Rozas E, Schneider C, Höfling S, Sperling J, Schumacher S, Aßmann M. Tracking Quantum Coherence in Polariton Condensates with Time-Resolved Tomography. PHYSICAL REVIEW LETTERS 2023; 130:113601. [PMID: 37001069 DOI: 10.1103/physrevlett.130.113601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/21/2023] [Indexed: 06/19/2023]
Abstract
Long-term quantum coherence constitutes one of the main challenges when engineering quantum devices. However, easily accessible means to quantify complex decoherence mechanisms are not readily available, nor are sufficiently stable systems. We harness novel phase-space methods-expressed through non-Gaussian convolutions of highly singular Glauber-Sudarshan quasiprobabilities-to dynamically monitor quantum coherence in polariton condensates with significantly enhanced coherence times. Via intensity- and time-resolved reconstructions of such phase-space functions from homodyne detection data, we probe the systems' resourcefulness for quantum information processing up to the nanosecond regime. Our experimental findings are confirmed through numerical simulations, for which we develop an approach that renders established algorithms compatible with our methodology. In contrast to commonly applied phase-space functions, our distributions can be directly sampled from measured data, including uncertainties, and yield a simple operational measure of quantum coherence via the distribution's variance in phase. Therefore, we present a broadly applicable framework and a platform to explore time-dependent quantum phenomena and resources.
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Affiliation(s)
- Carolin Lüders
- Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Matthias Pukrop
- Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn, 33098 Paderborn, Germany
| | - Franziska Barkhausen
- Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn, 33098 Paderborn, Germany
| | - Elena Rozas
- Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | | | - Sven Höfling
- Technische Physik, Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany
| | - Jan Sperling
- Theoretical Quantum Science, Institute for Photonic Quantum Systems (PhoQS), Paderborn University, Warburger Straße 100, 33098 Paderborn, Germany
| | - Stefan Schumacher
- Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn, 33098 Paderborn, Germany
- Wyant College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
| | - Marc Aßmann
- Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany
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9
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Zheng B, Wang J, Wang Q, Su X, Huang T, Li S, Wang F, Shi Y, Wang X. Quantum criticality of excitonic Mott metal-insulator transitions in black phosphorus. Nat Commun 2022; 13:7797. [PMID: 36528720 PMCID: PMC9759515 DOI: 10.1038/s41467-022-35567-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 12/09/2022] [Indexed: 12/23/2022] Open
Abstract
Quantum phase transition refers to the abrupt change of ground states of many-body systems driven by quantum fluctuations. It hosts various intriguing exotic states around its quantum critical points approaching zero temperature. Here we report the spectroscopic and transport evidences of quantum critical phenomena of an exciton Mott metal-insulator-transition in black phosphorus. Continuously tuning the interplay of electron-hole pairs by photo-excitation and using Fourier-transform photo-current spectroscopy as a probe, we measure a comprehensive phase diagram of electron-hole states in temperature and electron-hole pair density parameter space. We characterize an evolution from optical insulator with sharp excitonic transition to metallic electron-hole plasma phases featured by broad absorption and population inversion. We also observe strange metal behavior that resistivity is linear in temperature near the Mott transition boundaries. Our results exemplify an ideal platform to investigating strongly-correlated physics in semiconductors, such as crossover between superconductivity and superfluity of exciton condensation.
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Affiliation(s)
- Binjie Zheng
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
| | - Junzhuan Wang
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
| | - Qianghua Wang
- grid.41156.370000 0001 2314 964XSchool of Physics, Nanjing University, 210093 Nanjing, China
| | - Xin Su
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
| | - Tianye Huang
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
| | - Songlin Li
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
| | - Fengqiu Wang
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
| | - Yi Shi
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
| | - Xiaomu Wang
- grid.41156.370000 0001 2314 964XSchool of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China
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10
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Attosecond clocking of correlations between Bloch electrons. Nature 2022; 610:290-295. [PMID: 36224421 DOI: 10.1038/s41586-022-05190-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 08/03/2022] [Indexed: 11/08/2022]
Abstract
Delocalized Bloch electrons and the low-energy correlations between them determine key optical1, electronic2 and entanglement3 functionalities of solids, all the way through to phase transitions4,5. To directly capture how many-body correlations affect the actual motion of Bloch electrons, subfemtosecond (1 fs = 10-15 s) temporal precision6-15 is desirable. Yet, probing with attosecond (1 as = 10-18 s) high-energy photons has not been energy-selective enough to resolve the relevant millielectronvolt-scale interactions of electrons1-5,16,17 near the Fermi energy. Here, we use multi-terahertz light fields to force electron-hole pairs in crystalline semiconductors onto closed trajectories, and clock the delay between separation and recollision with 300 as precision, corresponding to 0.7% of the driving field's oscillation period. We detect that strong Coulomb correlations emergent in atomically thin WSe2 shift the optimal timing of recollisions by up to 1.2 ± 0.3 fs compared to the bulk material. A quantitative analysis with quantum-dynamic many-body computations in a Wigner-function representation yields a direct and intuitive view on how the Coulomb interaction, non-classical aspects, the strength of the driving field and the valley polarization influence the dynamics. The resulting attosecond chronoscopy of delocalized electrons could revolutionize the understanding of unexpected phase transitions and emergent quantum-dynamic phenomena for future electronic, optoelectronic and quantum-information technologies.
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11
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Tian X, Wei R, Ma Z, Qiu J. Broadband Nonlinear Optical Absorption Induced by Bandgap Renormalization in CVD-Grown Monolayer MoSe 2. ACS APPLIED MATERIALS & INTERFACES 2022; 14:8274-8281. [PMID: 35113533 DOI: 10.1021/acsami.1c23053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Optical modulation on ultrashort time scales is both of central importance and an essential operation for applications in photonics and optoelectronics. Here, with a giant bandgap renormalization due to a high density of carrier injected by a femtosecond pulse, we realize an expected broadband saturable absorption in chemical vapor deposition grown monolayer transition-metal dichalcogenide MoSe2. Our findings reveal the band edge shift from ∼1.53 to ∼0.52 eV under the pump excitation of 0.80 eV, which is induced by the nonequilibrium occupation of electron-hole states after a Mott transition as well as the increase of carrier temperature.
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Affiliation(s)
| | - Rongfei Wei
- Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004, P.R. China
| | - Zhijun Ma
- Zhejiang Laboratory, Hangzhou 311100, P.R. China
| | - Jianrong Qiu
- State Key Laboratory of Modern Optical Instrumentation, College of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, P.R. China
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12
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Liang D, Li H. Optical two-dimensional coherent spectroscopy of many-body dipole-dipole interactions and correlations in atomic vapors. J Chem Phys 2021; 154:214301. [PMID: 34240988 DOI: 10.1063/5.0052982] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Many-body interactions and correlations in atomic ensembles are fundamental in understanding many-body effects such as collective and emergent phenomena and also play an important role in various atom-based applications. Optical two-dimensional coherent spectroscopy (2DCS) provides a powerful tool to measure many-body interactions and correlations. Here, we present the study of many-body dipole-dipole interactions and correlations in potassium and rubidium atomic vapors by using double-quantum and multi-quantum 2DCS. The results show that double-quantum 2DCS provides sensitive and background-free detection of weak dipole-dipole interaction between atoms with a mean separation up to about 16 μm, and multi-quantum 2DCS can excite and detect multi-atom states (Dicke states) with up to eight correlated atoms. The technique of optical 2DCS can provide a new approach to study many-body physics in atomic ensembles and can be potentially implemented to measure many-body effects in cold atoms and other atomic/molecular systems.
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Affiliation(s)
- Danfu Liang
- Department of Physics, Florida International University, Miami, Florida 33199, USA
| | - Hebin Li
- Department of Physics, Florida International University, Miami, Florida 33199, USA
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13
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Zhu WD, Wang R, Wang XY, Xiao M, Zhang CF. Two-dimensional electronic spectroscopy with active phase Management. CHINESE J CHEM PHYS 2021. [DOI: 10.1063/1674-0068/cjcp2012222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Wei-da Zhu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Rui Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xiao-yong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States of America
| | - Chun-feng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
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14
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Borsch M, Schmid CP, Weigl L, Schlauderer S, Hofmann N, Lange C, Steiner JT, Koch SW, Huber R, Kira M. Super-resolution lightwave tomography of electronic bands in quantum materials. Science 2021; 370:1204-1207. [PMID: 33273100 DOI: 10.1126/science.abe2112] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/28/2020] [Indexed: 11/02/2022]
Abstract
Searching for quantum functionalities requires access to the electronic structure, constituting the foundation of exquisite spin-valley-electronic, topological, and many-body effects. All-optical band-structure reconstruction could directly connect electronic structure with the coveted quantum phenomena if strong lightwaves transported localized electrons within preselected bands. Here, we demonstrate that harmonic sideband (HSB) generation in monolayer tungsten diselenide creates distinct electronic interference combs in momentum space. Locating these momentum combs in spectroscopy enables super-resolution tomography of key band-structure details in situ. We experimentally tuned the optical-driver frequency by a full octave and show that the predicted super-resolution manifests in a critical intensity and frequency dependence of HSBs. Our concept offers a practical, all-optical, fully three-dimensional tomography of electronic structure even in microscopically small quantum materials, band by band.
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Affiliation(s)
- M Borsch
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
| | - C P Schmid
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - L Weigl
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - S Schlauderer
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - N Hofmann
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - C Lange
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - J T Steiner
- Department of Physics, University of Marburg, Marburg, Germany
| | - S W Koch
- Department of Physics, University of Marburg, Marburg, Germany
| | - R Huber
- Department of Physics, University of Regensburg, Regensburg, Germany.
| | - M Kira
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA.
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15
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Hu H, Liu XJ. Consistent Theory of Self-Bound Quantum Droplets with Bosonic Pairing. PHYSICAL REVIEW LETTERS 2020; 125:195302. [PMID: 33216582 DOI: 10.1103/physrevlett.125.195302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 10/06/2020] [Indexed: 06/11/2023]
Abstract
We revisit the Bogoliubov theory of quantum droplets proposed by Petrov [Phys. Rev. Lett. 115, 155302 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.155302] for an ultracold Bose-Bose mixture, where the mean-field collapse is stabilized by the Lee-Huang-Yang quantum fluctuations. We show that a loophole in Petrov's theory, i.e., the ignorance of the softening complex Bogoliubov spectrum, can be naturally removed by the introduction of bosonic pairing. The pairing leads to weaker mean-field attractions, and also a stronger Lee-Huang-Yang term in the case of unequal intraspecies interactions. As a result, the equilibrium density for the formation of self-bound droplets significantly decreases in the deep droplet regime, in agreement with a recent observation from diffusion Monte Carlo simulations. Our construction of a consistent Bogoliubov theory paves the way to understand the puzzling low critical number of small quantum droplets observed in the experiment [C. Cabrera et al., Science 359, 301 (2018)SCIEAS0036-807510.1126/science.aao5686].
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Affiliation(s)
- Hui Hu
- Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne, Victoria 3122, Australia
| | - Xia-Ji Liu
- Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne, Victoria 3122, Australia
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16
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Baldini E, Palmieri T, Dominguez A, Rubio A, Chergui M. Giant Exciton Mott Density in Anatase TiO_{2}. PHYSICAL REVIEW LETTERS 2020; 125:116403. [PMID: 32976006 DOI: 10.1103/physrevlett.125.116403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 07/04/2020] [Accepted: 08/17/2020] [Indexed: 06/11/2023]
Abstract
Elucidating the carrier density at which strongly bound excitons dissociate into a plasma of uncorrelated electron-hole pairs is a central topic in the many-body physics of semiconductors. However, there is a lack of information on the high-density response of excitons absorbing in the near-to-mid ultraviolet, due to the absence of suitable experimental probes in this elusive spectral range. Here, we present a unique combination of many-body perturbation theory and state-of-the-art ultrafast broadband ultraviolet spectroscopy to unveil the interplay between the ultraviolet-absorbing two-dimensional excitons of anatase TiO_{2} and a sea of electron-hole pairs. We discover that the critical density for the exciton Mott transition in this material is the highest ever reported in semiconductors. These results deepen our knowledge of the exciton Mott transition and pave the route toward the investigation of the exciton phase diagram in a variety of wide-gap insulators.
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Affiliation(s)
- Edoardo Baldini
- Laboratory of Ultrafast Spectroscopy, ISIC and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Department of Physics, Massachusetts Institute of Technology, 02139 Cambridge, Massachusetts, USA
| | - Tania Palmieri
- Laboratory of Ultrafast Spectroscopy, ISIC and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Adriel Dominguez
- Bremen Center for Computational Material Science (BCCMS), Bremen 28359, Germany
- Shenzhen JL Computational Science and Applied Research Institute (CSAR), Shenzhen 518110, China
- Beijing Computational Research Center (CSRC), Beijing 100193, China
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
- Departamento Física de Materiales, Universidad del País Vasco, Avenida Tolosa 72, E-20018 San Sebastian, Spain
- Center for Computational Quantum Physics, The Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
| | - Majed Chergui
- Laboratory of Ultrafast Spectroscopy, ISIC and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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17
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Wang Z, Sun H, Zhang Q, Feng J, Zhang J, Li Y, Ning CZ. Excitonic complexes and optical gain in two-dimensional molybdenum ditelluride well below the Mott transition. LIGHT, SCIENCE & APPLICATIONS 2020; 9:39. [PMID: 32194953 PMCID: PMC7064520 DOI: 10.1038/s41377-020-0278-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/21/2020] [Accepted: 02/27/2020] [Indexed: 05/06/2023]
Abstract
Semiconductors that can provide optical gain at extremely low carrier density levels are critically important for applications such as energy efficient nanolasers. However, all current semiconductor lasers are based on traditional semiconductor materials that require extremely high density levels above the so-called Mott transition to realize optical gain. The new emerging 2D materials provide unprecedented opportunities for studying new excitonic physics and exploring new optical gain mechanisms at much lower density levels due to the strong Coulomb interaction and co-existence and mutual conversion of excitonic complexes. Here, we report a new gain mechanism involving charged excitons or trions in electrically gated 2D molybdenum ditelluride well below the Mott density. Our combined experimental and modelling study not only reveals the complex interplay of excitonic complexes well below the Mott transition but also establishes 2D materials as a new class of gain materials at densities 4-5 orders of magnitude lower than those of conventional semiconductors and provides a foundation for lasing at ultralow injection levels for future energy efficient photonic devices. Additionally, our study could help reconcile recent conflicting results on 2D materials: While 2D material-based lasers have been demonstrated at extremely low densities with spectral features dominated by various excitonic complexes, optical gain was only observed in experiments at densities several orders of magnitude higher, beyond the Mott density. We believe that our results could lead to more systematic studies on the relationship between the mutual conversion of excitonic species and the existence of optical gain well below the Mott transition.
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Affiliation(s)
- Zhen Wang
- Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China
- Frontier Science Center for Quantum Information, 100084 Beijing, China
- Beijing National Research Center for Information Science and Technology, 100084 Beijing, China
| | - Hao Sun
- Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China
- Frontier Science Center for Quantum Information, 100084 Beijing, China
- Beijing National Research Center for Information Science and Technology, 100084 Beijing, China
| | - Qiyao Zhang
- Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China
- Frontier Science Center for Quantum Information, 100084 Beijing, China
- Beijing National Research Center for Information Science and Technology, 100084 Beijing, China
| | - Jiabin Feng
- Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China
- Frontier Science Center for Quantum Information, 100084 Beijing, China
- Beijing National Research Center for Information Science and Technology, 100084 Beijing, China
| | - Jianxing Zhang
- Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China
- Frontier Science Center for Quantum Information, 100084 Beijing, China
- Beijing National Research Center for Information Science and Technology, 100084 Beijing, China
| | - Yongzhuo Li
- Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China
- Frontier Science Center for Quantum Information, 100084 Beijing, China
- Beijing National Research Center for Information Science and Technology, 100084 Beijing, China
| | - Cun-Zheng Ning
- Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China
- Frontier Science Center for Quantum Information, 100084 Beijing, China
- Beijing National Research Center for Information Science and Technology, 100084 Beijing, China
- School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, AZ 85287 USA
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18
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Palmieri T, Baldini E, Steinhoff A, Akrap A, Kollár M, Horváth E, Forró L, Jahnke F, Chergui M. Mahan excitons in room-temperature methylammonium lead bromide perovskites. Nat Commun 2020; 11:850. [PMID: 32051405 PMCID: PMC7016123 DOI: 10.1038/s41467-020-14683-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 01/21/2020] [Indexed: 11/09/2022] Open
Abstract
In a seminal paper, Mahan predicted that excitonic bound states can still exist in a semiconductor at electron-hole densities above the insulator-to-metal Mott transition. However, no clear evidence for this exotic quasiparticle, dubbed Mahan exciton, exists to date at room temperature. In this work, we combine ultrafast broadband optical spectroscopy and advanced many-body calculations to reveal that organic-inorganic lead-bromide perovskites host Mahan excitons at room temperature. Persistence of the Wannier exciton peak and the enhancement of the above-bandgap absorption are observed at all achievable photoexcitation densities, well above the Mott density. This is supported by the solution of the semiconductor Bloch equations, which confirms that no sharp transition between the insulating and conductive phase occurs. Our results demonstrate the robustness of the bound states in a regime where exciton dissociation is otherwise expected, and offer promising perspectives in fundamental physics and in room-temperature applications involving high densities of charge carriers.
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Affiliation(s)
- Tania Palmieri
- Laboratory of Ultrafast Spectroscopy, Lausanne Centre for Ultrafast Science (LACUS), Institute of Chemistry and Chemical Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Edoardo Baldini
- Laboratory of Ultrafast Spectroscopy, Lausanne Centre for Ultrafast Science (LACUS), Institute of Chemistry and Chemical Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
| | - Alexander Steinhoff
- Semiconductor Theory Group, Institute for Theoretical Physics, University of Bremen, Otto-Hahn-Alle 1, P.O. Box 330440, Bremen, Germany
| | - Ana Akrap
- Group of Light Fermion Spectroscopy, Department of Physics, Université de Fribourg, 3 Chemin du Musée, 1700, Fribourg, Switzerland
| | - Márton Kollár
- Laboratory of Physics of Condensed Matter, Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Endre Horváth
- Laboratory of Physics of Condensed Matter, Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - László Forró
- Laboratory of Physics of Condensed Matter, Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Frank Jahnke
- Semiconductor Theory Group, Institute for Theoretical Physics, University of Bremen, Otto-Hahn-Alle 1, P.O. Box 330440, Bremen, Germany
| | - Majed Chergui
- Laboratory of Ultrafast Spectroscopy, Lausanne Centre for Ultrafast Science (LACUS), Institute of Chemistry and Chemical Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
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19
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Wei R, Tian X, Yang L, Yang D, Ma Z, Guo H, Qiu J. Ultrafast and large optical nonlinearity of a TiSe 2 saturable absorber in the 2 μm wavelength region. NANOSCALE 2019; 11:22277-22285. [PMID: 31570910 DOI: 10.1039/c9nr06374a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The non-equilibrium state of correlated electron materials is crucial for both scientific research and practical applications in optoelectronic and photonic devices. Because of the weak optical nonlinearity of most materials even under a dense optical excitation, it is desirable to achieve a significant nonlinear optical response with ultrafast and large optical nonlinearity utilizing a common material. Here, an ultrafast response and large optical nonlinearity induced by non-equilibrium electrons in typical transition metal dichalcogenides, TiSe2, are investigated in the 1.55-2.0 μm wavelength region. Significantly, we observe an ultrafast transient dynamics of 491 femtoseconds as well as a large optical nonlinearity with a saturable coefficient of -0.17 cm GW-1 (1.55 μm) and -0.10 cm GW-1 (2.0 μm). Upon increasing pump fluence, TiSe2 exhibits an enhanced bleaching response amplitude up to 563%. Furthermore, a stable Q-switched fiber laser in the 2.0 μm wavelength region is achieved by employing the TiSe2-saturable absorber. The findings offer the potential design to enhance the optical nonlinearity via non-equilibrium electrons for advanced photonic devices.
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Affiliation(s)
- Rongfei Wei
- Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.
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20
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Yu Y, Bataller AW, Younts R, Yu Y, Li G, Puretzky AA, Geohegan DB, Gundogdu K, Cao L. Room-Temperature Electron-Hole Liquid in Monolayer MoS 2. ACS NANO 2019; 13:10351-10358. [PMID: 31483608 DOI: 10.1021/acsnano.9b04124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Excitons in semiconductors are usually noninteracting and behave like an ideal gas, but may condense to a strongly correlated liquid-like state, i.e., electron-hole liquid (EHL), at high density and appropriate temperature. An EHL is a macroscopic quantum state with exotic properties and represents the ultimate attainable charge excitation density in steady states. It bears great promise for a variety of fields such as ultra-high-power photonics and quantum science and technology. However, the condensation of gas-like excitons to an EHL has often been restricted to cryogenic temperatures, which significantly limits the prospect of EHLs for use in practical applications. Herein we demonstrate the formation of an EHL at room temperature in monolayer MoS2 by taking advantage of the monolayer's extraordinarily strong exciton binding energy. This work demonstrates the potential for the liquid-like state of charge excitations to be a useful platform for the studies of macroscopic quantum phenomena and the development of optoelectronic devices.
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Affiliation(s)
- Yiling Yu
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Alexander W Bataller
- Department of Physics , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Robert Younts
- Department of Physics , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Yifei Yu
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Guoqing Li
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Alexander A Puretzky
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - David B Geohegan
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Kenan Gundogdu
- Department of Physics , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Linyou Cao
- Department of Materials Science and Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
- Department of Physics , North Carolina State University , Raleigh , North Carolina 27695 , United States
- Department of Electrical and Computer Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States
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21
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Wang CY, Elliott P, Sharma S, Dewhurst JK. Real time scissor correction in TD-DFT. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:214002. [PMID: 30721894 DOI: 10.1088/1361-648x/ab048a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We demonstrate how the scissor correction to the optical band gap, common in linear-response time-dependent density functional theory (TD-DFT), may be extended to the domain of real-time TD-DFT. This requires modifying both the eigenvalues and momentum matrix elements of the underlying basis set. It provides a simple and computationally economical approach for calculating accurate electron dynamics in solids. We demonstrate the importance of this correction for prototypical semiconductors, diamond and silicon, where the energy absorption in both the linear and non-linear regimes is examined. We also show that for a particular system, ZnSe, using the adiabatic local density approximation together with a scissor correction can be advantageous over other approximations, as the underlying quasi-particle band structure is more accurate.
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Affiliation(s)
- C-Y Wang
- Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany
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22
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Kulig M, Zipfel J, Nagler P, Blanter S, Schüller C, Korn T, Paradiso N, Glazov MM, Chernikov A. Exciton Diffusion and Halo Effects in Monolayer Semiconductors. PHYSICAL REVIEW LETTERS 2018; 120:207401. [PMID: 29864294 DOI: 10.1103/physrevlett.120.207401] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/12/2018] [Indexed: 05/28/2023]
Abstract
We directly monitor exciton propagation in freestanding and SiO_{2}-supported WS_{2} monolayers through spatially and time-resolved microphotoluminescence under ambient conditions. We find a highly nonlinear behavior with characteristic, qualitative changes in the spatial profiles of the exciton emission and an effective diffusion coefficient increasing from 0.3 to more than 30 cm^{2}/s, depending on the injected exciton density. Solving the diffusion equation while accounting for Auger recombination allows us to identify and quantitatively understand the main origin of the increase in the observed diffusion coefficient. At elevated excitation densities, the initial Gaussian distribution of the excitons evolves into long-lived halo shapes with μm-scale diameter, indicating additional memory effects in the exciton dynamics.
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Affiliation(s)
- Marvin Kulig
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Jonas Zipfel
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Philipp Nagler
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Sofia Blanter
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Christian Schüller
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Tobias Korn
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Nicola Paradiso
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | | | - Alexey Chernikov
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
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23
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Steinleitner P, Merkl P, Graf A, Nagler P, Watanabe K, Taniguchi T, Zipfel J, Schüller C, Korn T, Chernikov A, Brem S, Selig M, Berghäuser G, Malic E, Huber R. Dielectric Engineering of Electronic Correlations in a van der Waals Heterostructure. NANO LETTERS 2018; 18:1402-1409. [PMID: 29365262 DOI: 10.1021/acs.nanolett.7b05132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Heterostructures of van der Waals bonded layered materials offer unique means to tailor dielectric screening with atomic-layer precision, opening a fertile field of fundamental research. The optical analyses used so far have relied on interband spectroscopy. Here we demonstrate how a capping layer of hexagonal boron nitride (hBN) renormalizes the internal structure of excitons in a WSe2 monolayer using intraband transitions. Ultrabroadband terahertz probes sensitively map out the full complex-valued mid-infrared conductivity of the heterostructure after optical injection of 1s A excitons. This approach allows us to trace the energies and line widths of the atom-like 1s-2p transition of optically bright and dark excitons as well as the densities of these quasiparticles. The excitonic resonance red shifts and narrows in the WSe2/hBN heterostructure compared to the bare monolayer. Furthermore, the ultrafast temporal evolution of the mid-infrared response function evidences the formation of optically dark excitons from an initial bright population. Our results provide key insight into the effect of nonlocal screening on electron-hole correlations and open new possibilities of dielectric engineering of van der Waals heterostructures.
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Affiliation(s)
- Philipp Steinleitner
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Philipp Merkl
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Alexander Graf
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Philipp Nagler
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Kenji Watanabe
- National Institute for Material Science , 305-0044 1-1 Namiki Tsukuba, Ibaraki, Japan
| | - Takashi Taniguchi
- National Institute for Material Science , 305-0044 1-1 Namiki Tsukuba, Ibaraki, Japan
| | - Jonas Zipfel
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Christian Schüller
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Tobias Korn
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Alexey Chernikov
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
| | - Samuel Brem
- Department of Physics, Chalmers University of Technology , Fysikgården 1, 41258 Gothenburg, Sweden
| | - Malte Selig
- Department of Theoretical Physics, Technical University of Berlin , Hardenbergstraße 36, 10623 Berlin, Germany
| | - Gunnar Berghäuser
- Department of Physics, Chalmers University of Technology , Fysikgården 1, 41258 Gothenburg, Sweden
| | - Ermin Malic
- Department of Physics, Chalmers University of Technology , Fysikgården 1, 41258 Gothenburg, Sweden
| | - Rupert Huber
- Department of Physics, University of Regensburg , Universitätsstraße 31, 93053 Regensburg, Germany
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24
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Zhu W, Wang R, Zhang C, Wang G, Liu Y, Zhao W, Dai X, Wang X, Cerullo G, Cundiff S, Xiao M. Broadband two-dimensional electronic spectroscopy in an actively phase stabilized pump-probe configuration. OPTICS EXPRESS 2017; 25:21115-21126. [PMID: 29041519 DOI: 10.1364/oe.25.021115] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 08/15/2017] [Indexed: 05/27/2023]
Abstract
We introduce a novel configuration for two-dimensional electronic spectroscopy (2DES) that combines the partially collinear pump-probe geometry with active phase locking. We demonstrate the method on a solution sample of CdSe/ZnS nanocrystals by employing two non-collinear optical parametric amplifiers as the pump and probe sources. The two collinear pump pulse replicas are created using a Mach-Zehnder interferometer phase stabilized by active feedback electronics. Taking the advantage of separated paths of the two pump pulses in the interferometer, we improve the signal-to-noise ratio with double modulation of the individual pump beams. In addition, a quartz wedge pair manipulates the phase difference between the two pump pulses, enabling the recovery of the rephasing and non-rephasing signals. Our setup integrates many advantages of available 2DES techniques with robust phase stabilization, ultrafast time resolution, two-color operation, long delay scan, individual polarization manipulation and the ease of implementation.
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25
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Langer F, Hohenleutner M, Schmid CP, Poellmann C, Nagler P, Korn T, Schüller C, Sherwin MS, Huttner U, Steiner JT, Koch SW, Kira M, Huber R. Lightwave-driven quasiparticle collisions on a subcycle timescale. Nature 2016; 533:225-9. [PMID: 27172045 PMCID: PMC5034899 DOI: 10.1038/nature17958] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 03/18/2016] [Indexed: 12/24/2022]
Abstract
Ever since Ernest Rutherford scattered α-particles from gold foils, collision experiments have revealed insights into atoms, nuclei and elementary particles. In solids, many-body correlations lead to characteristic resonances--called quasiparticles--such as excitons, dropletons, polarons and Cooper pairs. The structure and dynamics of quasiparticles are important because they define macroscopic phenomena such as Mott insulating states, spontaneous spin- and charge-order, and high-temperature superconductivity. However, the extremely short lifetimes of these entities make practical implementations of a suitable collider challenging. Here we exploit lightwave-driven charge transport, the foundation of attosecond science, to explore ultrafast quasiparticle collisions directly in the time domain: a femtosecond optical pulse creates excitonic electron-hole pairs in the layered dichalcogenide tungsten diselenide while a strong terahertz field accelerates and collides the electrons with the holes. The underlying dynamics of the wave packets, including collision, pair annihilation, quantum interference and dephasing, are detected as light emission in high-order spectral sidebands of the optical excitation. A full quantum theory explains our observations microscopically. This approach enables collision experiments with various complex quasiparticles and suggests a promising new way of generating sub-femtosecond pulses.
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Affiliation(s)
- F Langer
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - M Hohenleutner
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - C P Schmid
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - C Poellmann
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - P Nagler
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - T Korn
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - C Schüller
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - M S Sherwin
- Department of Physics and the Institute for Terahertz Science and Technology, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - U Huttner
- Department of Physics, University of Marburg, 35032 Marburg, Germany
| | - J T Steiner
- Department of Physics, University of Marburg, 35032 Marburg, Germany
| | - S W Koch
- Department of Physics, University of Marburg, 35032 Marburg, Germany
| | - M Kira
- Department of Physics, University of Marburg, 35032 Marburg, Germany
| | - R Huber
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
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26
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Appavoo K, Liu X, Menon V, Sfeir MY. Excitonic Lasing in Solution-Processed Subwavelength Nanosphere Assemblies. NANO LETTERS 2016; 16:2004-10. [PMID: 26840127 DOI: 10.1021/acs.nanolett.5b05274] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Lasing in solution-processed nanomaterials has gained significant interest because of the potential for low-cost integrated photonic devices. Still, a key challenge is to utilize a comprehensive knowledge of the system's spectral and temporal dynamics to design low-threshold lasing devices. Here, we demonstrate intrinsic lasing (without external cavity) at low-threshold in an ultrathin film of coupled, highly crystalline nanospheres with overall thickness on the order of ∼λ/4. The cavity-free geometry consists of ∼35 nm zinc oxide nanospheres that collectively localize the in-plane emissive light fields while minimizing scattering losses, resulting in excitonic lasing with fluence thresholds at least an order of magnitude lower than previous UV-blue random and quantum-dot lasers (<75 μJ/cm(2)). Fluence-dependent effects, as quantified by subpicosecond transient spectroscopy, highlight the role of phonon-mediated processes in excitonic lasing. Subpicosecond evolution of distinct lasing modes, together with three-dimensional electromagnetic simulations, indicate a random lasing process, which is in violation of the commonly cited criteria of strong scattering from individual nanostructures and an optically thick sample. Subsequently, an electron-hole plasma mechanism is observed with increased fluence. These results suggest that coupled nanostructures with high crystallinity, fabricated by low-cost solution-processing methods, can function as viable building blocks for high-performance optoelectronics devices.
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Affiliation(s)
- Kannatassen Appavoo
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Xiaoze Liu
- Department of Physics, City College of New York , New York, New York 10031, United States
| | - Vinod Menon
- Department of Physics, City College of New York , New York, New York 10031, United States
| | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
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27
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López Carreño JC, Sánchez Muñoz C, Sanvitto D, del Valle E, Laussy FP. Exciting Polaritons with Quantum Light. PHYSICAL REVIEW LETTERS 2015; 115:196402. [PMID: 26588401 DOI: 10.1103/physrevlett.115.196402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Indexed: 06/05/2023]
Abstract
We discuss the excitation of polaritons-strongly coupled states of light and matter-by quantum light, instead of the usual laser or thermal excitation. As one illustration of the new horizons thus opened, we introduce "Mollow spectroscopy"-a theoretical concept for a spectroscopic technique that consists of scanning the output of resonance fluorescence onto an optical target-from which weak nonlinearities can be read with high precision even in strongly dissipative environments.
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Affiliation(s)
- J C López Carreño
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - C Sánchez Muñoz
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - D Sanvitto
- CNR NANOTEC-Institute of Nanotechnology, Via Monteroni, 73100 Lecce, Italy
| | - E del Valle
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - F P Laussy
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Russian Quantum Center, Novaya 100, 143025 Skolkovo, Moscow Region, Russia
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28
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Spieker M, Pascu S, Zilges A, Iachello F. Origin of low-lying enhanced E1 strength in rare-Earth nuclei. PHYSICAL REVIEW LETTERS 2015; 114:192504. [PMID: 26024168 DOI: 10.1103/physrevlett.114.192504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Indexed: 06/04/2023]
Abstract
The experimental E1 strength distribution below 4 MeV in rare-earth nuclei suggests a local breaking of isospin symmetry. In addition to the octupole states, additional J^{π}=1^{-} states with enhanced E1 strength have been observed in rare-earth nuclei by means of (γ,γ') experiments. By reproducing the experimental results, the spdf interacting boson model calculations provide further evidence for the formation of an α cluster in medium-mass nuclei and might provide a new understanding of the origin of low-lying E1 strength.
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Affiliation(s)
- M Spieker
- Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
| | - S Pascu
- Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
- National Institute for Physics and Nuclear Engineering, R-77125 Bucharest-Magurele, Romania
| | - A Zilges
- Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
| | - F Iachello
- Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520-8120, USA
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29
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Kira M. Coherent quantum depletion of an interacting atom condensate. Nat Commun 2015; 6:6624. [PMID: 25767044 PMCID: PMC4382704 DOI: 10.1038/ncomms7624] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 02/12/2015] [Indexed: 12/02/2022] Open
Abstract
Sufficiently strong interactions promote coherent quantum transitions in spite of thermalization and losses, which are the adversaries of delicate effects such as reversibility and correlations. In atomic Bose–Einstein condensates (BECs), strong atom–atom interactions can eject atoms from the BEC to the normal component, yielding quantum depletion instead of temperature depletion. A recent experiment has already been verified to overcome losses. Here I show that it also achieves coherent quantum-depletion dynamics in a BEC swept fast enough from weak to strong atom–atom interactions. The elementary coherent process first excites the normal component into a liquid state that evolves into a spherical shell state, where the atom occupation peaks at a finite momentum to shield 50% of the BEC atoms from annihilation. The identified coherent processes resemble ultrafast semiconductor excitations expanding the scope of BEC explorations to many-body non-equilibrium studies. To overcome losses and thermalization, a quantum system requires strong interactions. Following recent experiments, Mackillo Kira shows that a BEC swept fast enough from weak to strong interactions exhibits coherent quantum-depletion dynamics dominated by particle clusters, resembling semiconductor excitations.
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Affiliation(s)
- M Kira
- Department of Physics, Philipps-University Marburg, Renthof 5, D-35032 Marburg, Germany
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30
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Baker LR, Jiang CM, Kelly ST, Lucas JM, Vura-Weis J, Gilles MK, Alivisatos AP, Leone SR. Charge carrier dynamics of photoexcited Co3O4 in methanol: extending high harmonic transient absorption spectroscopy to liquid environments. NANO LETTERS 2014; 14:5883-90. [PMID: 25222441 DOI: 10.1021/nl502817a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Charge carrier dynamics in Co3O4 thin films are observed using high harmonic generation transient absorption spectroscopy at the Co M2,3 edge. Results reveal that photoexcited Co3O4 decays to the ground state in 600 ± 40 ps in liquid methanol compared to 1.9 ± 0.3 ns in vacuum. Kinetic analysis suggests that surface-mediated relaxation of photoexcited Co3O4 may be the result of hole transfer from Co3O4 followed by carrier recombination at the Co3O4-methanol interface.
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Affiliation(s)
- L Robert Baker
- Department of Chemistry, ‡Department of Mechanical Engineering, and §Department of Physics, University of California , Berkeley, Berkeley, California 94720, United States
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31
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Berger C, Huttner U, Mootz M, Kira M, Koch SW, Tempel JS, Aßmann M, Bayer M, Mintairov AM, Merz JL. Quantum-memory effects in the emission of quantum-dot microcavities. PHYSICAL REVIEW LETTERS 2014; 113:093902. [PMID: 25215985 DOI: 10.1103/physrevlett.113.093902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Indexed: 06/03/2023]
Abstract
The experimentally measured input-output characteristics of optically pumped semiconductor microcavities exhibits unexpected oscillations modifying the fundamentally linear slope in the excitation power regime below lasing. A systematic microscopic analysis reproduces these oscillations, identifying them as a genuine quantum-memory effect, i.e., a photon-density correlation accumulated during the excitation. With the use of projected quantum measurements, it is shown that the input-output oscillations can be controlled and enhanced by an order of magnitude when the quantum fluctuations of the pump are adjusted.
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Affiliation(s)
- C Berger
- Department of Physics, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany
| | - U Huttner
- Department of Physics, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany
| | - M Mootz
- Department of Physics, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany
| | - M Kira
- Department of Physics, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany
| | - S W Koch
- Department of Physics, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany
| | - J-S Tempel
- Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - M Aßmann
- Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - M Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany and Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Saint Petersburg, 194021, Russia
| | - A M Mintairov
- Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Saint Petersburg, 194021, Russia and Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - J L Merz
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
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32
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Chemitrends. INDIAN CHEMICAL ENGINEER 2014. [DOI: 10.1080/00194506.2014.918327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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