1
|
Innocenti L, Lachman L, Filip R. Coherence-Based Operational Nonclassicality Criteria. PHYSICAL REVIEW LETTERS 2023; 131:160201. [PMID: 37925708 DOI: 10.1103/physrevlett.131.160201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 03/15/2023] [Accepted: 09/13/2023] [Indexed: 11/07/2023]
Abstract
The nonclassicality of quantum states is a fundamental resource for quantum technologies and quantum information tasks, in general. In particular, a pivotal aspect of quantum states lies in their coherence properties, encoded in the nondiagonal terms of their density matrix in the Fock-state bosonic basis. We present operational criteria to detect the nonclassicality of individual quantum coherences that use only data obtainable in experimentally realistic scenarios. We analyze and compare the robustness of the nonclassical coherence aspects when the states pass through lossy and noisy channels. The criteria can be immediately applied to experiments with light, atoms, solid-state system, and mechanical oscillators, thus providing a toolbox allowing practical experiments to more easily detect the nonclassicality of generated states.
Collapse
Affiliation(s)
- Luca Innocenti
- Department of Optics, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic
- Università degli Studi di Palermo, Dipartimento di Fisica e Chimica-Emilio Segrè, via Archirafi 36, I-90123 Palermo, Italy
| | - Lukáš Lachman
- Department of Optics, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic
| | - Radim Filip
- Department of Optics, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic
| |
Collapse
|
2
|
Wang H, Chen Z, Fu Z, Shi Y, Zhang X, Zhao C, Jin S, Jing J. Phase-insensitive amplifier gain estimation at Cramér-Rao bound for two-mode squeezed state of light. OPTICS EXPRESS 2023; 31:13552-13565. [PMID: 37157240 DOI: 10.1364/oe.483770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Phase-insensitive amplifiers (PIAs), as a class of important quantum devices, have found significant applications in the subtle manipulation of multiple quantum correlation and multipartite quantum entanglement. Gain is a very important parameter for quantifying the performance of a PIA. Its absolute value can be defined as the ratio of the output light beam power to the input light beam power, while its estimation precision has not been extensively investigated yet. Therefore, in this work, we theoretically study the estimation precision from the vacuum two-mode squeezed state (TMSS), the estimation precision of the coherent state, and the bright TMSS scenario, which has the following two advantages: it has more probe photons than the vacuum TMSS and higher estimation precision than the coherent state. The advantage in terms of estimation precision of the bright TMSS compared with the coherent state is researched. We first simulate the effect of noise from another PIA with gain M on the estimation precision of the bright TMSS, and we find that a scheme in which the PIA is placed in the auxiliary light beam path is more robust than two other schemes. Then, a fictitious beam splitter with transmission T is used to simulate the noise effects of propagation loss and imperfect detection, and the results show that a scheme in which the fictitious beam splitter is placed before the original PIA in the probe light beam path is the most robust. Finally, optimal intensity difference measurement is confirmed to be an accessible experimental technique to saturate estimation precision of the bright TMSS. Therefore, our present study opens a new avenue for quantum metrology based on PIAs.
Collapse
|
3
|
Woodworth TS, Hermann-Avigliano C, Chan KWC, Marino AM. Transmission estimation at the quantum Cramér-Rao bound with macroscopic quantum light. EPJ QUANTUM TECHNOLOGY 2022; 9:38. [PMID: 36573927 PMCID: PMC9780138 DOI: 10.1140/epjqt/s40507-022-00154-x] [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: 09/10/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
The field of quantum metrology seeks to apply quantum techniques and/or resources to classical sensing approaches with the goal of enhancing the precision in the estimation of a parameter beyond what can be achieved with classical resources. Theoretically, the fundamental minimum uncertainty in the estimation of a parameter for a given probing state is bounded by the quantum Cramér-Rao bound. From a practical perspective, it is necessary to find physical measurements that can saturate this fundamental limit and to show experimentally that it is possible to perform measurements with the required precision to do so. Here we perform experiments that saturate the quantum Cramér-Rao bound for transmission estimation over a wide range of transmissions when probing the system under study with a continuous wave bright two-mode squeezed state. To properly take into account the imperfections in the generation of the quantum state, we extend our previous theoretical results to incorporate the measured properties of the generated quantum state. For our largest transmission level of 84%, we show a 62% reduction over the optimal classical protocol in the variance in transmission estimation when probing with a bright two-mode squeezed state with -8 dB of intensity-difference squeezing. Given that transmission estimation is an integral part of many sensing protocols, such as plasmonic sensing, spectroscopy, calibration of the quantum efficiency of detectors, etc., the results presented promise to have a significant impact on a number of applications in various fields of research.
Collapse
Affiliation(s)
- Timothy S. Woodworth
- 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
| | - Carla Hermann-Avigliano
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
- ANID – Millennium Science Initiative Program – Millennium Institute for Research in Optics (MIRO), Santiago, Chile
| | | | - Alberto M. Marino
- 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
- Quantum Information Science Section, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37381 USA
- Quantum Science Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37381 USA
| |
Collapse
|
4
|
Ferrari G, Lami L, Theurer T, Plenio MB. Asymptotic State Transformations of Continuous Variable Resources. COMMUNICATIONS IN MATHEMATICAL PHYSICS 2022; 398:291-351. [PMID: 36751403 PMCID: PMC9898434 DOI: 10.1007/s00220-022-04523-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 08/30/2022] [Indexed: 06/18/2023]
Abstract
We study asymptotic state transformations in continuous variable quantum resource theories. In particular, we prove that monotones displaying lower semicontinuity and strong superadditivity can be used to bound asymptotic transformation rates in these settings. This removes the need for asymptotic continuity, which cannot be defined in the traditional sense for infinite-dimensional systems. We consider three applications, to the resource theories of (I) optical nonclassicality, (II) entanglement, and (III) quantum thermodynamics. In cases (II) and (III), the employed monotones are the (infinite-dimensional) squashed entanglement and the free energy, respectively. For case (I), we consider the measured relative entropy of nonclassicality and prove it to be lower semicontinuous and strongly superadditive. One of our main technical contributions, and a key tool to establish these results, is a handy variational expression for the measured relative entropy of nonclassicality. Our technique then yields computable upper bounds on asymptotic transformation rates, including those achievable under linear optical elements. We also prove a number of results which guarantee that the measured relative entropy of nonclassicality is bounded on any physically meaningful state and easily computable for some classes of states of interest, e.g., Fock diagonal states. We conclude by applying our findings to the problem of cat state manipulation and noisy Fock state purification.
Collapse
Affiliation(s)
- Giovanni Ferrari
- Dipartimento di Fisica e Astronomia Galileo Galilei, Università degli studi di Padova, Via Marzolo 8, 35131 Padua, Italy
- Institut für Theoretische Physik und IQST, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Ludovico Lami
- Institut für Theoretische Physik und IQST, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Thomas Theurer
- Institut für Theoretische Physik und IQST, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Martin B. Plenio
- Institut für Theoretische Physik und IQST, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| |
Collapse
|
5
|
Wei CP. Nonclassicality and entanglement as a quantifiable measure for phase estimation. OPTICS EXPRESS 2022; 30:40174-40187. [PMID: 36298954 DOI: 10.1364/oe.469423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Abstract
We establish an approach to measure the nonclassicality of a two-mode quantum state by extending the method of quantifying nonclassicality for a single-mode quantum state. We then discuss the nonclassicality and entanglement properties of several different quantum states, and determine the optimal phase estimation for entangled coherent states (ecs) in the form of nonclassicality and concurrence. Accordingly, a new interferometer (linear and nonlinear) scheme is proposed by modifying a traditional interferometer. Specially, we specify a new normal ordering form of the evolution operator of nonlinear interferometer (NI) using the techniques of integration within an ordered product of operators (IWOP), and obtain the parity signal based on representation of the coherent state. By inputting several common quantum states, we further study the phase sensitivity of the linear interferometer (LI) and NI with parity detection, and perform a detailed comparison among the different input states schemes. Furthermore, we quantitatively investigated the effect of nonclassicality and entanglement on the phase sensitivity of two interferometers. These results show that nonclassicality or entanglement is very crucial but not a necessary condition for improving the phase sensitivity of interferometers.
Collapse
|
6
|
Patil YSS, Yu J, Frazier S, Wang Y, Johnson K, Fox J, Reichel J, Harris JGE. Measuring High-Order Phonon Correlations in an Optomechanical Resonator. PHYSICAL REVIEW LETTERS 2022; 128:183601. [PMID: 35594119 DOI: 10.1103/physrevlett.128.183601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/18/2022] [Indexed: 06/15/2023]
Abstract
We use single photon detectors to probe the motional state of a superfluid ^{4}He resonator of mass ∼1 ng. The arrival times of Stokes and anti-Stokes photons (scattered by the resonator's acoustic mode) are used to measure the resonator's phonon coherences up to the fourth order. By postselecting on photon detection events, we also measure coherences in the resonator when ≤3 phonons have been added or subtracted. These measurements are found to be consistent with predictions that assume the acoustic mode to be in thermal equilibrium with a bath through a Markovian coupling.
Collapse
Affiliation(s)
- Y S S Patil
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - J Yu
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - S Frazier
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Y Wang
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - K Johnson
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - J Fox
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - J Reichel
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France 24 rue Lhomond, 75005 Paris, France
| | - J G E Harris
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
| |
Collapse
|
7
|
Tan KC, Narasimhachar V, Regula B. Fisher Information Universally Identifies Quantum Resources. PHYSICAL REVIEW LETTERS 2021; 127:200402. [PMID: 34860070 DOI: 10.1103/physrevlett.127.200402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 07/31/2021] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
We show that both the classical as well as the quantum definitions of the Fisher information faithfully identify resourceful quantum states in general quantum resource theories, in the sense that they can always distinguish between states with and without a given resource. This shows that all quantum resources confer an advantage in metrology, and establishes the Fisher information as a universal tool to probe the resourcefulness of quantum states. We provide bounds on the extent of this advantage, as well as a simple criterion to test whether different resources are useful for the estimation of unitarily encoded parameters. Finally, we extend the results to show that the Fisher information is also able to identify the dynamical resourcefulness of quantum operations.
Collapse
Affiliation(s)
- Kok Chuan Tan
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Republic of Singapore
| | - Varun Narasimhachar
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Republic of Singapore
| | - Bartosz Regula
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Republic of Singapore
| |
Collapse
|
8
|
Abstract
The extraordinary sensitivity of plasmonic sensors is well-known in the optics and photonics community. These sensors exploit simultaneously the enhancement and the localization of electromagnetic fields close to the interface between a metal and a dielectric. This enables, for example, the design of integrated biochemical sensors at scales far below the diffraction limit. Despite their practical realization and successful commercialization, the sensitivity and associated precision of plasmonic sensors are starting to reach their fundamental classical limit given by quantum fluctuations of light-known as the shot-noise limit. To improve the sensing performance of these sensors beyond the classical limit, quantum resources are increasingly being employed. This area of research has become known as "quantum plasmonic sensing", and it has experienced substantial activity in recent years for applications in chemical and biological sensing. This review aims to cover both plasmonic and quantum techniques for sensing, and it shows how they have been merged to enhance the performance of plasmonic sensors beyond traditional methods. We discuss the general framework developed for quantum plasmonic sensing in recent years, covering the basic theory behind the advancements made, and describe the important works that made these advancements. We also describe several key works in detail, highlighting their motivation, the working principles behind them, and their future impact. The intention of the review is to set a foundation for a burgeoning field of research that is currently being explored out of intellectual curiosity and for a wide range of practical applications in biochemistry, medicine, and pharmaceutical research.
Collapse
Affiliation(s)
- Changhyoup Lee
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.,Quantum Universe Center, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Benjamin Lawrie
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Raphael Pooser
- Quantum Information Science Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Kwang-Geol Lee
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - Carsten Rockstuhl
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021Karlsruhe, Germany.,Max Planck School of Photonics, 07745 Jena, Germany
| | - Mark Tame
- Department of Physics, Stellenbosch University, Stellenbosch 7602, South Africa
| |
Collapse
|
9
|
|
10
|
|
11
|
Tan KC, Choi S, Jeong H. Negativity of Quasiprobability Distributions as a Measure of Nonclassicality. PHYSICAL REVIEW LETTERS 2020; 124:110404. [PMID: 32242693 DOI: 10.1103/physrevlett.124.110404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 02/26/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate that the negative volume of any s-parametrized quasiprobability, including the Glauber-Sudashan P function, can be consistently defined and forms a continuous hierarchy of nonclassicality measures that are linear optical monotones. These measures belong to an operational resource theory of nonclassicality based on linear optical operations. The negativity of the Glauber-Sudashan P function, in particular, can be shown to have an operational interpretation as the robustness of nonclassicality. We then introduce an approximate linear optical monotone, and we show that this nonclassicality quantifier is computable and is able to identify the nonclassicality of nearly all nonclassical states.
Collapse
Affiliation(s)
- Kok Chuan Tan
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639673, Republic of Singapore
| | - Seongjeon Choi
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Hyunseok Jeong
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| |
Collapse
|