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Resolving the gravitational redshift across a millimetre-scale atomic sample. Nature 2022; 602:420-424. [PMID: 35173346 DOI: 10.1038/s41586-021-04349-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/13/2021] [Indexed: 11/09/2022]
Abstract
Einstein's theory of general relativity states that clocks at different gravitational potentials tick at different rates relative to lab coordinates-an effect known as the gravitational redshift1. As fundamental probes of space and time, atomic clocks have long served to test this prediction at distance scales from 30 centimetres to thousands of kilometres2-4. Ultimately, clocks will enable the study of the union of general relativity and quantum mechanics once they become sensitive to the finite wavefunction of quantum objects oscillating in curved space-time. Towards this regime, we measure a linear frequency gradient consistent with the gravitational redshift within a single millimetre-scale sample of ultracold strontium. Our result is enabled by improving the fractional frequency measurement uncertainty by more than a factor of 10, now reaching 7.6 × 10-21. This heralds a new regime of clock operation necessitating intra-sample corrections for gravitational perturbations.
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2
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Mizoguchi M, Zhang Y, Kunimi M, Tanaka A, Takeda S, Takei N, Bharti V, Koyasu K, Kishimoto T, Jaksch D, Glaetzle A, Kiffner M, Masella G, Pupillo G, Weidemüller M, Ohmori K. Ultrafast Creation of Overlapping Rydberg Electrons in an Atomic BEC and Mott-Insulator Lattice. PHYSICAL REVIEW LETTERS 2020; 124:253201. [PMID: 32639753 DOI: 10.1103/physrevlett.124.253201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
We study an array of ultracold atoms in an optical lattice (Mott insulator) excited with a coherent ultrashort laser pulse to a state where single-electron wave functions spatially overlap. Beyond a threshold principal quantum number where Rydberg orbitals of neighboring lattice sites overlap with each other, the atoms efficiently undergo spontaneous Penning ionization resulting in a drastic change of ion-counting statistics, sharp increase of avalanche ionization, and the formation of an ultracold plasma. These observations signal the actual creation of electronic states with overlapping wave functions, which is further confirmed by a significant difference in ionization dynamics between a Bose-Einstein condensate and a Mott insulator. This system is a promising platform for simulating electronic many-body phenomena dominated by Coulomb interactions in the condensed phase.
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Affiliation(s)
- M Mizoguchi
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Y Zhang
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, and Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - M Kunimi
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - A Tanaka
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - S Takeda
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - N Takei
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - V Bharti
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - K Koyasu
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - T Kishimoto
- Department of Engineering Science and Institute for Advanced Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - D Jaksch
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
- Center for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
| | - A Glaetzle
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
- Center for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
| | - M Kiffner
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
- Center for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
| | - G Masella
- icFRC and ISIS (UMR 7006), Université de Strasbourg and CNRS, 67000 Strasbourg, France
| | - G Pupillo
- icFRC and ISIS (UMR 7006), Université de Strasbourg and CNRS, 67000 Strasbourg, France
| | - M Weidemüller
- Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - K Ohmori
- Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Aichi 444-8585, Japan
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3
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Zych M, Costa F, Pikovski I, Brukner Č. Bell's theorem for temporal order. Nat Commun 2019; 10:3772. [PMID: 31434883 PMCID: PMC6704104 DOI: 10.1038/s41467-019-11579-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 07/17/2019] [Indexed: 11/09/2022] Open
Abstract
Time has a fundamentally different character in quantum mechanics and in general relativity. In quantum theory events unfold in a fixed order while in general relativity temporal order is influenced by the distribution of matter. When matter requires a quantum description, temporal order is expected to become non-classical-a scenario beyond the scope of current theories. Here we provide a direct description of such a scenario. We consider a thought experiment with a massive body in a spatial superposition and show how it leads to entanglement of temporal orders between time-like events. This entanglement enables accomplishing a task, violation of a Bell inequality, that is impossible under local classical temporal order; it means that temporal order cannot be described by any pre-defined local variables. A classical notion of a causal structure is therefore untenable in any framework compatible with the basic principles of quantum mechanics and classical general relativity.
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Affiliation(s)
- Magdalena Zych
- Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St. Lucia, QLD, 4072, Australia.
| | - Fabio Costa
- Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Igor Pikovski
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138, USA.,Department of Physics, Harvard University, Cambridge, MA, 02138, USA.,Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Časlav Brukner
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna, Austria.,Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090, Vienna, Austria
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4
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Yang Y, Chiribella G, Hayashi M. Quantum stopwatch: how to store time in a quantum memory. Proc Math Phys Eng Sci 2018; 474:20170773. [PMID: 29887749 DOI: 10.1098/rspa.2017.0773] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Accepted: 04/24/2018] [Indexed: 11/12/2022] Open
Abstract
Quantum mechanics imposes a fundamental trade-off between the accuracy of time measurements and the size of the systems used as clocks. When the measurements of different time intervals are combined, the errors due to the finite clock size accumulate, resulting in an overall inaccuracy that grows with the complexity of the set-up. Here, we introduce a method that, in principle, eludes the accumulation of errors by coherently transferring information from a quantum clock to a quantum memory of the smallest possible size. Our method could be used to measure the total duration of a sequence of events with enhanced accuracy, and to reduce the amount of quantum communication needed to stabilize clocks in a quantum network.
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Affiliation(s)
- Yuxiang Yang
- Department of Computer Science, The University of Hong Kong, Pokfulam Road, Hong Kong.,HKU Shenzhen Institute of Research and Innovation Yuexing 2nd Rd Nanshan, Shenzhen 518057, People's Republic of China
| | - Giulio Chiribella
- Department of Computer Science, The University of Oxford, Parks Road, Oxford, UK.,Canadian Institute for Advanced Research, CIFAR Program in Quantum Information Science, Toronto, ON, Canada M5G 1Z8
| | - Masahito Hayashi
- Graduate School of Mathematics, Nagoya University, Nagoya, Japan.,Centre for Quantum Technologies, National University of Singapore, Singapore
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5
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Eldredge Z, Foss-Feig M, Gross JA, Rolston SL, Gorshkov AV. Optimal and secure measurement protocols for quantum sensor networks. PHYSICAL REVIEW. A 2018; 97:10.1103/PhysRevA.97.042337. [PMID: 31093589 PMCID: PMC6513338 DOI: 10.1103/physreva.97.042337] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Studies of quantum metrology have shown that the use of many-body entangled states can lead to an enhancement in sensitivity when compared with unentangled states. In this paper, we quantify the metrological advantage of entanglement in a setting where the measured quantity is a linear function of parameters individually coupled to each qubit. We first generalize the Heisenberg limit to the measurement of nonlocal observables in a quantum network, deriving a bound based on the multiparameter quantum Fisher information. We then propose measurement protocols that can make use of Greenberger-Horne-Zeilinger (GHZ) states or spin-squeezed states and show that in the case of GHZ states the protocol is optimal, i.e., it saturates our bound. We also identify nanoscale magnetic resonance imaging as a promising setting for this technology.
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Affiliation(s)
- Zachary Eldredge
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742, USA
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742, USA
| | - Michael Foss-Feig
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742, USA
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742, USA
- United States Army Research Laboratory, Adelphi, Maryland 20783, USA
| | - Jonathan A Gross
- Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - S L Rolston
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742, USA
| | - Alexey V Gorshkov
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742, USA
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742, USA
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6
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Li L, Kuzmich A. Quantum memory with strong and controllable Rydberg-level interactions. Nat Commun 2016; 7:13618. [PMID: 27869195 PMCID: PMC5121357 DOI: 10.1038/ncomms13618] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 10/19/2016] [Indexed: 11/29/2022] Open
Abstract
Realization of distributed quantum systems requires fast generation and long-term storage of quantum states. Ground atomic states enable memories with storage times in the range of a minute, however their relatively weak interactions do not allow fast creation of non-classical collective states. Rydberg atomic systems feature fast preparation of singly excited collective states and their efficient mapping into light, but storage times in these approaches have not yet exceeded a few microseconds. Here we demonstrate a system that combines fast quantum state generation and long-term storage. An initially prepared coherent state of an atomic memory is transformed into a non-classical collective atomic state by Rydberg-level interactions in less than a microsecond. By sheltering the quantum state in the ground atomic levels, the storage time is increased by almost two orders of magnitude. This advance opens a door to a number of quantum protocols for scalable generation and distribution of entanglement. Quantum information processing requires long-storage time of quantum states, but this typically comes at the expense of their addressability. Here the authors developed a method that exploits interaction between Rydberg and ground states of an atom reporting fast state generation and long-term storage.
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Affiliation(s)
- Lin Li
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - A Kuzmich
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
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7
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Endres M, Bernien H, Keesling A, Levine H, Anschuetz ER, Krajenbrink A, Senko C, Vuletic V, Greiner M, Lukin MD. Atom-by-atom assembly of defect-free one-dimensional cold atom arrays. Science 2016; 354:1024-1027. [PMID: 27811284 DOI: 10.1126/science.aah3752] [Citation(s) in RCA: 179] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/17/2016] [Indexed: 11/02/2022]
Abstract
The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a platform for the deterministic preparation of regular one-dimensional arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of more than 50 atoms in less than 400 milliseconds. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach may enable controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.
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Affiliation(s)
- Manuel Endres
- Department of Physics, Harvard University, Cambridge, MA 02138, USA. .,Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
| | - Hannes Bernien
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | | | - Harry Levine
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Eric R Anschuetz
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | | | - Crystal Senko
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Vladan Vuletic
- Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Markus Greiner
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Mikhail D Lukin
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
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