1
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Montenegro V, Jones GS, Bose S, Bayat A. Sequential Measurements for Quantum-Enhanced Magnetometry in Spin Chain Probes. PHYSICAL REVIEW LETTERS 2022; 129:120503. [PMID: 36179207 DOI: 10.1103/physrevlett.129.120503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Quantum sensors outperform their classical counterparts in their estimation precision, given the same amount of resources. So far, quantum-enhanced sensitivity has been achieved by exploiting the superposition principle. This enhancement has been obtained for particular forms of entangled states, adaptive measurement basis change, critical many-body systems, and steady state of periodically driven systems. Here, we introduce a different approach to obtain quantum-enhanced sensitivity in a many-body probe through utilizing the nature of quantum measurement and its subsequent wave function collapse without demanding prior entanglement. Our protocol consists of a sequence of local measurements, without reinitialization, performed regularly during the evolution of a many-body probe. As the number of sequences increases, the sensing precision is enhanced beyond the standard limit, reaching the Heisenberg bound asymptotically. The benefits of the protocol are multifold as it uses a product initial state and avoids complex initialization (e.g., prior entangled states or critical ground states) and allows for remote quantum sensing.
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Affiliation(s)
- Victor Montenegro
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610051, China
| | - Gareth Siôn Jones
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Sougato Bose
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Abolfazl Bayat
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610051, China
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2
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Integrable quantum many-body sensors for AC field sensing. Sci Rep 2022; 12:14760. [PMID: 36042211 PMCID: PMC9427993 DOI: 10.1038/s41598-022-17381-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 07/25/2022] [Indexed: 11/08/2022] Open
Abstract
Quantum sensing is inevitably an elegant example of the supremacy of quantum technologies over their classical counterparts. One of the desired endeavors of quantum metrology is AC field sensing. Here, by means of analytical and numerical analysis, we show that integrable many-body systems can be exploited efficiently for detecting the amplitude of an AC field. Unlike the conventional strategies in using the ground states in critical many-body probes for parameter estimation, we only consider partial access to a subsystem. Due to the periodicity of the dynamics, any local block of the system saturates to a steady state which allows achieving sensing precision well beyond the classical limit, almost reaching the Heisenberg bound. We associate the enhanced quantum precision to closing of the Floquet gap, resembling the features of quantum sensing in the ground state of critical systems. We show that the proposed protocol can also be realized in near-term quantum simulators, e.g. ion-traps, with a limited number of qubits. We show that in such systems a simple block magnetization measurement and a Bayesian inference estimator can achieve very high precision AC field sensing.
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3
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Chu Y, Liu Y, Liu H, Cai J. Quantum Sensing with a Single-Qubit Pseudo-Hermitian System. PHYSICAL REVIEW LETTERS 2020; 124:020501. [PMID: 32004038 DOI: 10.1103/physrevlett.124.020501] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Indexed: 06/10/2023]
Abstract
Quantum sensing exploits the fundamental features of a quantum system to achieve highly efficient measurement of physical quantities. Here, we propose a strategy to realize a single-qubit pseudo-Hermitian sensor from a dilated two-qubit Hermitian system. The pseudo-Hermitian sensor exhibits divergent susceptibility in a dynamical evolution that does not necessarily involve an exceptional point. We demonstrate its potential advantages to overcome noises that cannot be averaged out by repetitive measurements. The proposal is feasible with the state-of-art experimental capability in a variety of qubit systems, and represents a step towards the application of non-Hermitian physics in quantum sensing.
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Affiliation(s)
- Yaoming Chu
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yu Liu
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Haibin Liu
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jianming Cai
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Huazhong University of Science and Technology, Wuhan 430074, China
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4
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Takahashi H, Kassa E, Christoforou C, Keller M. Strong Coupling of a Single Ion to an Optical Cavity. PHYSICAL REVIEW LETTERS 2020; 124:013602. [PMID: 31976684 DOI: 10.1103/physrevlett.124.013602] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Indexed: 06/10/2023]
Abstract
Strong coupling between an atom and an electromagnetic resonator is an important condition in cavity quantum electrodynamics. While strong coupling in various physical systems has been achieved so far, it remained elusive for single atomic ions. Here, we achieve a coupling strength of 2π×(12.3±0.1) MHz between a single ^{40}Ca^{+} ion and an optical cavity, exceeding both atomic and cavity decay rates which are 2π×11.5 and 2π×(4.1±0.1) MHz, respectively. We use cavity assisted Raman spectroscopy to precisely characterize the ion-cavity coupling strength and observe a spectrum featuring the normal mode splitting in the cavity transmission due to the ion-cavity interaction. Our work paves the way towards new applications of cavity quantum electrodynamics utilizing single trapped ions in the strong coupling regime for quantum optics and quantum technologies.
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Affiliation(s)
- Hiroki Takahashi
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - Ezra Kassa
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - Costas Christoforou
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - Matthias Keller
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
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5
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Stark A, Aharon N, Huck A, El-Ella HAR, Retzker A, Jelezko F, Andersen UL. Clock transition by continuous dynamical decoupling of a three-level system. Sci Rep 2018; 8:14807. [PMID: 30287884 PMCID: PMC6172288 DOI: 10.1038/s41598-018-31984-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/28/2018] [Indexed: 11/09/2022] Open
Abstract
We present a novel continuous dynamical decoupling scheme for the construction of a robust qubit in a three-level system. By means of a clock transition adjustment, we first show how robustness to environmental noise is achieved, while eliminating drive-noise, to first-order. We demonstrate this scheme with the spin sub-levels of the NV-centre's electronic ground state. By applying drive fields with moderate Rabi frequencies, the drive noise is eliminated and an improvement of 2 orders of magnitude in the coherence time is obtained compared to the pure dephasing time. We then show how the clock transition adjustment can be tuned to eliminate also the second-order effect of the environmental noise with moderate drive fields. A further detailed theoretical investigation suggests an additional improvement of more than 1 order of magnitude in the coherence time which is supported by simulations. Hence, our scheme predicts that the coherence time may be prolonged towards the lifetime-limit using a relatively simple experimental setup.
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Affiliation(s)
- Alexander Stark
- Center for Macroscopic Quantum States (bigQ), Department of Physics, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark.
- Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, Ulm, 89081, Germany.
| | - Nati Aharon
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Alexander Huck
- Center for Macroscopic Quantum States (bigQ), Department of Physics, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark
| | - Haitham A R El-Ella
- Center for Macroscopic Quantum States (bigQ), Department of Physics, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark
| | - Alex Retzker
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Fedor Jelezko
- Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, Ulm, 89081, Germany
- Center for Integrated Quantum Science and Technology (IQst), Ulm University, Ulm, 89081, Germany
| | - Ulrik L Andersen
- Center for Macroscopic Quantum States (bigQ), Department of Physics, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark
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Jachymski K, Wasak T, Idziaszek Z, Julienne PS, Negretti A, Calarco T. Single-Atom Transistor as a Precise Magnetic Field Sensor. PHYSICAL REVIEW LETTERS 2018; 120:013401. [PMID: 29350943 DOI: 10.1103/physrevlett.120.013401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/27/2017] [Indexed: 06/07/2023]
Abstract
Feshbach resonances, which allow for tuning the interactions of ultracold atoms with an external magnetic field, have been widely used to control the properties of quantum gases. We propose a scheme for using scattering resonances as a probe for external fields, showing that by carefully tuning the parameters it is possible to reach a 10^{-5} G (or nT) level of precision with a single pair of atoms. We show that, for our collisional setup, it is possible to saturate the quantum precision bound with a simple measurement protocol.
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Affiliation(s)
- Krzysztof Jachymski
- Institute for Theoretical Physics III and Center for Integrated Quantum Science and Technologies (IQST), University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Tomasz Wasak
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Zbigniew Idziaszek
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Paul S Julienne
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - Antonio Negretti
- Zentrum für Optische Quantentechnologien and The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Tommaso Calarco
- Institute for Complex Quantum Systems and Center for Integrated Quantum Science and Technologies (IQST), Universität Ulm, 89069 Ulm, Germany
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7
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Trypogeorgos D, Valdés-Curiel A, Lundblad N, Spielman IB. Synthetic clock transitions via continuous dynamical decoupling. PHYSICAL REVIEW. A 2018; 97:013407. [PMID: 30997439 PMCID: PMC6463877 DOI: 10.1103/physreva.97.013407] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Decoherence of quantum systems due to uncontrolled fluctuations of the environment presents fundamental obstacles in quantum science. Clock transitions which are insensitive to such fluctuations are used to improve coherence, however, they are not present in all systems or for arbitrary system parameters. Here we create a trio of synthetic clock transitions using continuous dynamical decoupling in a spin-1 Bose-Einstein condensate in which we observe a reduction of sensitivity to magnetic-field noise of up to four orders of magnitude; this work complements the parallel work by Anderson et al.. In addition, using a concatenated scheme, we demonstrate suppression of sensitivity to fluctuations in our control fields. These field-insensitive states represent an ideal foundation for the next generation of cold-atom experiments focused on fragile many-body phases relevant to quantum magnetism, artificial gauge fields, and topological matter.
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Affiliation(s)
- D. Trypogeorgos
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - A. Valdés-Curiel
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - N. Lundblad
- Department of Physics and Astronomy, Bates College, Lewiston, Maine 04240, USA
| | - I. B. Spielman
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
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8
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Stark A, Aharon N, Unden T, Louzon D, Huck A, Retzker A, Andersen UL, Jelezko F. Narrow-bandwidth sensing of high-frequency fields with continuous dynamical decoupling. Nat Commun 2017; 8:1105. [PMID: 29051547 PMCID: PMC5648921 DOI: 10.1038/s41467-017-01159-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 08/22/2017] [Indexed: 11/09/2022] Open
Abstract
State-of-the-art methods for sensing weak AC fields are only efficient in the low frequency domain (<10 MHz). The inefficiency of sensing high-frequency signals is due to the lack of ability to use dynamical decoupling. In this paper we show that dynamical decoupling can be incorporated into high-frequency sensing schemes and by this we demonstrate that the high sensitivity achieved for low frequency can be extended to the whole spectrum. While our scheme is general and suitable to a variety of atomic and solid-state systems, we experimentally demonstrate it with the nitrogen-vacancy center in diamond. For a diamond with natural abundance of 13C, we achieve coherence times up to 1.43 ms resulting in a smallest detectable magnetic field strength of 4 nT at 1.6 GHz. Attributed to the inherent nature of our scheme, we observe an additional increase in coherence time due to the signal itself.
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Affiliation(s)
- Alexander Stark
- Department of Physics, Technical University of Denmark, Fysikvej, Kongens Lyngby, 2800, Denmark.
- Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, Ulm, 89081, Germany.
| | - Nati Aharon
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Thomas Unden
- Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, Ulm, 89081, Germany
| | - Daniel Louzon
- Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, Ulm, 89081, Germany
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Alexander Huck
- Department of Physics, Technical University of Denmark, Fysikvej, Kongens Lyngby, 2800, Denmark
| | - Alex Retzker
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Ulrik L Andersen
- Department of Physics, Technical University of Denmark, Fysikvej, Kongens Lyngby, 2800, Denmark
| | - Fedor Jelezko
- Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, Ulm, 89081, Germany.
- Center for Integrated Quantum Science and Technology (IQst), Ulm University, Ulm, 89081, Germany.
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9
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Lekitsch B, Weidt S, Fowler AG, Mølmer K, Devitt SJ, Wunderlich C, Hensinger WK. Blueprint for a microwave trapped ion quantum computer. SCIENCE ADVANCES 2017; 3:e1601540. [PMID: 28164154 PMCID: PMC5287699 DOI: 10.1126/sciadv.1601540] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 12/15/2016] [Indexed: 06/02/2023]
Abstract
The availability of a universal quantum computer may have a fundamental impact on a vast number of research fields and on society as a whole. An increasingly large scientific and industrial community is working toward the realization of such a device. An arbitrarily large quantum computer may best be constructed using a modular approach. We present a blueprint for a trapped ion-based scalable quantum computer module, making it possible to create a scalable quantum computer architecture based on long-wavelength radiation quantum gates. The modules control all operations as stand-alone units, are constructed using silicon microfabrication techniques, and are within reach of current technology. To perform the required quantum computations, the modules make use of long-wavelength radiation-based quantum gate technology. To scale this microwave quantum computer architecture to a large size, we present a fully scalable design that makes use of ion transport between different modules, thereby allowing arbitrarily many modules to be connected to construct a large-scale device. A high error-threshold surface error correction code can be implemented in the proposed architecture to execute fault-tolerant operations. With appropriate adjustments, the proposed modules are also suitable for alternative trapped ion quantum computer architectures, such as schemes using photonic interconnects.
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Affiliation(s)
- Bjoern Lekitsch
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K
| | - Sebastian Weidt
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K
| | | | - Klaus Mølmer
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Simon J. Devitt
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 315-0198, Japan
| | - Christof Wunderlich
- Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany
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Weidt S, Randall J, Webster SC, Lake K, Webb AE, Cohen I, Navickas T, Lekitsch B, Retzker A, Hensinger WK. Trapped-Ion Quantum Logic with Global Radiation Fields. PHYSICAL REVIEW LETTERS 2016; 117:220501. [PMID: 27925715 DOI: 10.1103/physrevlett.117.220501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Indexed: 06/06/2023]
Abstract
Trapped ions are a promising tool for building a large-scale quantum computer. However, the number of required radiation fields for the realization of quantum gates in any proposed ion-based architecture scales with the number of ions within the quantum computer, posing a major obstacle when imagining a device with millions of ions. Here, we present a fundamentally different approach for trapped-ion quantum computing where this detrimental scaling vanishes. The method is based on individually controlled voltages applied to each logic gate location to facilitate the actual gate operation analogous to a traditional transistor architecture within a classical computer processor. To demonstrate the key principle of this approach we implement a versatile quantum gate method based on long-wavelength radiation and use this method to generate a maximally entangled state of two quantum engineered clock qubits with fidelity 0.985(12). This quantum gate also constitutes a simple-to-implement tool for quantum metrology, sensing, and simulation.
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Affiliation(s)
- S Weidt
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - J Randall
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - S C Webster
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - K Lake
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - A E Webb
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - I Cohen
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Givat Ram, Israel
| | - T Navickas
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - B Lekitsch
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - A Retzker
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Givat Ram, Israel
| | - W K Hensinger
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
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