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Gutman N, Gorlach A, Tziperman O, Ruimy R, Kaminer I. Universal Control of Symmetric States Using Spin Squeezing. PHYSICAL REVIEW LETTERS 2024; 132:153601. [PMID: 38682988 DOI: 10.1103/physrevlett.132.153601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 03/11/2024] [Indexed: 05/01/2024]
Abstract
The manipulation of quantum many-body systems is a crucial goal in quantum science. Entangled quantum states that are symmetric under qubits permutation are of growing interest. Yet, the creation and control of symmetric states has remained a challenge. Here, we introduce a method to universally control symmetric states, proposing a scheme that relies solely on coherent rotations and spin squeezing. We present protocols for the creation of different symmetric states including Schrödinger's cat and Gottesman-Kitaev-Preskill states. The obtained symmetric states can be transferred to traveling photonic states via spontaneous emission, providing a powerful approach for engineering desired quantum photonic states.
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Affiliation(s)
- Nir Gutman
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Alexey Gorlach
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Offek Tziperman
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ron Ruimy
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ido Kaminer
- Technion-Israel Institute of Technology, Haifa 32000, Israel
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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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Ren ZQ, Lu XL, Xiang ZL. Heisenberg-limited spin squeezing in a hybrid system with silicon-vacancy centers. OPTICS EXPRESS 2024; 32:4013-4026. [PMID: 38297610 DOI: 10.1364/oe.499299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 01/08/2024] [Indexed: 02/02/2024]
Abstract
In this paper, we investigate the spin squeezing in a hybrid quantum system consisting of a Silicon-Vacancy (SiV) center ensemble coupled to a diamond acoustic waveguide via the strain interaction. Two sets of non-overlapping driving fields, each contains two time-dependent microwave fields, are applied to this hybrid system. By modulating these fields, the one-axis twist (OAT) interaction and two-axis two-spin (TATS) interaction can be independently realized. In the latter case the squeezing parameter scales to spin number as ξ R2∼1.61N -0.64 with the consideration of dissipation, which is very close to the Heisenberg limit. Furthermore, this hybrid system allows for the study of spin squeezing generated by the simultaneous presence of OAT and TATS interactions, which reveals sensitivity to the parity of the number of spins Ntot, whether it is even or odd. Our scheme enriches the approach for generating Heisenberg-limited spin squeezing in spin-phonon hybrid systems and offers the possibility for future applications in quantum information processing.
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Yan Z, Ho J, Lu YH, Masson SJ, Asenjo-Garcia A, Stamper-Kurn DM. Superradiant and Subradiant Cavity Scattering by Atom Arrays. PHYSICAL REVIEW LETTERS 2023; 131:253603. [PMID: 38181363 DOI: 10.1103/physrevlett.131.253603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 11/02/2023] [Indexed: 01/07/2024]
Abstract
We realize collective enhancement and suppression of light scattered by an array of tweezer-trapped ^{87}Rb atoms positioned within a strongly coupled Fabry-Pérot optical cavity. We illuminate the array with light directed transverse to the cavity axis, in the low saturation regime, and detect photons scattered into the cavity. For an array with integer-optical-wavelength spacing each atom scatters light into the cavity with nearly identical scattering amplitude, leading to an observed N^{2} scaling of cavity photon number as the atom number increases stepwise from N=1 to N=8. By contrast, for an array with half-integer-wavelength spacing, destructive interference of scattering amplitudes yields a nonmonotonic, subradiant cavity intensity versus N. By analyzing the polarization of light emitted from the cavity, we find that Rayleigh scattering can be collectively enhanced or suppressed with respect to Raman scattering. We observe also that atom-induced shifts and broadenings of the cavity resonance are precisely tuned by varying the atom number and positions. Altogether, tweezer arrays provide exquisite control of atomic cavity QED spanning from the single- to the many-body regime.
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Affiliation(s)
- Zhenjie Yan
- Department of Physics, University of California, Berkeley, California 94720, USA
- Challenge Institute for Quantum Computation, University of California, Berkeley, California 94720, USA
| | - Jacquelyn Ho
- Department of Physics, University of California, Berkeley, California 94720, USA
- Challenge Institute for Quantum Computation, University of California, Berkeley, California 94720, USA
| | - Yue-Hui Lu
- Department of Physics, University of California, Berkeley, California 94720, USA
- Challenge Institute for Quantum Computation, University of California, Berkeley, California 94720, USA
| | - Stuart J Masson
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Ana Asenjo-Garcia
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Dan M Stamper-Kurn
- Department of Physics, University of California, Berkeley, California 94720, USA
- Challenge Institute for Quantum Computation, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Chávez-Carlos J, Lezama TLM, Cortiñas RG, Venkatraman J, Devoret MH, Batista VS, Pérez-Bernal F, Santos LF. Spectral kissing and its dynamical consequences in the squeeze-driven Kerr oscillator. NPJ QUANTUM INFORMATION 2023; 9:76. [PMID: 38665256 PMCID: PMC11041765 DOI: 10.1038/s41534-023-00745-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 07/15/2023] [Indexed: 04/28/2024]
Abstract
Transmon qubits are the predominant element in circuit-based quantum information processing, such as existing quantum computers, due to their controllability and ease of engineering implementation. But more than qubits, transmons are multilevel nonlinear oscillators that can be used to investigate fundamental physics questions. Here, they are explored as simulators of excited state quantum phase transitions (ESQPTs), which are generalizations of quantum phase transitions to excited states. We show that the spectral kissing (coalescence of pairs of energy levels) experimentally observed in the effective Hamiltonian of a driven SNAIL-transmon is an ESQPT precursor. We explore the dynamical consequences of the ESQPT, which include the exponential growth of out-of-time-ordered correlators, followed by periodic revivals, and the slow evolution of the survival probability due to localization. These signatures of ESQPT are within reach for current superconducting circuits platforms and are of interest to experiments with cold atoms and ion traps.
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Affiliation(s)
| | | | - Rodrigo G. Cortiñas
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06520 USA
| | | | - Michel H. Devoret
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06520 USA
| | - Victor S. Batista
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107 USA
| | - Francisco Pérez-Bernal
- Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Física, Matemáticas y Computación, Universidad de Huelva, Huelva, 21071 Spain
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
| | - Lea F. Santos
- Department of Physics, University of Connecticut, Storrs, CT 06269 USA
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