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Delaney RD, Urmey MD, Mittal S, Brubaker BM, Kindem JM, Burns PS, Regal CA, Lehnert KW. Superconducting-qubit readout via low-backaction electro-optic transduction. Nature 2022; 606:489-493. [PMID: 35705821 DOI: 10.1038/s41586-022-04720-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 04/04/2022] [Indexed: 11/09/2022]
Abstract
Entangling microwave-frequency superconducting quantum processors through optical light at ambient temperature would enable means of secure communication and distributed quantum information processing1. However, transducing quantum signals between these disparate regimes of the electro-magnetic spectrum remains an outstanding goal2-9, and interfacing superconducting qubits, which are constrained to operate at millikelvin temperatures, with electro-optic transducers presents considerable challenges owing to the deleterious effects of optical photons on superconductors9,10. Moreover, many remote entanglement protocols11-14 require multiple qubit gates both preceding and following the upconversion of the quantum state, and thus an ideal transducer should impart minimal backaction15 on the qubit. Here we demonstrate readout of a superconducting transmon qubit through a low-backaction electro-optomechanical transducer. The modular nature of the transducer and circuit quantum electrodynamics system used in this work enable complete isolation of the qubit from optical photons, and the backaction on the qubit from the transducer is less than that imparted by thermal radiation from the environment. Moderate improvements in the transducer bandwidth and the added noise will enable us to leverage the full suite of tools available in circuit quantum electrodynamics to demonstrate transduction of non-classical signals from a superconducting qubit to the optical domain.
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Affiliation(s)
- R D Delaney
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA. .,Department of Physics, University of Colorado, Boulder, CO, USA.
| | - M D Urmey
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA.,Department of Physics, University of Colorado, Boulder, CO, USA
| | - S Mittal
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA.,Department of Physics, University of Colorado, Boulder, CO, USA
| | - B M Brubaker
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA.,Department of Physics, University of Colorado, Boulder, CO, USA
| | - J M Kindem
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA.,Department of Physics, University of Colorado, Boulder, CO, USA
| | - P S Burns
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA.,Department of Physics, University of Colorado, Boulder, CO, USA
| | - C A Regal
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA.,Department of Physics, University of Colorado, Boulder, CO, USA
| | - K W Lehnert
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO, USA.,Department of Physics, University of Colorado, Boulder, CO, USA.,National Institute of Standards and Technology, Boulder, CO, USA
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2
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Thiele T, Lin Y, Brown MO, Regal CA. Self-Calibrating Vector Atomic Magnetometry through Microwave Polarization Reconstruction. Phys Rev Lett 2018; 121:153202. [PMID: 30362778 DOI: 10.1103/physrevlett.121.153202] [Citation(s) in RCA: 2] [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: 07/08/2018] [Indexed: 06/08/2023]
Abstract
Atomic magnetometry is one of the most sensitive ways to measure magnetic fields. We present a method for converting a naturally scalar atomic magnetometer into a vector magnetometer by exploiting the polarization dependence of hyperfine transitions in rubidium atoms. First, we fully determine the polarization ellipse of an applied microwave field using a self-calibrating method, i.e., a method in which the light-atom interaction provides everything required to know the field in an orthogonal laboratory frame. We then measure the direction of an applied static field using the polarization ellipse as a three-dimensional reference defined by Maxwell's equations. Although demonstrated with trapped atoms, this technique could be applied to atomic vapors, or a variety of atomlike systems.
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Affiliation(s)
- T Thiele
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Y Lin
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - M O Brown
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - C A Regal
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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3
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Menke T, Burns PS, Higginbotham AP, Kampel NS, Peterson RW, Cicak K, Simmonds RW, Regal CA, Lehnert KW. Reconfigurable re-entrant cavity for wireless coupling to an electro-optomechanical device. Rev Sci Instrum 2017; 88:094701. [PMID: 28964202 DOI: 10.1063/1.5000973] [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] [Received: 03/27/2017] [Accepted: 08/20/2017] [Indexed: 06/07/2023]
Abstract
An electro-optomechanical device capable of microwave-to-optics conversion has recently been demonstrated, with the vision of enabling optical networks of superconducting qubits. Here we present an improved converter design that uses a three-dimensional microwave cavity for coupling between the microwave transmission line and an integrated LC resonator on the converter chip. The new design simplifies the optical assembly and decouples it from the microwave part of the setup. Experimental demonstrations show that the modular device assembly allows us to flexibly tune the microwave coupling to the converter chip while maintaining small loss. We also find that electromechanical experiments are not impacted by the additional microwave cavity. Our design is compatible with a high-finesse optical cavity and will improve optical performance.
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Affiliation(s)
- T Menke
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - P S Burns
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - A P Higginbotham
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - N S Kampel
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - R W Peterson
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - K Cicak
- National Institute of Standards and Technology (NIST), Boulder, Colorado 80305, USA
| | - R W Simmonds
- National Institute of Standards and Technology (NIST), Boulder, Colorado 80305, USA
| | - C A Regal
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - K W Lehnert
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
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4
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Peterson RW, Purdy TP, Kampel NS, Andrews RW, Yu PL, Lehnert KW, Regal CA. Laser Cooling of a Micromechanical Membrane to the Quantum Backaction Limit. Phys Rev Lett 2016; 116:063601. [PMID: 26918990 DOI: 10.1103/physrevlett.116.063601] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Indexed: 06/05/2023]
Abstract
The radiation pressure of light can act to damp and cool the vibrational motion of a mechanical resonator, but even if the light field has no thermal component, shot noise still sets a limit on the minimum phonon occupation. In optomechanical sideband cooling in a cavity, the finite off-resonant Stokes scattering defined by the cavity linewidth combined with shot noise fluctuations dictates a quantum backaction limit, analogous to the Doppler limit of atomic laser cooling. In our work, we sideband cool a micromechanical membrane resonator to the quantum backaction limit. Monitoring the optical sidebands allows us to directly observe the mechanical object come to thermal equilibrium with the optical bath. This level of optomechanical coupling that overwhelms the intrinsic thermal decoherence was not reached in previous ground-state cooling demonstrations.
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Affiliation(s)
- R W Peterson
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - T P Purdy
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - N S Kampel
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - R W Andrews
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - P-L Yu
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - K W Lehnert
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology (NIST), Boulder, Colorado 80305, USA
| | - C A Regal
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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5
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Kaufman AM, Lester BJ, Foss-Feig M, Wall ML, Rey AM, Regal CA. Entangling two transportable neutral atoms via local spin exchange. Nature 2015; 527:208-11. [PMID: 26524533 DOI: 10.1038/nature16073] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/30/2015] [Indexed: 11/09/2022]
Abstract
To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement, and have detected entanglement with macroscopic observables; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms. The local entangling operation is achieved via spin-exchange interactions, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.
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Affiliation(s)
- A M Kaufman
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA.,Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - B J Lester
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA.,Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - M Foss-Feig
- Joint Quantum Institute and the National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - M L Wall
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - A M Rey
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA.,Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - C A Regal
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA.,Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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6
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Kaufman AM, Lester BJ, Reynolds CM, Wall ML, Foss-Feig M, Hazzard KRA, Rey AM, Regal CA. Two-particle quantum interference in tunnel-coupled optical tweezers. Science 2014; 345:306-9. [DOI: 10.1126/science.1250057] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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7
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8
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Abstract
We study the mechanical quality factors of bilayer aluminum-silicon-nitride membranes. By coating ultrahigh-Q Si(3)N(4) membranes with a more lossy metal, we can precisely measure the effect of material loss on Q's of tensioned resonator modes over a large range of frequencies. We develop a theoretical model that interprets our results and predicts the damping can be reduced significantly by patterning the metal film. Using such patterning, we fabricate Al-Si(3)N(4) membranes with ultrahigh Q at room temperature. Our work elucidates the role of material loss in the Q of membrane resonators and informs the design of hybrid mechanical oscillators for optical-electrical-mechanical quantum interfaces.
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Affiliation(s)
- P-L Yu
- JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309, USA
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9
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10
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Chang DE, Regal CA, Papp SB, Wilson DJ, Ye J, Painter O, Kimble HJ, Zoller P. Cavity opto-mechanics using an optically levitated nanosphere. Proc Natl Acad Sci U S A 2010; 107:1005-10. [PMID: 20080573 PMCID: PMC2824320 DOI: 10.1073/pnas.0912969107] [Citation(s) in RCA: 439] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recently, remarkable advances have been made in coupling a number of high-Q modes of nano-mechanical systems to high-finesse optical cavities, with the goal of reaching regimes in which quantum behavior can be observed and leveraged toward new applications. To reach this regime, the coupling between these systems and their thermal environments must be minimized. Here we propose a novel approach to this problem, in which optically levitating a nano-mechanical system can greatly reduce its thermal contact, while simultaneously eliminating dissipation arising from clamping. Through the long coherence times allowed, this approach potentially opens the door to ground-state cooling and coherent manipulation of a single mesoscopic mechanical system or entanglement generation between spatially separate systems, even in room-temperature environments. As an example, we show that these goals should be achievable when the mechanical mode consists of the center-of-mass motion of a levitated nanosphere.
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Affiliation(s)
- D. E. Chang
- Institute for Quantum Information and Center for the Physics of Information, California Institute of Technology, Pasadena, CA 91125
| | - C. A. Regal
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125
| | - S. B. Papp
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125
| | - D. J. Wilson
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125
| | - J. Ye
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309
| | - O. Painter
- Department of Applied Physics, California Institute of Technology, Pasadena, CA 91125; and
| | - H. J. Kimble
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125
| | - P. Zoller
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
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11
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Abstract
We study high-stress SiN films for reaching the quantum regime with mesoscopic oscillators connected to a room-temperature thermal bath, for which there are stringent requirements on the oscillators' quality factors and frequencies. Our SiN films support mechanical modes with unprecedented products of mechanical quality factor Q(m) and frequency nu(m) reaching Q(m)nu(m) approximately or = 2 x 10(13) Hz. The SiN membranes exhibit a low optical absorption characterized by Im(n) < or approximately equal to 10(-5) at 935 nm, representing a 15 times reduction for SiN membranes. We have developed an apparatus to simultaneously cool the motion of multiple mechanical modes based on a short, high-finesse Fabry-Perot cavity and present initial cooling results along with future possibilities.
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Affiliation(s)
- D J Wilson
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125, USA
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12
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Aoki T, Parkins AS, Alton DJ, Regal CA, Dayan B, Ostby E, Vahala KJ, Kimble HJ. Efficient routing of single photons by one atom and a microtoroidal cavity. Phys Rev Lett 2009; 102:083601. [PMID: 19257737 DOI: 10.1103/physrevlett.102.083601] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Indexed: 05/27/2023]
Abstract
Single photons from a coherent input are efficiently redirected to a separate output by way of a fiber-coupled microtoroidal cavity interacting with individual cesium atoms. By operating in an overcoupled regime for the input-output to a tapered fiber, our system functions as a quantum router with high efficiency for photon sorting. Single photons are reflected and excess photons transmitted, as confirmed by observations of photon antibunching (bunching) for the reflected (transmitted) light. Our photon router is robust against large variations of atomic position and input power, with the observed photon antibunching persisting for intracavity photon number 0.03 < or approximately similar n < or approximately similar 0.7.
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Affiliation(s)
- Takao Aoki
- Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125, USA
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13
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Teufel JD, Harlow JW, Regal CA, Lehnert KW. Dynamical backaction of microwave fields on a nanomechanical oscillator. Phys Rev Lett 2008; 101:197203. [PMID: 19113301 DOI: 10.1103/physrevlett.101.197203] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Indexed: 05/22/2023]
Abstract
We measure the response and thermal motion of a high-Q nanomechanical oscillator coupled to a superconducting microwave cavity in the resolved-sideband regime where the oscillator's resonance frequency exceeds the cavity's linewidth. The coupling between the microwave field and mechanical motion is strong enough for radiation pressure to overwhelm the intrinsic mechanical damping. This radiation-pressure damping cools the fundamental mechanical mode by a factor of 5 below the thermal equilibrium temperature in a dilution refrigerator to a phonon occupancy of 140 quanta.
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Affiliation(s)
- J D Teufel
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309, USA.
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14
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Stewart JT, Gaebler JP, Regal CA, Jin DS. Potential energy of a 40K Fermi gas in the BCS-BEC crossover. Phys Rev Lett 2006; 97:220406. [PMID: 17155785 DOI: 10.1103/physrevlett.97.220406] [Citation(s) in RCA: 8] [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: 07/28/2006] [Indexed: 05/12/2023]
Abstract
We present a measurement of the potential energy of an ultracold trapped gas of 40K atoms in the BCS-BEC crossover and investigate the temperature dependence of this energy at a wide Feshbach resonance, where the gas is in the unitarity limit. In particular, we study the ratio of the potential energy in the region of the unitarity limit to that of a noninteracting gas, and in the T=0 limit we extract the universal many-body parameter beta. We find beta=-0.54_{-0.12};{+0.05}; this value is consistent with previous measurements using 6Li atoms and also with recent theory and Monte Carlo calculations. This result demonstrates the universality of ultracold Fermi gases in the strongly interacting regime.
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Affiliation(s)
- J T Stewart
- JILA, Quantum Physics Division, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA.
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15
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Regal CA, Greiner M, Giorgini S, Holland M, Jin DS. Momentum distribution of a Fermi gas of atoms in the BCS-BEC crossover. Phys Rev Lett 2005; 95:250404. [PMID: 16384438 DOI: 10.1103/physrevlett.95.250404] [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: 07/12/2005] [Indexed: 05/05/2023]
Abstract
We observe dramatic changes in the atomic momentum distribution of a Fermi gas in the crossover region between the BCS theory superconductivity and Bose-Einstein condensation (BEC) of molecules. We study the shape of the momentum distribution and the kinetic energy as a function of interaction strength. The momentum distributions are compared to a mean-field crossover theory, and the kinetic energy is compared to theories for the two weakly interacting limits. This measurement provides a unique probe of pairing in a strongly interacting Fermi gas.
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Affiliation(s)
- C A Regal
- JILA, Quantum Physics Division, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA.
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16
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Hodby E, Thompson ST, Regal CA, Greiner M, Wilson AC, Jin DS, Cornell EA, Wieman CE. Production efficiency of ultracold feshbach molecules in bosonic and fermionic systems. Phys Rev Lett 2005; 94:120402. [PMID: 15903898 DOI: 10.1103/physrevlett.94.120402] [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: 11/17/2004] [Indexed: 05/02/2023]
Abstract
We investigate the production efficiency of ultracold molecules in bosonic 85Rb and fermionic 40K when the magnetic field is swept across a Feshbach resonance. For adiabatic sweeps of the magnetic field, our novel model shows that the conversion efficiency of both species is solely determined by the phase space density of the atomic cloud, in contrast with a number of theoretical predictions. In the nonadiabatic regime our measurements of the 85Rb molecule conversion efficiency follow a Landau-Zener model.
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Affiliation(s)
- E Hodby
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA
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17
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Greiner M, Regal CA, Stewart JT, Jin DS. Probing pair-correlated fermionic atoms through correlations in atom shot noise. Phys Rev Lett 2005; 94:110401. [PMID: 15903831 DOI: 10.1103/physrevlett.94.110401] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Indexed: 05/02/2023]
Abstract
Pair-correlated fermionic atoms are created through dissociation of weakly bound molecules near a magnetic-field Feshbach resonance. We show that correlations between atoms in different spin states can be detected using the atom shot noise in absorption images. Furthermore, using time-of-flight imaging we have observed atom pair correlations in momentum space.
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Affiliation(s)
- M Greiner
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, CO 80309-0440, USA.
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18
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Greiner M, Regal CA, Jin DS. Probing the excitation spectrum of a fermi gas in the BCS-BEC crossover regime. Phys Rev Lett 2005; 94:070403. [PMID: 15783792 DOI: 10.1103/physrevlett.94.070403] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Indexed: 05/24/2023]
Abstract
We measure excitation spectra of an ultracold gas of fermionic (40)K atoms in the BCS-Bose-Einstein-condensation (BEC) crossover regime. The measurements are performed with a novel spectroscopy that employs a small modulation of the B field close to a Feshbach resonance to give rise to a modulation of the interaction strength. With this method we observe both a collective excitation as well as the dissociation of fermionic atom pairs in the strongly interacting regime. The excitation spectra reveal the binding energy or excitation gap for pairs in the crossover region.
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Affiliation(s)
- M Greiner
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA.
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19
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Greiner M, Regal CA, Ticknor C, Bohn JL, Jin DS. Detection of spatial correlations in an ultracold gas of fermions. Phys Rev Lett 2004; 92:150405. [PMID: 15169273 DOI: 10.1103/physrevlett.92.150405] [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: 08/26/2003] [Indexed: 05/24/2023]
Abstract
Spatial correlations are observed in an ultracold gas of fermionic atoms close to a Feshbach resonance. The correlations are detected by inducing spin-changing rf transitions between pairs of atoms. We observe the process in the strongly interacting regime for attractive as well as for repulsive atom-atom interactions and both in the regime of high and low quantum degeneracy. The observations are compared with a two-particle model that provides theoretical predictions for the measured rf transition rates.
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Affiliation(s)
- M Greiner
- JILA, University of Colorado and National Institute of Standards and Technology, Department of Physics, Boulder, Colorado 80309-0440, USA.
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20
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Abstract
We report a dramatic magnetic-field dependence in the lifetime of trapped, ultracold diatomic molecules created through an s-wave Feshbach resonance between fermionic atoms. The molecule lifetime increases from less than 1 ms away from the Feshbach resonance to greater than 100 ms near resonance. We also have measured the trapped atom lifetime as a function of magnetic field near the Feshbach resonance; we find that the atom loss is more pronounced on the side of the resonance containing the molecular bound state.
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Affiliation(s)
- C A Regal
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
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21
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Abstract
We have observed condensation of fermionic atom pairs in the BCS-BEC crossover regime. A trapped gas of fermionic 40K atoms is evaporatively cooled to quantum degeneracy and then a magnetic-field Feshbach resonance is used to control the atom-atom interactions. The location of this resonance is precisely determined from low-density measurements of molecule dissociation. In order to search for condensation on either side of the resonance, we introduce a technique that pairwise projects fermionic atoms onto molecules; this enables us to measure the momentum distribution of fermionic atom pairs. The transition to condensation of fermionic atom pairs is mapped out as a function of the initial atom gas temperature T compared to the Fermi temperature T(F) for magnetic-field detunings on both the BCS and BEC sides of the resonance.
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Affiliation(s)
- C A Regal
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, CO 80309-0440, USA
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22
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Abstract
We report on progress toward realizing a predicted superfluid phase in a Fermi gas of atoms. We present measurements of both large positive and large negative scattering lengths in a quantum degenerate Fermi gas of atoms near a magnetic-field Feshbach resonance. We employ an rf spectroscopy technique to directly measure the mean-field interaction energy, which is proportional to the s-wave scattering length. Near the peak of the resonance we observe a saturation of the interaction energy; it is in this strongly interacting regime that superfluidity is predicted to occur. We have also observed anisotropic expansion of the gas, which has recently been suggested as a signature of superfluidity. However, we find that this can be attributed to a purely collisional effect.
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Affiliation(s)
- C A Regal
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, CO 80309-0440, USA
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Abstract
We have measured a p-wave Feshbach resonance in a single-component, ultracold Fermi gas of 40K atoms. We have used this resonance to enhance the normally suppressed p-wave collision cross section to values larger than the background s-wave cross section between 40K atoms in different spin states. In addition to the modification of two-body elastic processes, the resonance dramatically enhances three-body inelastic collisional loss.
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Affiliation(s)
- C A Regal
- JILA, National Institute of Standards and Technology, Boulder, Colorado 80309-0440, USA
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Loftus T, Regal CA, Ticknor C, Bohn JL, Jin DS. Resonant control of elastic collisions in an optically trapped fermi gas of atoms. Phys Rev Lett 2002; 88:173201. [PMID: 12005753 DOI: 10.1103/physrevlett.88.173201] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2001] [Indexed: 05/23/2023]
Abstract
We have loaded an ultracold gas of fermionic atoms into a far-off resonance optical dipole trap and precisely controlled the spin composition of the trapped gas. We have measured a magnetic-field Feshbach resonance between atoms in the two lowest energy spin states, /9/2,-9/2> and /9/2,-7/2>. The resonance peaks at a magnetic field of 201.5+/-1.4 G and has a width of 8.0+/-1.1 G. Using this resonance, we have changed the elastic collision cross section in the gas by nearly 3 orders of magnitude.
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Affiliation(s)
- T Loftus
- JILA, National Institute of Standards and Technology, University of Colorado, Boulder, Colorado 80309, USA
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Anderson BP, Haljan PC, Regal CA, Feder DL, Collins LA, Clark CW, Cornell EA. Watching dark solitons decay into vortex rings in a Bose-Einstein condensate. Phys Rev Lett 2001; 86:2926-2929. [PMID: 11290074 DOI: 10.1103/physrevlett.86.2926] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2000] [Indexed: 05/23/2023]
Abstract
We have created spatial dark solitons in two-component Bose-Einstein condensates in which the soliton exists in one of the condensate components and the soliton nodal plane is filled with the second component. The filled solitons are stable for hundreds of milliseconds. The filling can be selectively removed, making the soliton more susceptible to dynamical instabilities. For a condensate in a spherically symmetric potential, these instabilities cause the dark soliton to decay into stable vortex rings. We have imaged the resulting vortex rings.
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Affiliation(s)
- B P Anderson
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder 80309-0440, USA
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