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Roscilde T, Comparin T, Mezzacapo F. Entangling Dynamics from Effective Rotor-Spin-Wave Separation in U(1)-Symmetric Quantum Spin Models. PHYSICAL REVIEW LETTERS 2023; 131:160403. [PMID: 37925736 DOI: 10.1103/physrevlett.131.160403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 07/14/2023] [Accepted: 09/05/2023] [Indexed: 11/07/2023]
Abstract
The nonequilibrium dynamics of quantum spin models is a most challenging topic, due to the exponentiality of Hilbert space, and it is central to the understanding of the many-body entangled states that can be generated by state-of-the-art quantum simulators. A particularly important class of evolutions is the one governed by U(1)-symmetric Hamiltonians, initialized in a state that breaks the U(1) symmetry-the paradigmatic example being the evolution of the so-called one-axis-twisting (OAT) model, featuring infinite-range interactions between spins. In this Letter, we show that the dynamics of the OAT model can be closely reproduced by systems with power-law-decaying interactions, thanks to an effective separation between the zero-momentum degrees of freedom, associated with the so-called Anderson tower of states, and reconstructing an OAT model, as well as finite-momentum ones, associated with spin-wave excitations. This mechanism explains quantitatively the recent numerical observation of spin squeezing and Schrödinger cat-state generation in the dynamics of dipolar Hamiltonians, and it paves the way for the extension of this observation to a much larger class of models of immediate relevance for quantum simulations.
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Affiliation(s)
- Tommaso Roscilde
- Univ Lyon, Ens de Lyon, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - Tommaso Comparin
- Univ Lyon, Ens de Lyon, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - Fabio Mezzacapo
- Univ Lyon, Ens de Lyon, CNRS, Laboratoire de Physique, F-69342 Lyon, France
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Franke J, Muleady SR, Kaubruegger R, Kranzl F, Blatt R, Rey AM, Joshi MK, Roos CF. Quantum-enhanced sensing on optical transitions through finite-range interactions. Nature 2023; 621:740-745. [PMID: 37648868 DOI: 10.1038/s41586-023-06472-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 07/21/2023] [Indexed: 09/01/2023]
Abstract
The control over quantum states in atomic systems has led to the most precise optical atomic clocks so far1-3. Their sensitivity is bounded at present by the standard quantum limit, a fundamental floor set by quantum mechanics for uncorrelated particles, which can-nevertheless-be overcome when operated with entangled particles. Yet demonstrating a quantum advantage in real-world sensors is extremely challenging. Here we illustrate a pathway for harnessing large-scale entanglement in an optical transition using 1D chains of up to 51 ions with interactions that decay as a power-law function of the ion separation. We show that our sensor can emulate many features of the one-axis-twisting (OAT) model, an iconic, fully connected model known to generate scalable squeezing4 and Greenberger-Horne-Zeilinger-like states5-8. The collective nature of the state manifests itself in the preservation of the total transverse magnetization, the reduced growth of the structure factor, that is, spin-wave excitations (SWE), at finite momenta, the generation of spin squeezing comparable with OAT (a Wineland parameter9,10 of -3.9 ± 0.3 dB for only N = 12 ions) and the development of non-Gaussian states in the form of multi-headed cat states in the Q-distribution. We demonstrate the metrological utility of the states in a Ramsey-type interferometer, in which we reduce the measurement uncertainty by -3.2 ± 0.5 dB below the standard quantum limit for N = 51 ions.
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Affiliation(s)
- Johannes Franke
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Sean R Muleady
- JILA, NIST and Department of Physics, University of Colorado, Boulder, CO, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA
| | - Raphael Kaubruegger
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
- Institut für Theoretische Physik, Universität Innsbruck, Innsbruck, Austria
| | - Florian Kranzl
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Rainer Blatt
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Ana Maria Rey
- JILA, NIST and Department of Physics, University of Colorado, Boulder, CO, USA.
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA.
| | - Manoj K Joshi
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Christian F Roos
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria.
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria.
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Bornet G, Emperauger G, Chen C, Ye B, Block M, Bintz M, Boyd JA, Barredo D, Comparin T, Mezzacapo F, Roscilde T, Lahaye T, Yao NY, Browaeys A. Scalable spin squeezing in a dipolar Rydberg atom array. Nature 2023; 621:728-733. [PMID: 37648859 DOI: 10.1038/s41586-023-06414-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 07/07/2023] [Indexed: 09/01/2023]
Abstract
The standard quantum limit bounds the precision of measurements that can be achieved by ensembles of uncorrelated particles. Fundamentally, this limit arises from the non-commuting nature of quantum mechanics, leading to the presence of fluctuations often referred to as quantum projection noise. Quantum metrology relies on the use of non-classical states of many-body systems to enhance the precision of measurements beyond the standard quantum limit1,2. To do so, one can reshape the quantum projection noise-a strategy known as squeezing3,4. In the context of many-body spin systems, one typically uses all-to-all interactions (for example, the one-axis twisting model4) between the constituents to generate the structured entanglement characteristic of spin squeezing5. Here we explore the prediction, motivated by recent theoretical work6-10, that short-range interactions-and in particular, the two-dimensional dipolar XY model-can also enable the realization of scalable spin squeezing. Working with a dipolar Rydberg quantum simulator of up to N = 100 atoms, we demonstrate that quench dynamics from a polarized initial state lead to spin squeezing that improves with increasing system size up to a maximum of -3.5 ± 0.3 dB (before correcting for detection errors, or roughly -5 ± 0.3 dB after correction). Finally, we present two independent refinements: first, using a multistep spin-squeezing protocol allows us to further enhance the squeezing by roughly 1 dB, and second, leveraging Floquet engineering to realize Heisenberg interactions, we demonstrate the ability to extend the lifetime of the squeezed state by freezing its dynamics.
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Affiliation(s)
- Guillaume Bornet
- Charles Fabry Laboratory University of Paris-Saclay, Institute of Optics Graduate School, CNRS, Palaiseau Cedex, France
| | - Gabriel Emperauger
- Charles Fabry Laboratory University of Paris-Saclay, Institute of Optics Graduate School, CNRS, Palaiseau Cedex, France
| | - Cheng Chen
- Charles Fabry Laboratory University of Paris-Saclay, Institute of Optics Graduate School, CNRS, Palaiseau Cedex, France.
| | - Bingtian Ye
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Maxwell Block
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Marcus Bintz
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Jamie A Boyd
- Charles Fabry Laboratory University of Paris-Saclay, Institute of Optics Graduate School, CNRS, Palaiseau Cedex, France
| | - Daniel Barredo
- Charles Fabry Laboratory University of Paris-Saclay, Institute of Optics Graduate School, CNRS, Palaiseau Cedex, France
- Nanomaterials and Nanotechnology Research Center (CINN-CSIC), University of Oviedo (UO), El Entrego, Spain
| | - Tommaso Comparin
- Laboratory of Physics, University of Lyon, Ens de Lyon, CNRS, Lyon, France
| | - Fabio Mezzacapo
- Laboratory of Physics, University of Lyon, Ens de Lyon, CNRS, Lyon, France
| | - Tommaso Roscilde
- Laboratory of Physics, University of Lyon, Ens de Lyon, CNRS, Lyon, France
| | - Thierry Lahaye
- Charles Fabry Laboratory University of Paris-Saclay, Institute of Optics Graduate School, CNRS, Palaiseau Cedex, France
| | - Norman Y Yao
- Department of Physics, Harvard University, Cambridge, MA, USA
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Antoine Browaeys
- Charles Fabry Laboratory University of Paris-Saclay, Institute of Optics Graduate School, CNRS, Palaiseau Cedex, France
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Chu Y, Li X, Cai J. Strong Quantum Metrological Limit from Many-Body Physics. PHYSICAL REVIEW LETTERS 2023; 130:170801. [PMID: 37172232 DOI: 10.1103/physrevlett.130.170801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/05/2023] [Accepted: 04/03/2023] [Indexed: 05/14/2023]
Abstract
Surpassing the standard quantum limit and even reaching the Heisenberg limit using quantum entanglement, represents the Holy Grail of quantum metrology. However, quantum entanglement is a valuable resource that does not come without a price. The exceptional time overhead for the preparation of large-scale entangled states raises disconcerting concerns about whether the Heisenberg limit is fundamentally achievable. Here, we find a universal speed limit set by the Lieb-Robinson light cone for the quantum Fisher information growth to characterize the metrological potential of quantum resource states during their preparation. Our main result establishes a strong precision limit of quantum metrology accounting for the complexity of many-body quantum resource state preparation and reveals a fundamental constraint for reaching the Heisenberg limit in a generic many-body lattice system with bounded one-site energy. It enables us to identify the essential features of quantum many-body systems that are crucial for achieving the quantum advantage of quantum metrology, and brings an interesting connection between many-body quantum dynamics and quantum metrology.
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Affiliation(s)
- Yaoming Chu
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Hubei Key Laboratory of Gravitation and Quantum Physics, Institute for Quantum Science and Engineering, Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiangbei Li
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Hubei Key Laboratory of Gravitation and Quantum Physics, Institute for Quantum Science and Engineering, Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jianming Cai
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Hubei Key Laboratory of Gravitation and Quantum Physics, Institute for Quantum Science and Engineering, Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
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