1
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Lewis-Swan RJ, Castro JCZ, Barberena D, Rey AM. Exploiting Nonclassical Motion of a Trapped Ion Crystal for Quantum-Enhanced Metrology of Global and Differential Spin Rotations. PHYSICAL REVIEW LETTERS 2024; 132:163601. [PMID: 38701452 DOI: 10.1103/physrevlett.132.163601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/23/2024] [Accepted: 03/18/2024] [Indexed: 05/05/2024]
Abstract
We theoretically investigate prospects for the creation of nonclassical spin states in trapped ion arrays by coupling to a squeezed state of the collective motion of the ions. The correlations of the generated spin states can be tailored for quantum-enhanced sensing of global or differential rotations of subensembles of the spins by working with specific vibrational modes of the ion array. We propose a pair of protocols to utilize the generated states and demonstrate their viability even for small systems, while assessing limitations imposed by spin-motion entanglement and technical noise. Our work suggests new opportunities for the preparation of many-body states with tailored correlations for quantum-enhanced metrology in spin-boson systems.
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Affiliation(s)
- R J Lewis-Swan
- Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman, Oklahoma 73019, USA
- Center for Quantum Research and Technology, The University of Oklahoma, Norman, Oklahoma 73019, USA
| | - J C Zuñiga Castro
- Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman, Oklahoma 73019, USA
- Center for Quantum Research and Technology, The University of Oklahoma, Norman, Oklahoma 73019, USA
| | - D Barberena
- JILA, NIST, and Department of Physics, University of Colorado, Boulder, Colorado, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado, USA
| | - A M Rey
- JILA, NIST, and Department of Physics, University of Colorado, Boulder, Colorado, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado, USA
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2
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Hotter C, Ritsch H, Gietka K. Combining Critical and Quantum Metrology. PHYSICAL REVIEW LETTERS 2024; 132:060801. [PMID: 38394596 DOI: 10.1103/physrevlett.132.060801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 01/16/2024] [Indexed: 02/25/2024]
Abstract
Critical metrology relies on the precise preparation of a system in its ground state near a quantum phase transition point where quantum correlations get very strong. Typically, this increases the quantum Fisher information with respect to changes in system parameters and thus improves the optimally possible measurement precision limited by the Cramér-Rao bound. Hence critical metrology involves encoding information about the unknown parameter in changes of the system's ground state. Conversely, in conventional metrology methods like Ramsey interferometry, the eigenstates of the system remain unchanged, and information about the unknown parameter is encoded in the relative phases that excited system states accumulate during their time evolution. Here we introduce an approach combining these two methodologies into a unified protocol applicable to closed and driven-dissipative systems. We show that the quantum Fisher information in this case exhibits an additional interference term originating from the interplay between eigenstate and relative phase changes. We provide analytical expressions for the quantum and classical Fisher information in such a setup, elucidating as well a straightforward measurement approach that nearly attains the maximum precision permissible under the Cramér-Rao bound. We showcase these results by focusing on the squeezing Hamiltonian, which characterizes the thermodynamic limit of Dicke and Lipkin-Meshkov-Glick Hamiltonians.
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Affiliation(s)
- Christoph Hotter
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Helmut Ritsch
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Karol Gietka
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
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3
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Koppenhöfer M, Groszkowski P, Clerk AA. Squeezed Superradiance Enables Robust Entanglement-Enhanced Metrology Even with Highly Imperfect Readout. PHYSICAL REVIEW LETTERS 2023; 131:060802. [PMID: 37625053 DOI: 10.1103/physrevlett.131.060802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/20/2023] [Accepted: 07/14/2023] [Indexed: 08/27/2023]
Abstract
Quantum metrology protocols using entangled states of large spin ensembles attempt to achieve measurement sensitivities surpassing the standard quantum limit (SQL), but in many cases they are severely limited by even small amounts of technical noise associated with imperfect sensor readout. Amplification strategies based on time-reversed coherent spin-squeezing dynamics have been devised to mitigate this issue, but are unfortunately very sensitive to dissipation, requiring a large single-spin cooperativity to be effective. Here, we propose a new dissipative protocol that combines amplification and squeezed fluctuations. It enables the use of entangled spin states for sensing well beyond the SQL even in the presence of significant readout noise. Further, it has a strong resilience against undesired single-spin dissipation, requiring only a large collective cooperativity to be effective.
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Affiliation(s)
- Martin Koppenhöfer
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Peter Groszkowski
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- National Center for Computational Sciences, Oak Ridge National Laboratory, Tennessee 37831, USA
| | - A A Clerk
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
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4
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Li Z, Colombo S, Shu C, Velez G, Pilatowsky-Cameo S, Schmied R, Choi S, Lukin M, Pedrozo-Peñafiel E, Vuletić V. Improving metrology with quantum scrambling. Science 2023; 380:1381-1384. [PMID: 37384680 DOI: 10.1126/science.adg9500] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/19/2023] [Indexed: 07/01/2023]
Abstract
Quantum scrambling describes the spreading of information into many degrees of freedom in quantum systems, such that the information is no longer accessible locally but becomes distributed throughout the system. This idea can explain how quantum systems become classical and acquire a finite temperature, or how in black holes the information about the matter falling in is seemingly erased. We probe the exponential scrambling of a multiparticle system near a bistable point in phase space and utilize it for entanglement-enhanced metrology. A time-reversal protocol is used to observe a simultaneous exponential growth of both the metrological gain and the out-of-time-order correlator, thereby experimentally verifying the relation between quantum metrology and quantum information scrambling. Our results show that rapid scrambling dynamics capable of exponentially fast entanglement generation are useful for practical metrology, resulting in a 6.8(4)-decibel gain beyond the standard quantum limit.
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Affiliation(s)
- Zeyang Li
- Department of Physics, MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Simone Colombo
- Department of Physics, MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chi Shu
- Department of Physics, MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Gustavo Velez
- Department of Physics, MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Saúl Pilatowsky-Cameo
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Soonwon Choi
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mikhail Lukin
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Edwin Pedrozo-Peñafiel
- Department of Physics, MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Vladan Vuletić
- Department of Physics, MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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5
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Mehdi Z, Hope JJ, Haine SA. Signatures of Quantum Gravity in the Gravitational Self-Interaction of Photons. PHYSICAL REVIEW LETTERS 2023; 130:240203. [PMID: 37390411 DOI: 10.1103/physrevlett.130.240203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 03/15/2023] [Accepted: 05/05/2023] [Indexed: 07/02/2023]
Abstract
We propose relativistic tests of quantum gravity using the gravitational self-interaction of photons in a cavity. We demonstrate that this interaction results in a number of quantum gravitational signatures in the quantum state of the light that cannot be reproduced by any classical theory of gravity. We rigorously assess these effects using quantum parameter estimation theory and discuss simple measurement schemes that optimally extract their signatures. Crucially, the proposed tests are free of QED photon-photon scattering, are sensitive to the spin of the mediating gravitons, and can probe the locality of the gravitational interaction. These protocols provide a new avenue for studying the quantum nature of gravity in a relativistic setting.
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Affiliation(s)
- Zain Mehdi
- Department of Quantum Science and Technology and Department of Fundamental and Theoretical Physics, Research School of Physics, Australian National University, Canberra 2600, Australia
| | - Joseph J Hope
- Department of Quantum Science and Technology and Department of Fundamental and Theoretical Physics, Research School of Physics, Australian National University, Canberra 2600, Australia
| | - Simon A Haine
- Department of Quantum Science and Technology and Department of Fundamental and Theoretical Physics, Research School of Physics, Australian National University, Canberra 2600, Australia
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6
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Gietka K, Ritsch H. Squeezing and Overcoming the Heisenberg Scaling with Spin-Orbit Coupled Quantum Gases. PHYSICAL REVIEW LETTERS 2023; 130:090802. [PMID: 36930939 DOI: 10.1103/physrevlett.130.090802] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
We predict that exploiting spin-orbit coupling in a harmonically trapped spinor quantum gas can lead to scaling of the optimal measurement precision beyond the Heisenberg scaling. We show that quadratic scaling with the number of atoms can be facilitated via squeezed center-of-mass excitations of the atomic motion using 1D spin-orbit coupled fermions or strongly interacting bosons (Tonks-Girardeau gas). Based on predictions derived from analytic calculations of the corresponding quantum Fisher information, we then introduce a protocol which overcomes the Heisenberg scaling (and limit) with the help of a tailored excited and entangled many-body state of a noninteracting Bose-Einstein condensate. We identify corresponding optimal measurements and argue that even finite temperature as a source of decoherence is, in principle, rather favorable for the obtainable precision scaling.
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Affiliation(s)
- Karol Gietka
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
- Quantum Systems Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Helmut Ritsch
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
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7
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Abstract
The impact of measurement imperfections on quantum metrology protocols has not been approached in a systematic manner so far. In this work, we tackle this issue by generalising firstly the notion of quantum Fisher information to account for noisy detection, and propose tractable methods allowing for its approximate evaluation. We then show that in canonical scenarios involving N probes with local measurements undergoing readout noise, the optimal sensitivity depends crucially on the control operations allowed to counterbalance the measurement imperfections—with global control operations, the ideal sensitivity (e.g., the Heisenberg scaling) can always be recovered in the asymptotic N limit, while with local control operations the quantum-enhancement of sensitivity is constrained to a constant factor. We illustrate our findings with an example of NV-centre magnetometry, as well as schemes involving spin-1/2 probes with bit-flip errors affecting their two-outcome measurements, for which we find the input states and control unitary operations sufficient to attain the ultimate asymptotic precision. The effects of detection noise on quantum metrology performances have not been rigorously investigated yet. Here, the authors fill this gap by generalising the quantum Fisher information to the case of noisy readout, and showing the consequences the imperfect measurements bring.
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8
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Corgier R, Gaaloul N, Smerzi A, Pezzè L. Delta-Kick Squeezing. PHYSICAL REVIEW LETTERS 2021; 127:183401. [PMID: 34767389 DOI: 10.1103/physrevlett.127.183401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
We explore the possibility to overcome the standard quantum limit (SQL) in a free-fall atom interferometer using a Bose-Einstein condensate (BEC) in either of the two relevant cases of Bragg or Raman scattering light pulses. The generation of entanglement in the BEC is dramatically enhanced by amplifying the atom-atom interactions via the rapid action of an external trap, focusing the matter waves to significantly increase the atomic densities during a preparation stage-a technique we refer to as delta-kick squeezing (DKS). The action of a second DKS operation at the end of the interferometry sequence allows one to implement a nonlinear readout scheme, making the sub-SQL sensitivity highly robust against imperfect atom counting detection. We predict more than 30 dB of sensitivity gain beyond the SQL for the variance, assuming realistic parameters and 10^{6} atoms.
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Affiliation(s)
- Robin Corgier
- QSTAR, INO-CNR and LENS, Largo Enrico Fermi 2, 50125 Firenze, Italy
| | - Naceur Gaaloul
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
| | - Augusto Smerzi
- QSTAR, INO-CNR and LENS, Largo Enrico Fermi 2, 50125 Firenze, Italy
| | - Luca Pezzè
- QSTAR, INO-CNR and LENS, Largo Enrico Fermi 2, 50125 Firenze, Italy
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9
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Baamara Y, Sinatra A, Gessner M. Scaling Laws for the Sensitivity Enhancement of Non-Gaussian Spin States. PHYSICAL REVIEW LETTERS 2021; 127:160501. [PMID: 34723607 DOI: 10.1103/physrevlett.127.160501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
We identify the large-N scaling of the metrological quantum gain offered by over-squeezed spin states that are accessible by one-axis twisting, as a function of the preparation time. We further determine how the scaling is modified by relevant decoherence processes and predict a discontinuous change of the quantum gain at a critical preparation time that depends on the noise. Our analytical results provide recipes for optimal and feasible implementations of quantum enhancements with non-Gaussian spin states in existing experiments, well beyond the reach of spin squeezing.
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Affiliation(s)
- Youcef Baamara
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 24 Rue Lhomond, 75005 Paris, France
| | - Alice Sinatra
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 24 Rue Lhomond, 75005 Paris, France
| | - Manuel Gessner
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 24 Rue Lhomond, 75005 Paris, France
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10
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Gilmore KA, Affolter M, Lewis-Swan RJ, Barberena D, Jordan E, Rey AM, Bollinger JJ. Quantum-enhanced sensing of displacements and electric fields with two-dimensional trapped-ion crystals. Science 2021; 373:673-678. [PMID: 34353950 DOI: 10.1126/science.abi5226] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 06/25/2021] [Indexed: 11/02/2022]
Abstract
Fully controllable ultracold atomic systems are creating opportunities for quantum sensing, yet demonstrating a quantum advantage in useful applications by harnessing entanglement remains a challenging task. Here, we realize a many-body quantum-enhanced sensor to detect displacements and electric fields using a crystal of ~150 trapped ions. The center-of-mass vibrational mode of the crystal serves as a high-Q mechanical oscillator, and the collective electronic spin serves as the measurement device. By entangling the oscillator and collective spin and controlling the coherent dynamics via a many-body echo, a displacement is mapped into a spin rotation while avoiding quantum back-action and thermal noise. We achieve a sensitivity to displacements of 8.8 ± 0.4 decibels below the standard quantum limit and a sensitivity for measuring electric fields of 240 ± 10 nanovolts per meter in 1 second. Feasible improvements should enable the use of trapped ions in searches for dark matter.
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Affiliation(s)
- Kevin A Gilmore
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA. .,Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA.,National Institute of Standards and Technology, Boulder, CO 80305, USA.,Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Matthew Affolter
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA.,National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Robert J Lewis-Swan
- National Institute of Standards and Technology, Boulder, CO 80305, USA.,Department of Physics, University of Colorado, Boulder, CO 80309, USA.,Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA.,Center for Quantum Research and Technology, University of Oklahoma, Norman, OK 73019, USA
| | - Diego Barberena
- Center for Quantum Research and Technology, University of Oklahoma, Norman, OK 73019, USA.,JILA, NIST, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.,JILA, NIST, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.,Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA
| | - Elena Jordan
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA.,National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Ana Maria Rey
- Center for Quantum Research and Technology, University of Oklahoma, Norman, OK 73019, USA. .,JILA, NIST, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.,JILA, NIST, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.,Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA
| | - John J Bollinger
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA. .,National Institute of Standards and Technology, Boulder, CO 80305, USA
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11
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Lewis-Swan RJ, Barberena D, Muniz JA, Cline JRK, Young D, Thompson JK, Rey AM. Protocol for Precise Field Sensing in the Optical Domain with Cold Atoms in a Cavity. PHYSICAL REVIEW LETTERS 2020; 124:193602. [PMID: 32469538 DOI: 10.1103/physrevlett.124.193602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 04/08/2020] [Indexed: 06/11/2023]
Abstract
In the context of quantum metrology, optical cavity-QED platforms have primarily been focused on the generation of entangled atomic spin states useful for next-generation frequency and time standards. Here, we report a complementary application: the use of optical cavities to generate nonclassical states of light for electric field sensing below the standard quantum limit. We show that cooperative atom-light interactions in the strong collective coupling regime can be used to engineer generalized atom-light cat states which enable quantum enhanced sensing of small displacements of the cavity field even in the presence of photon loss. We demonstrate that metrological gains of 10-20 dB below the standard quantum limit are within reach for current cavity-QED systems operating with long-lived alkaline-earth atoms.
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Affiliation(s)
- Robert J Lewis-Swan
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Diego Barberena
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Juan A Muniz
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Julia R K Cline
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Dylan Young
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - James K Thompson
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ana Maria Rey
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
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12
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Haine SA, Hope JJ. Machine-Designed Sensor to Make Optimal Use of Entanglement-Generating Dynamics for Quantum Sensing. PHYSICAL REVIEW LETTERS 2020; 124:060402. [PMID: 32109102 DOI: 10.1103/physrevlett.124.060402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 01/29/2020] [Indexed: 06/10/2023]
Abstract
We use machine optimization to develop a quantum sensing scheme that achieves significantly better sensitivity than traditional schemes with the same quantum resources. Utilizing one-axis twisting dynamics to generate quantum entanglement, we find that, rather than dividing the temporal resources into separate "state-preparation" and "interrogation" stages, a complicated machine-designed sequence of rotations allows for the generation of metrologically useful entanglement while the parameter is interrogated. This provides much higher sensitivities for a given total time compared to states generated via traditional one-axis twisting schemes. This approach could be applied to other methods of generating quantum-enhanced states, allowing for atomic clocks, magnetometers, and inertial sensors with increased sensitivities.
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Affiliation(s)
- Simon A Haine
- Department of Quantum Science, Research School of Physics, Australian National University, Canberra, ACT 0200, Australia
| | - Joseph J Hope
- Department of Quantum Science, Research School of Physics, Australian National University, Canberra, ACT 0200, Australia
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13
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Lucchesi L, Chiofalo ML. Many-Body Entanglement in Short-Range Interacting Fermi Gases for Metrology. PHYSICAL REVIEW LETTERS 2019; 123:060406. [PMID: 31491136 DOI: 10.1103/physrevlett.123.060406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/20/2019] [Indexed: 06/10/2023]
Abstract
We explore many-body entanglement in spinful Fermi gases with short-range interactions, for metrology purposes. We characterize the emerging quantum phases via density-matrix renormalization group simulations and quantify their entanglement content for metrological usability via quantum Fisher information (QFI). Our study establishes a method, promoting QFI to be an order parameter. Short-range interactions reveal to build up metrologically promising entanglement in the XY-ferromagnetic and cluster ordering, the cluster physics being unexplored so far.
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Affiliation(s)
- Leonardo Lucchesi
- Dipartimento di Fisica "Enrico Fermi" and INFN, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - Maria Luisa Chiofalo
- Dipartimento di Fisica "Enrico Fermi" and INFN, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- JILA, University of Colorado, 440 UCB, Boulder, Colorado 80309, USA
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030, USA
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14
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Evrard A, Makhalov V, Chalopin T, Sidorenkov LA, Dalibard J, Lopes R, Nascimbene S. Enhanced Magnetic Sensitivity with Non-Gaussian Quantum Fluctuations. PHYSICAL REVIEW LETTERS 2019; 122:173601. [PMID: 31107084 DOI: 10.1103/physrevlett.122.173601] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Indexed: 06/09/2023]
Abstract
The precision of a quantum sensor can overcome its classical counterpart when its constituents are entangled. In Gaussian squeezed states, quantum correlations lead to a reduction of the quantum projection noise below the shot noise limit. However, the most sensitive states involve complex non-Gaussian quantum fluctuations, making the required measurement protocol challenging. Here we measure the sensitivity of nonclassical states of the electronic spin J=8 of dysprosium atoms, created using light-induced nonlinear spin coupling. Magnetic sublevel resolution enables us to reach the optimal sensitivity of non-Gaussian (oversqueezed) states, well above the capability of squeezed states and about half the Heisenberg limit.
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Affiliation(s)
- Alexandre Evrard
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Vasiliy Makhalov
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Thomas Chalopin
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Leonid A Sidorenkov
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Jean Dalibard
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Raphael Lopes
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Sylvain Nascimbene
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
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15
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Quantum-enhanced sensing using non-classical spin states of a highly magnetic atom. Nat Commun 2018; 9:4955. [PMID: 30470745 PMCID: PMC6251866 DOI: 10.1038/s41467-018-07433-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/26/2018] [Indexed: 11/08/2022] Open
Abstract
Coherent superposition states of a mesoscopic quantum object play a major role in our understanding of the quantum to classical boundary, as well as in quantum-enhanced metrology and computing. However, their practical realization and manipulation remains challenging, requiring a high degree of control of the system and its coupling to the environment. Here, we use dysprosium atoms-the most magnetic element in its ground state-to realize coherent superpositions between electronic spin states of opposite orientation, with a mesoscopic spin size J = 8. We drive coherent spin states to quantum superpositions using non-linear light-spin interactions, observing a series of collapses and revivals of quantum coherence. These states feature highly non-classical behavior, with a sensitivity to magnetic fields enhanced by a factor 13.9(1.1) compared to coherent spin states-close to the Heisenberg limit 2J = 16-and an intrinsic fragility to environmental noise.
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