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Millington-Hotze P, Dyte HE, Manna S, Covre da Silva SF, Rastelli A, Chekhovich EA. Approaching a fully-polarized state of nuclear spins in a solid. Nat Commun 2024; 15:985. [PMID: 38307879 PMCID: PMC10837425 DOI: 10.1038/s41467-024-45364-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 01/18/2024] [Indexed: 02/04/2024] Open
Abstract
Magnetic noise of atomic nuclear spins is a major source of decoherence in solid-state spin qubits. In theory, near-unity nuclear spin polarization can eliminate decoherence of the electron spin qubit, while turning the nuclei into a useful quantum information resource. However, achieving sufficiently high nuclear polarizations has remained an evasive goal. Here we implement a nuclear spin polarization protocol which combines strong optical pumping and fast electron tunneling. Nuclear polarizations well above 95% are generated in GaAs semiconductor quantum dots on a timescale of 1 minute. The technique is compatible with standard quantum dot device designs, where highly-polarized nuclear spins can simplify implementations of qubits and quantum memories, as well as offer a testbed for studies of many-body quantum dynamics and magnetism.
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Affiliation(s)
- Peter Millington-Hotze
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, United Kingdom
| | - Harry E Dyte
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, United Kingdom
| | - Santanu Manna
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Str. 69, Linz, 4040, Austria
- Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Saimon F Covre da Silva
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Str. 69, Linz, 4040, Austria
| | - Armando Rastelli
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Str. 69, Linz, 4040, Austria
| | - Evgeny A Chekhovich
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, United Kingdom.
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2
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Saleem Y, Sadecka K, Korkusinski M, Miravet D, Dusko A, Hawrylak P. Theory of Excitons in Gated Bilayer Graphene Quantum Dots. Nano Lett 2023; 23:2998-3004. [PMID: 36962005 DOI: 10.1021/acs.nanolett.3c00406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We present a theory of excitons in gated bilayer graphene (BLG) quantum dots (QDs). Electrical gating of BLG opens an energy gap, turning this material into an electrically tunable semiconductor. Unlike in laterally gated semiconductor QDs, where electrons are attracted and holes repelled, we show here that lateral structuring of metallic gates results in a gated lateral QD confining both electrons and holes. Using an accurate atomistic approach and exact diagonalization tools, we describe strongly interacting electrons and holes forming an electrically tunable exciton. We find these excitons to be different from those found in semiconductor QDs and nanocrystals, with exciton energy tunable by voltage from the terahertz to far infrared (FIR) range. The conservation of spin, valley, and orbital angular momentum results in an exciton fine structure with a band of dark low-energy states, making this system a promising candidate for storage, detection and emission of photons in the terahertz range.
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Affiliation(s)
- Yasser Saleem
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
| | - Katarzyna Sadecka
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
- Institute of Theoretical Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Marek Korkusinski
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
- Security and Disruptive Technologies, National Research Council, Ottawa K1A0R6, Canada
| | - Daniel Miravet
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
| | - Amintor Dusko
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
| | - Pawel Hawrylak
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
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3
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Ge Z, Slizovskiy S, Polizogopoulos P, Joshi T, Taniguchi T, Watanabe K, Lederman D, Fal'ko VI, Velasco J. Giant orbital magnetic moments and paramagnetic shift in artificial relativistic atoms and molecules. Nat Nanotechnol 2023; 18:250-256. [PMID: 36879123 DOI: 10.1038/s41565-023-01327-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
Materials such as graphene and topological insulators host massless Dirac fermions that enable the study of relativistic quantum phenomena. Single quantum dots and coupled quantum dots formed with massless Dirac fermions can be viewed as artificial relativistic atoms and molecules, respectively. Such structures offer a unique testbed to study atomic and molecular physics in the ultrarelativistic regime (particle speed close to the speed of light). Here we use a scanning tunnelling microscope to create and probe single and coupled electrostatically defined graphene quantum dots to unravel the magnetic-field responses of artificial relativistic nanostructures. We observe a giant orbital Zeeman splitting and orbital magnetic moment up to ~70 meV T-1 and ~600μB (μB, Bohr magneton) in single graphene quantum dots. For coupled graphene quantum dots, Aharonov-Bohm oscillations and a strong Van Vleck paramagnetic shift of ~20 meV T-2 are observed. Our findings provide fundamental insights into relativistic quantum dot states, which can be potentially leveraged for use in quantum information science.
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Affiliation(s)
- Zhehao Ge
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Sergey Slizovskiy
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Booth Street East, Manchester, UK
| | | | - Toyanath Joshi
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics and National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - David Lederman
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Vladimir I Fal'ko
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
- National Graphene Institute, University of Manchester, Booth Street East, Manchester, UK.
- Henry Royce Institute for Advanced Materials, Manchester, UK.
| | - Jairo Velasco
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA, USA.
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4
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Polatkan S, Goerbig MO, Wyzula J, Kemmler R, Maulana LZ, Piot BA, Crassee I, Akrap A, Shekhar C, Felser C, Dressel M, Pronin AV, Orlita M. Magneto-Optics of a Weyl Semimetal beyond the Conical Band Approximation: Case Study of TaP. Phys Rev Lett 2020; 124:176402. [PMID: 32412257 DOI: 10.1103/physrevlett.124.176402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
Landau-level spectroscopy, the optical analysis of electrons in materials subject to a strong magnetic field, is a versatile probe of the electronic band structure and has been successfully used in the identification of novel states of matter such as Dirac electrons, topological materials or Weyl semimetals. The latter arise from a complex interplay between crystal symmetry, spin-orbit interaction, and inverse ordering of electronic bands. Here, we report on unusual Landau-level transitions in the monopnictide TaP that decrease in energy with increasing magnetic field. We show that these transitions arise naturally at intermediate energies in time-reversal-invariant Weyl semimetals where the Weyl nodes are formed by a partially gapped nodal-loop in the band structure. We propose a simple theoretical model for electronic bands in these Weyl materials that captures the collected magneto-optical data to great extent.
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Affiliation(s)
- S Polatkan
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - M O Goerbig
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS UMR 8502, 91405 Orsay Cedex, France
| | - J Wyzula
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25 rue des Martyrs, 38042 Grenoble, France
| | - R Kemmler
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - L Z Maulana
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - B A Piot
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25 rue des Martyrs, 38042 Grenoble, France
| | - I Crassee
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25 rue des Martyrs, 38042 Grenoble, France
| | - A Akrap
- Department of Physics, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - C Shekhar
- Max Planck Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - C Felser
- Max Planck Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - M Dressel
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - A V Pronin
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - M Orlita
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25 rue des Martyrs, 38042 Grenoble, France
- Charles University, Faculty of Mathematics and Physics, Institute of Physics, Ke Karlovu 5, 121 16 Prague 2, Czech Republic
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5
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Jaworowski B, Rogers N, Grabowski M, Hawrylak P. Macroscopic Singlet-Triplet Qubit in Synthetic Spin-One Chain in Semiconductor Nanowires. Sci Rep 2017; 7:5529. [PMID: 28717208 DOI: 10.1038/s41598-017-05655-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/01/2017] [Indexed: 11/18/2022] Open
Abstract
We show here how to create macroscopic quantum states in a semiconductor device: a chain of InAs quantum dots embedded in an InP nanowire. Filling the nanowire with 4 electrons per dot creates a synthetic spin-one chain, with four-fold degenerate topological ground state protected by a Haldane gap. The four states correspond to two spin-½ quasiparticles localised at the ends of the macroscopic wire. The quasiparticle spins are mapped onto a robust, macroscopic, singlet-triplet qubit. These predictions are supported by a microscopic theory and extensive numerical simulations.
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6
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Abstract
An energy shell structure depending on eccentricity is analyzed in a dielectric elliptic microcavity. Through the analysis, it is explicated that the energy shell structure is governed by classical constant actions of periodic orbits. For clarification, the relation between dominances of the periodic orbits and bifurcation behaviors are obtained and the length spectra based on eigenvalues computed by a numerical method are compared with the exact lengths of the periodic orbits obtained by analytic calculations. By matching effective wave numbers obtained from the periodic orbit lengths to exact wave numbers of stationary states in closed and open cavities, we find deviations provoked from the openness. We show that these deviations are caused by additional phase factors in the Einstein-Brillouin-Keller quantization.
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Affiliation(s)
- Chang-Hwan Yi
- Department of Emerging Materials Science, DGIST, Hyeonpung-myeon, Dalseong-gun, Daegu 711-873, Korea
| | - Hyeon-Hye Yu
- Department of Physics, Sogang University, Seoul 121-742, Korea
| | - Ji-Won Lee
- Department of Emerging Materials Science, DGIST, Hyeonpung-myeon, Dalseong-gun, Daegu 711-873, Korea
| | - Ji-Hwan Kim
- Department of Emerging Materials Science, DGIST, Hyeonpung-myeon, Dalseong-gun, Daegu 711-873, Korea
| | - Chil-Min Kim
- Department of Emerging Materials Science, DGIST, Hyeonpung-myeon, Dalseong-gun, Daegu 711-873, Korea
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7
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Ravi Kishore VV, Partoens B, Peeters FM. Electronic and optical properties of core-shell nanowires in a magnetic field. J Phys Condens Matter 2014; 26:095501. [PMID: 24521608 DOI: 10.1088/0953-8984/26/9/095501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The electronic and optical properties of zincblende nanowires are investigated in the presence of a uniform magnetic field directed along the [001] growth direction within the k · p method. We focus our numerical study on core-shell nanowires consisting of the III-V materials GaAs, Al(x)Ga(1-x)As and (Al(y)Ga(1-y))₀.₅₁In₀.₄₉P. Nanowires with electrons confined in the core exhibit a Fock-Darwin-like spectrum, whereas nanowires with electrons confined in the shell show Aharonov-Bohm oscillations. Thus, by properly choosing the core and the shell materials of the nanowire, the optical properties in a magnetic field can be tuned in very different ways.
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Affiliation(s)
- V V Ravi Kishore
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Department of Condensed Matter Physics and Material Sciences, S N Bose National Centre for Basic Sciences, Sector-III, Block-JD, Salt Lake, Kolkata-700 098, India
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8
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Zieliński M. Valence band offset, strain and shape effects on confined states in self-assembled InAs/InP and InAs/GaAs quantum dots. J Phys Condens Matter 2013; 25:465301. [PMID: 24129261 DOI: 10.1088/0953-8984/25/46/465301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
I present a systematic study of self-assembled InAs/InP and InAs/GaAs quantum dot single-particle and many-body properties as a function of the quantum dot-surrounding matrix valence band offset. I use an atomistic, empirical tight-binding approach and perform numerically demanding calculations for half-million-atom nanosystems. I demonstrate that the overall confinement in quantum dots is a non-trivial interplay of two key factors: strain effects and the valence band offset. I show that strain effects determine both the peculiar structure of confined hole states of lens type InAs/GaAs quantum dots and the characteristic 'shell-like' structure of confined hole states in the commonly considered 'low-strain' lens type InAs/InP quantum dot. I also demonstrate that strain leads to single-band-like behavior of hole states of disk type ('indium flushed') InAs/GaAs and InAs/InP quantum dots. I show how strain and valence band offset affect quantum dot many-body properties: the excitonic fine structure, an important factor for efficient entangled photon pair generation, and the biexciton and charged exciton binding energies.
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Affiliation(s)
- M Zieliński
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun, Poland
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9
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Abolfath RM, Korkusinski M, Brabec T, Hawrylak P. Spin textures in strongly coupled electron spin and magnetic or nuclear spin systems in quantum dots. Phys Rev Lett 2012; 108:247203. [PMID: 23004315 DOI: 10.1103/physrevlett.108.247203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/20/2012] [Indexed: 06/01/2023]
Abstract
Controlling electron spins strongly coupled to magnetic and nuclear spins in solid state systems is an important challenge in the field of spintronics and quantum computation. We show here that electron droplets with no net spin in semiconductor quantum dots strongly coupled with magnetic ion or nuclear spin systems break down at low temperature and form a nontrivial antiferromagnetic spatially ordered spin texture of magnetopolarons. The spatially ordered combined electron-magnetic ion spin texture, associated with spontaneous symmetry breaking in the parity of electronic charge and spin densities and magnetization of magnetic ions, emerges from an ab initio density functional approach to the electronic system coupled with mean-field approximation for the magnetic or nuclear spin system. The predicted phase diagram determines the critical temperature as a function of coupling strength and identifies possible phases of the strongly coupled spin system. The prediction may arrest fluctuations in the spin system and open the way to control, manipulate, and prepare magnetic and nuclear spin ensembles in semiconductor nanostructures.
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Affiliation(s)
- Ramin M Abolfath
- School of Natural Sciences and Mathematics, University of Texas at Dallas, Richardson, Texas 75080, USA
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10
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Affiliation(s)
- Manus Hayne
- Department of Physics; Lancaster University; Lancaster; LA1 4YB; United Kingdom
| | - Bhavtosh Bansal
- Indian Institute of Science Education & Research - Kolkata; Monhanpur Campus; Nadia; 741252; West Bengal; India
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11
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Trojnar AH, Korkusiński M, Kadantsev ES, Hawrylak P, Goryca M, Kazimierczuk T, Kossacki P, Wojnar P, Potemski M. Quantum interference in exciton-Mn spin interactions in a CdTe semiconductor quantum dot. Phys Rev Lett 2011; 107:207403. [PMID: 22181774 DOI: 10.1103/physrevlett.107.207403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Indexed: 05/31/2023]
Abstract
We show theoretically and experimentally the existence of a new quantum-interference effect between the electron-hole interactions and the scattering by a single Mn impurity. The theoretical model, including electron-valence-hole correlations, the short- and long-range exchange interaction of a Mn ion with the heavy hole and with electron and anisotropy of the quantum dot, is compared with photoluminescence spectroscopy of CdTe dots with single magnetic ions. We show how the design of the electronic levels of a quantum dot enables the design of an exciton, control of the quantum interference, and hence engineering of light-Mn interaction.
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Affiliation(s)
- A H Trojnar
- Institute for Microstructural Sciences, National Research Council, Ottawa, Canada
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12
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13
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Bennett SD, Cockins L, Miyahara Y, Grütter P, Clerk AA. Strong electromechanical coupling of an atomic force microscope cantilever to a quantum dot. Phys Rev Lett 2010; 104:017203. [PMID: 20366389 DOI: 10.1103/physrevlett.104.017203] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Indexed: 05/29/2023]
Abstract
We present theoretical and experimental results on the mechanical damping of an atomic force microscope cantilever strongly coupled to a self-assembled InAs quantum dot. When the cantilever oscillation amplitude is large, its motion dominates the charge dynamics of the dot which in turn leads to nonlinear, amplitude-dependent damping of the cantilever. We observe highly asymmetric line shapes of Coulomb blockade peaks in the damping that reflect the degeneracy of energy levels on the dot. Furthermore, we predict that excited state spectroscopy is possible by studying the damping versus oscillation amplitude, in analogy with varying the amplitude of an ac gate voltage.
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Affiliation(s)
- Steven D Bennett
- Department of Physics, McGill University, Montreal, Quebec, Canada H3A 2T8
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14
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Kioseoglou G, Yasar M, Li CH, Korkusinski M, Diaz-Avila M, Hanbicki AT, Hawrylak P, Petrou A, Jonker BT. Intershell exchange and sequential electrically injected spin populations of InAs quantum-dot shell states. Phys Rev Lett 2008; 101:227203. [PMID: 19113518 DOI: 10.1103/physrevlett.101.227203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Indexed: 05/27/2023]
Abstract
We report sequential spin population of individual shell states of self-assembled InAs quantum dots controlled by a spin-polarized current from an Fe contact, and determine the s-p and p-d intershell exchange energies. We resolve excitonic features in the electroluminescence (EL) spectra associated with individual quantum levels. In contrast with simple models of shell occupation, the EL circular polarization exhibits maxima shifted with respect to the intensity peaks. Calculations show that this is due to intershell exchange. Exchange energies for the s-p and p-d shells are 7+/-2 and 13.5+/-1 meV, respectively.
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Affiliation(s)
- G Kioseoglou
- Naval Research Laboratory, Washington, District of Columbia 20375,
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15
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Korkusinski M, Hawrylak P. Optical signatures of spin polarization of carriers in quantum dots. Phys Rev Lett 2008; 101:027205. [PMID: 18764224 DOI: 10.1103/physrevlett.101.027205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Indexed: 05/26/2023]
Abstract
We predict theoretically the optical signatures of spin polarization of carriers in self-assembled quantum dots. The emission spectra are mapped out as a function of increasing electron spin polarization for a fixed number of electrons and holes. The spin-polarized spectra are determined using exact diagonalization techniques for up to 12 particles, corresponding to two lowest filled shells. We predict that the spin polarization leads to photon polarization, to redshifts of emission lines due to excess exchange interactions among the spin-polarized electrons, and to a complete breakup of emission lines for spin-polarized electronic shells.
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Affiliation(s)
- Marek Korkusinski
- Quantum Theory Group, Institute for Microstructural Sciences, National Research Council, Ottawa, K1A0R6, Canada
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16
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Gaudreau L, Studenikin SA, Sachrajda AS, Zawadzki P, Kam A, Lapointe J, Korkusinski M, Hawrylak P. Stability diagram of a few-electron triple dot. Phys Rev Lett 2006; 97:036807. [PMID: 16907532 DOI: 10.1103/physrevlett.97.036807] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Indexed: 05/11/2023]
Abstract
Individual and coupled quantum dots containing one or two electrons have been realized and are regarded as components for future quantum information circuits. In this Letter we map out experimentally the stability diagram of the few-electron triple dot system, the electron configuration map as a function of the external tuning parameters, and reveal experimentally for the first time the existence of quadruple points, a signature of the three dots being in resonance. In the vicinity of these quadruple points we observe a duplication of charge transfer transitions related to charge and spin reconfigurations triggered by changes in the total electron occupation number. The experimental results are largely reproduced by equivalent circuit analysis and Hubbard models. Our results are relevant for future quantum mechanical engineering applications within both quantum information and quantum cellular automata architectures.
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Affiliation(s)
- L Gaudreau
- Institute For Microstructural Sciences, NRC, Ottawa, Canada K1 A 0R6
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17
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Abstract
We present a theory of interaction of magnetic Mn ions depending strongly on the number (Ne) of electrons in a quantum dot. For closed electronic shells, we derive the RKKY interaction and its dependence on magnetic ion positions, quantum dot energy quantization omega0, and the number of filled shells Ns. For partially filled shells, the many-electron magnetopolaron effect leads to effective carrier mediated ferromagnetic Mn-Mn interactions. The dependence of the magnetopolaron energy on magnetic ion positions, quantum dot energy quantization omega0, and the number of electrons Ne is predicted.
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Affiliation(s)
- Fanyao Qu
- Institute for Microstructural Sciences, National Research Council of Canada, Ottawa, K1A 0R6, Canada
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18
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Qu F, Hawrylak P. Magnetic exchange interactions in quantum dots containing electrons and magnetic ions. Phys Rev Lett 2005; 95:217206. [PMID: 16384179 DOI: 10.1103/physrevlett.95.217206] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Indexed: 05/05/2023]
Abstract
We present a theory of magnetic exchange interactions in quantum dots containing electrons and magnetic ions. We find the interaction between the electron and Mn ion to depend strongly on the number of electrons. It can be switched off for closed shell configurations and maximized for partially filled shells. However, unlike the total electron spin S which is maximized for half-filled shells, we predict the exchange interaction to be independent of the filling of the electronic shell. We show how this unusual effect manifests itself in quantum dot addition and excitation spectrum.
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Affiliation(s)
- Fanyao Qu
- Institute for Microstructural Sciences, National Research Council of Canada, Ottawa, K1A 0R6, Canada
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