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Bounds CC, Duff JP, Tritt A, Taylor HAM, Coe GX, White SJ, Turner LD. Quantum Spectral Analysis by Continuous Measurement of Landau-Zener Transitions. PHYSICAL REVIEW LETTERS 2024; 132:093401. [PMID: 38489644 DOI: 10.1103/physrevlett.132.093401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 01/17/2024] [Indexed: 03/17/2024]
Abstract
We demonstrate the simultaneous estimation of signal frequency and amplitude by a single quantum sensor in a single experimental shot. Sweeping the qubit splitting linearly across a span of frequencies induces a nonadiabatic Landau-Zener transition as the qubit crosses resonance. The signal frequency determines the time of the transition, and the amplitude its extent. Continuous weak measurement of this unitary evolution informs a parameter estimator retrieving precision measurements of frequency and amplitude. Implemented on radio-frequency-dressed ultracold atoms read out by a Faraday spin-light interface, we sense a magnetic signal with estimated sensitivities to amplitude of 11 pT/sqrt[Hz], frequency 0.026 Hz/Hz^{3/2}, and phase 0.084 rad/sqrt[Hz], in a single 300 ms sweep from 7 to 13 kHz. The protocol realizes a swept-sine quantum spectrum analyzer, potentially sensing hundreds or thousands of channels with a single quantum sensor.
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Affiliation(s)
- Christopher C Bounds
- School of Physics and Astronomy, Monash University, Melbourne, Victoria 3800, Australia
| | - Josh P Duff
- School of Physics and Astronomy, Monash University, Melbourne, Victoria 3800, Australia
| | - Alex Tritt
- School of Physics and Astronomy, Monash University, Melbourne, Victoria 3800, Australia
| | - Hamish A M Taylor
- School of Physics and Astronomy, Monash University, Melbourne, Victoria 3800, Australia
| | - George X Coe
- School of Physics and Astronomy, Monash University, Melbourne, Victoria 3800, Australia
| | - Sam J White
- School of Physics and Astronomy, Monash University, Melbourne, Victoria 3800, Australia
| | - L D Turner
- School of Physics and Astronomy, Monash University, Melbourne, Victoria 3800, Australia
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2
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Chomaz L, Ferrier-Barbut I, Ferlaino F, Laburthe-Tolra B, Lev BL, Pfau T. Dipolar physics: a review of experiments with magnetic quantum gases. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 86:026401. [PMID: 36583342 DOI: 10.1088/1361-6633/aca814] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Since the achievement of quantum degeneracy in gases of chromium atoms in 2004, the experimental investigation of ultracold gases made of highly magnetic atoms has blossomed. The field has yielded the observation of many unprecedented phenomena, in particular those in which long-range and anisotropic dipole-dipole interactions (DDIs) play a crucial role. In this review, we aim to present the aspects of the magnetic quantum-gas platform that make it unique for exploring ultracold and quantum physics as well as to give a thorough overview of experimental achievements. Highly magnetic atoms distinguish themselves by the fact that their electronic ground-state configuration possesses a large electronic total angular momentum. This results in a large magnetic moment and a rich electronic transition spectrum. Such transitions are useful for cooling, trapping, and manipulating these atoms. The complex atomic structure and large dipolar moments of these atoms also lead to a dense spectrum of resonances in their two-body scattering behaviour. These resonances can be used to control the interatomic interactions and, in particular, the relative importance of contact over dipolar interactions. These features provide exquisite control knobs for exploring the few- and many-body physics of dipolar quantum gases. The study of dipolar effects in magnetic quantum gases has covered various few-body phenomena that are based on elastic and inelastic anisotropic scattering. Various many-body effects have also been demonstrated. These affect both the shape, stability, dynamics, and excitations of fully polarised repulsive Bose or Fermi gases. Beyond the mean-field instability, strong dipolar interactions competing with slightly weaker contact interactions between magnetic bosons yield new quantum-stabilised states, among which are self-bound droplets, droplet assemblies, and supersolids. Dipolar interactions also deeply affect the physics of atomic gases with an internal degree of freedom as these interactions intrinsically couple spin and atomic motion. Finally, long-range dipolar interactions can stabilise strongly correlated excited states of 1D gases and also impact the physics of lattice-confined systems, both at the spin-polarised level (Hubbard models with off-site interactions) and at the spinful level (XYZ models). In the present manuscript, we aim to provide an extensive overview of the various related experimental achievements up to the present.
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Affiliation(s)
- Lauriane Chomaz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - Igor Ferrier-Barbut
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127 Palaiseau, France
| | - Francesca Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - Bruno Laburthe-Tolra
- Université Sorbonne Paris Nord, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France
- CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - Benjamin L Lev
- Departments of Physics and Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA 94305, United States of America
| | - Tilman Pfau
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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Feldmann P, Klempt C, Smerzi A, Santos L, Gessner M. Interferometric Order Parameter for Excited-State Quantum Phase Transitions in Bose-Einstein Condensates. PHYSICAL REVIEW LETTERS 2021; 126:230602. [PMID: 34170156 DOI: 10.1103/physrevlett.126.230602] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 03/05/2021] [Accepted: 04/19/2021] [Indexed: 06/13/2023]
Abstract
Excited-state quantum phase transitions extend the notion of quantum phase transitions beyond the ground state. They are characterized by closing energy gaps amid the spectrum. Identifying order parameters for excited-state quantum phase transitions poses, however, a major challenge. We introduce a topological order parameter that distinguishes excited-state phases in a large class of mean-field models and can be accessed by interferometry in current experiments with spinor Bose-Einstein condensates. Our work opens a way for the experimental characterization of excited-state quantum phases in atomic many-body systems.
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Affiliation(s)
- Polina Feldmann
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany
| | - Carsten Klempt
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Institut für Satellitengeodäsie und Inertialsensorik, c/o Leibniz Universität Hannover, DLR-SI, Callinstraße 36, 30167 Hannover, Germany
| | - Augusto Smerzi
- QSTAR, INO-CNR, and LENS, Largo Enrico Fermi 2, 50125 Firenze, Italy
| | - Luis Santos
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany
| | - Manuel Gessner
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 24 Rue Lhomond, 75005 Paris, France
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Lao D, Raman C, de Melo CARS. Nematic-Orbit Coupling and Nematic Density Waves in Spin-1 Condensates. PHYSICAL REVIEW LETTERS 2020; 124:173203. [PMID: 32412270 DOI: 10.1103/physrevlett.124.173203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 03/18/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
We propose the creation of artificial nematic-orbit coupling in spin-1 Bose-Einstein condensates, in analogy with spin-orbit coupling. Using a suitably designed microwave chip, the quadratic Zeeman shift, normally uniform in space, can be made to be spatiotemporally varying, leading to a coupling between spatial and nematic degrees of freedom. A phase diagram is explored where three quantum phases with the nematic order emerge: easy axis, easy plane with single-well structure, and easy plane with double-well structure in momentum space. By including spin-dependent and spin-independent interactions, we also obtain the low energy excitation spectra in these three phases. Last, we show that the nematic-orbit coupling leads to a periodic nematic density modulation in relation to the period λ_{T} of the cosinusoidal quadratic Zeeman term. Our results point to the rich possibilities for manipulation of tensorial degrees of freedom in ultracold gases without requiring Raman lasers, and therefore, obviating light-scattering induced heating.
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Affiliation(s)
- Di Lao
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Chandra Raman
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - C A R Sá de Melo
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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Xu P, Yi S, Zhang W. Efficient Generation of Many-Body Entangled States by Multilevel Oscillations. PHYSICAL REVIEW LETTERS 2019; 123:073001. [PMID: 31491105 DOI: 10.1103/physrevlett.123.073001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Indexed: 06/10/2023]
Abstract
We generate high-fidelity massively entangled states in an antiferromagnetic spin-1 Bose-Einstein condensate (BEC) by utilizing multilevel oscillations. Combining the multilevel oscillations with additional adiabatic drives, we greatly shorten the necessary evolution time and relax the requirement on the control accuracy of quadratic Zeeman splitting, from microgauss to milligauss, for a ^{23}Na spinor BEC. The achieved high fidelities over 96% show that two kinds of massively entangled states, the many-body singlet state and the twin-Fock state, are almost perfectly generated. The generalized spin squeezing parameter drops to a value far below the standard quantum limit even with the presence of atom number fluctuations and stray magnetic fields, illustrating the robustness of our protocol under real experimental conditions. The generated many-body entangled states can be employed to achieve the Heisenberg-limit quantum precision measurement and to attack nonclassical problems in quantum information science.
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Affiliation(s)
- Peng Xu
- School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, China
| | - Su Yi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190, China
- School of Physical Sciences & CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenxian Zhang
- School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, China
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Hurst HM, Spielman IB. Measurement-induced dynamics and stabilization of spinor-condensate domain walls. PHYSICAL REVIEW. A 2019; 99:10.1103/physreva.99.053612. [PMID: 32166204 PMCID: PMC7067049 DOI: 10.1103/physreva.99.053612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Weakly measuring many-body systems and allowing for feedback in real time can simultaneously create and measure new phenomena in quantum systems. We theoretically study the dynamics of a continuously measured two-component Bose-Einstein condensate (BEC) potentially containing a domain wall and focus on the tradeoff between usable information obtained from measurement and quantum backaction. Each weakly measured system yields a measurement record from which we extract real-time dynamics of the domain wall. We show that quantum backaction due to measurement causes two primary effects: domain-wall diffusion and overall heating. The system dynamics and signal-to-noise ratio depend on the choice of measurement observable. We propose a feedback protocol to dynamically create a stable domain wall in the regime where domain walls are unstable, giving a prototype example of Hamiltonian engineering using measurement and feedback.
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Affiliation(s)
- Hilary M Hurst
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, Maryland 20899, USA
| | - I B Spielman
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, Maryland 20899, USA
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Zan X, Liu J, Han J, Wu J, Li Y. Phase diagrams and multistep condensations of spin-1 bosonic gases in optical lattices. Sci Rep 2018; 8:9143. [PMID: 29904172 PMCID: PMC6002366 DOI: 10.1038/s41598-018-27503-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 06/04/2018] [Indexed: 12/03/2022] Open
Abstract
Motivated by recent experimental processes, we systemically investigate strongly correlated spin-1 ultracold bosons trapped in a three-dimensional optical lattice in the presence of an external magnetic field. Based on a recently developed bosonic dynamical mean-field theory (BDMFT), we map out complete phase diagrams of the system for both antiferromagnetic and ferromagnetic interactions, where various phases are found as a result of the interplay of spin-dependent interaction and quadratic Zeeman energy. For antiferromagnetic interactions, the system demonstrates competing magnetic orders, including nematic, spin-singlet and ferromagnetic insulating phase, depending on longitudinal magnetization, whereas, for ferromagnetic case, a ferromagnetic-to-nematic-insulating phase transition is observed for small quadratic Zeeman energy, and the insulating phase demonstrates the nematic order for large Zeeman energy. Interestingly, at low magnetic field and finite temperature, we find an abnormal multi-step condensation of the strongly correlated superfluid, i.e. the critical condensing temperature of the mF = −1 component with antiferromagnetic interactions demonstrates an increase with longitudinal magnetization, while, for ferromagnetic case, the Zeeman component mF = 0 demonstrates a local minimum for the critical condensing temperature, in contrast to weakly interacting cases.
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Affiliation(s)
- Xiaolei Zan
- Department of Physics, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Jing Liu
- Department of Physics, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Jinsen Han
- Department of Physics, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Jianhua Wu
- Department of Physics, National University of Defense Technology, Changsha, 410073, P. R. China.
| | - Yongqiang Li
- Department of Physics, National University of Defense Technology, Changsha, 410073, P. R. China.
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8
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Masson SJ, Barrett MD, Parkins S. Cavity QED Engineering of Spin Dynamics and Squeezing in a Spinor Gas. PHYSICAL REVIEW LETTERS 2017; 119:213601. [PMID: 29219405 DOI: 10.1103/physrevlett.119.213601] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Indexed: 06/07/2023]
Abstract
We propose a method for engineering spin dynamics in ensembles of integer-spin atoms confined within a high-finesse optical cavity. Our proposal uses cavity-assisted Raman transitions to engineer a Dicke model for integer-spin atoms, which, in a dispersive limit, reduces to effective atom-atom interactions within the ensemble. This scheme offers a promising and flexible new avenue for the exploration of a wide range of spinor many-body physics. As an example of this, we present results showing that this method can be used to generate spin-nematic squeezing in an ensemble of spin-1 atoms. With realistic parameters, the scheme should enable substantial squeezing on time scales much shorter than current experiments with spin-1 Bose-Einstein condensates.
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Affiliation(s)
- Stuart J Masson
- Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - M D Barrett
- Centre for Quantum Technologies, 3 Science Drive 2, Singapore 117543
- Department of Physics, National University of Singapore, 3 Science Drive 2, Singapore 117543
| | - Scott Parkins
- Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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9
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Mathew R, Tiesinga E. Phase-space mixing in dynamically unstable, integrable few-mode quantum systems. PHYSICAL REVIEW. A 2017; 96:013604. [PMID: 29876535 PMCID: PMC5986195 DOI: 10.1103/physreva.96.013604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Quenches in isolated quantum systems are currently a subject of intense study. Here, we consider quantum few-mode systems that are integrable in their classical mean-field limit and become dynamically unstable after a quench of a system parameter. Specifically, we study a Bose-Einstein condensate (BEC) in a double-well potential and an antiferromagnetic spinor BEC constrained to a single spatial mode. We study the time dynamics after the quench within the truncated Wigner approximation (TWA), focus on the role of motion near separatrices, and find that system relaxes to a steady state due to phase-space mixing. Using the action-angle formalism and a pendulum as an illustration, we derive general analytical expressions for the time evolution of expectation values of observables and their long-time limits. We find that the deviation of the long-time expectation value from its classical value scales as O(1/ln N), where N is the number of atoms in the condensate. Furthermore, the relaxation of an observable to its steady-state value is a damped oscillation. The damping is Gaussian in time with a time scale of O[(ln N)2]. We also give the quantitative dependence of the steady-state value and the damping time on the system parameters. Our results are confirmed with numerical TWA simulations.
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Affiliation(s)
- R Mathew
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - E Tiesinga
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland 20899, USA
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10
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Phase diagram and spin mixing dynamics in spinor condensates with a microwave dressing field. Sci Rep 2015; 5:14464. [PMID: 26403676 PMCID: PMC4585920 DOI: 10.1038/srep14464] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/21/2015] [Indexed: 11/10/2022] Open
Abstract
Spinor condensates immersed in a microwave dressing field, which access both negative and positive values of the net quadratic Zeeman effect, have been realized in a recent experiment. In this report, we study the ground state properties of a spinor condensate with a microwave dressing field which enables us to access both negative and positive values of quadratic Zeeman energy. The ground state exhibits three different phases by varying the magnetization and the net quadratic Zeeman energy for both cases of ferromagnetic and antiferromagnetic interactions. We investigate the atomic-number fluctuations of the ground state and show that the hyperfine state displays super-Poissonian and sub-Poissonian distributions in the different phases. We also discuss the dynamical properties and show that the separatrix has a remarkable relation to the magnetization.
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11
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Marti GE, MacRae A, Olf R, Lourette S, Fang F, Stamper-Kurn DM. Coherent magnon optics in a ferromagnetic spinor Bose-Einstein condensate. PHYSICAL REVIEW LETTERS 2014; 113:155302. [PMID: 25375719 DOI: 10.1103/physrevlett.113.155302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Indexed: 06/04/2023]
Abstract
We measure the dispersion relation, gap, and magnetic moment of a magnon in the ferromagnetic F = 1 spinor Bose-Einstein condensate of (87)Rb. From the dispersion relation we measure an average effective mass 1.033(2)(stat)(10)(sys) times the atomic mass, as determined by interfering standing and running coherent magnon waves within the dense and trapped condensed gas. The measured mass is higher than theoretical predictions of mean-field and beyond-mean-field Beliaev theory for a bulk spinor Bose gas with s-wave contact interactions. We observe a magnon energy gap of h × 2.5(1)(stat)(2)(sys) Hz, which is consistent with the predicted effect of magnetic dipole-dipole interactions. These dipolar interactions may also account for the high magnon mass. The effective magnetic moment of -1.04(2)(stat)(8)(sys) times the atomic magnetic moment is consistent with mean-field theory.
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Affiliation(s)
- G Edward Marti
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Andrew MacRae
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Ryan Olf
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Sean Lourette
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Fang Fang
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Dan M Stamper-Kurn
- Department of Physics, University of California, Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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12
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Zhang Z, Duan LM. Generation of massive entanglement through an adiabatic quantum phase transition in a spinor condensate. PHYSICAL REVIEW LETTERS 2013; 111:180401. [PMID: 24237490 DOI: 10.1103/physrevlett.111.180401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Indexed: 06/02/2023]
Abstract
We propose a method to generate massive entanglement in a spinor Bose-Einstein condensate from an initial product state through an adiabatic sweep of the magnetic field across a quantum phase transition induced by competition between the spin-dependent collision interaction and the quadratic Zeeman effect. The generated many-body entanglement is characterized by the experimentally measurable entanglement depth in the proximity of the Dicke state. We show that the scheme is robust to practical noise and experimental imperfection and under realistic conditions it is possible to generate genuine entanglement for hundreds of atoms.
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Affiliation(s)
- Z Zhang
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA and Center for Quantum Information, IIIS, Tsinghua University, Beijing 100084, China
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13
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Smith A, Anderson BE, Sosa-Martinez H, Riofrío CA, Deutsch IH, Jessen PS. Quantum control in the Cs 6S(1/2) ground manifold using radio-frequency and microwave magnetic fields. PHYSICAL REVIEW LETTERS 2013; 111:170502. [PMID: 24206469 DOI: 10.1103/physrevlett.111.170502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Indexed: 06/02/2023]
Abstract
We implement arbitrary maps between pure states in the 16-dimensional Hilbert space associated with the ground electronic manifold of ^{133}Cs. This is accomplished by driving atoms with phase modulated radio-frequency and microwave fields, using modulation waveforms found via numerical optimization and designed to work robustly in the presence of imperfections. We evaluate the performance of a sample of randomly chosen state maps by randomized benchmarking, obtaining an average fidelity >99%. Our protocol advances state-of-the-art quantum control and has immediate applications in quantum metrology and tomography.
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Affiliation(s)
- A Smith
- Center for Quantum Information and Control, College of Optical Sciences and Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
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14
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Gajdacz M, Pedersen PL, Mørch T, Hilliard AJ, Arlt J, Sherson JF. Non-destructive Faraday imaging of dynamically controlled ultracold atoms. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:083105. [PMID: 24007051 DOI: 10.1063/1.4818913] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We describe an easily implementable method for non-destructive measurements of ultracold atomic clouds based on dark field imaging of spatially resolved Faraday rotation. The signal-to-noise ratio is analyzed theoretically and, in the absence of experimental imperfections, the sensitivity limit is found to be identical to other conventional dispersive imaging techniques. The dependence on laser detuning, atomic density, and temperature is characterized in a detailed comparison with theory. Due to low destructiveness, spatially resolved images of the same cloud can be acquired up to 2000 times. The technique is applied to avoid the effect of shot-to-shot fluctuations in atom number calibration, to demonstrate single-run vector magnetic field imaging and single-run spatial imaging of the system's dynamic behavior. This demonstrates that the method is a useful tool for the characterization of static and dynamically changing properties of ultracold atomic clouds.
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Affiliation(s)
- Miroslav Gajdacz
- Danish National Research Foundation Center for Quantum Optics, Institut for Fysik og Astronomi, Aarhus Universitet, Ny Munkegade 120, 8000 Aarhus C, Denmark
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15
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Bookjans EM, Hamley CD, Chapman MS. Strong quantum spin correlations observed in atomic spin mixing. PHYSICAL REVIEW LETTERS 2011; 107:210406. [PMID: 22181864 DOI: 10.1103/physrevlett.107.210406] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Indexed: 05/31/2023]
Abstract
We have observed sub-Poissonian spin correlations generated by collisionally induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum noise reduction of -7 dB (-10 dB corrected for detection noise) below the standard quantum limit for the corresponding coherent spin states. The spin fluctuations are detected as atom number differences in the spin states using fluorescent imaging that achieves a detection noise floor of 8 atoms per spin component for a probe time of 100 μs.
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Affiliation(s)
- Eva M Bookjans
- School of Physics, Georgia Institute of Technology, Atlanta, 30332-0430, USA
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16
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Bookjans EM, Vinit A, Raman C. Quantum phase transition in an antiferromagnetic spinor Bose-Einstein condensate. PHYSICAL REVIEW LETTERS 2011; 107:195306. [PMID: 22181622 DOI: 10.1103/physrevlett.107.195306] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Indexed: 05/31/2023]
Abstract
We have experimentally observed the dynamics of an antiferromagnetic sodium Bose-Einstein condensate quenched through a quantum phase transition. Using an off-resonant microwave field coupling the F = 1 and F = 2 atomic hyperfine levels, we rapidly switched the quadratic energy shift q from positive to negative values. At q = 0, the system undergoes a transition from a polar to antiferromagnetic phase. We measured the dynamical evolution of the population in the F = 1, mF = 0 state in the vicinity of this transition point and observed a mixed state of all 3 hyperfine components for q < 0. We also observed the coarsening dynamics of the instability for q < 0, as it nucleated small domains that grew to the axial size of the cloud.
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Affiliation(s)
- E M Bookjans
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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17
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Smith A, Anderson BE, Chaudhury S, Jessen PS. Three-axis measurement and cancellation of background magnetic fields to less than 50 µG in a cold atom experiment. JOURNAL OF PHYSICS B: ATOMIC, MOLECULAR AND OPTICAL PHYSICS 2011; 44:205002. [DOI: 10.1088/0953-4075/44/20/205002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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18
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Zhou L, Pu H, Ling HY, Zhang W. Cavity-mediated strong matter wave bistability in a spin-1 condensate. PHYSICAL REVIEW LETTERS 2009; 103:160403. [PMID: 19905675 DOI: 10.1103/physrevlett.103.160403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2009] [Indexed: 05/28/2023]
Abstract
We study matter-wave bistability in a spin-1 Bose-Einstein condensate dispersively coupled to a unidirectional ring cavity. A unique feature is that the population exchange among different modes of matter fields is accomplished via spin-exchange collisions. We show that the interplay between the atomic spin mixing and the cavity light field can lead to a strong matter-wave nonlinearity, making matter-wave bistability in a cavity at the single-photon level achievable.
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Affiliation(s)
- Lu Zhou
- State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China
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Liu Y, Gomez E, Maxwell SE, Turner LD, Tiesinga E, Lett PD. Number fluctuations and energy dissipation in sodium spinor condensates. PHYSICAL REVIEW LETTERS 2009; 102:225301. [PMID: 19658875 DOI: 10.1103/physrevlett.102.225301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 05/01/2009] [Indexed: 05/28/2023]
Abstract
We characterize fluctuations in atom number and spin populations in F=1 sodium spinor condensates. We find that the fluctuations enable a quantitative measure of energy dissipation in the condensate. The time evolution of the population fluctuations shows a maximum. We interpret this as evidence of a dissipation-driven separatrix crossing in phase space. For a given initial state, the critical time to the separatrix crossing is found to depend exponentially on the magnetic field and linearly on condensate density. This crossing is confirmed by tracking the energy of the spinor condensate as well as by Faraday rotation spectroscopy. We also introduce a phenomenological model that describes the observed dissipation with a single coefficient.
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Affiliation(s)
- Y Liu
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
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