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In this work we investigate how to quantify the coherence of quantum measurements. First, we establish a resource theoretical framework to address the coherence of measurement and show that any statistical distance can be adopted to define…

Quantum Physics · Physics 2020-08-11 Kyunghyun Baek , Adel Sohbi , Jaehak Lee , Jaewan Kim , Hyunchul Nha

The coherent states that describe the classical motion of a mechanical oscillator do not have well-defined energy, but are rather quantum superpositions of equally-spaced energy eigenstates. Revealing this quantized structure is only…

Bounds of the minimum evolution time between two distinguishable states of a system can help to assess the maximal speed of quantum computers and communication channels. We study the quantum speed limit time of a composite quantum states in…

Quantum Physics · Physics 2014-09-16 Ying-Jie Zhang , Wei Han , Yun-Jie Xia , Ke-Xia Jiang , Jun-Peng Cao , Heng Fan

Optomechanical detectors have reached the standard quantum limit in position and force sensing where measurement backaction noise starts to be the limiting factor for the sensitivity. A strategy to circumvent measurement backaction, and…

Quantum Physics · Physics 2014-06-11 Maximilian H. Wimmer , Daniel Steinmeyer , Klemens Hammerer , Michèle Heurs

It is known that the overlap of two energy eigenstates in a decaying quantum system is bounded from above by a function of the energy detuning and the individual decay rates. This is usually traced back to the positive definiteness of an…

Quantum Physics · Physics 2019-12-23 Jan Wiersig

In this paper we introduce a measure of genuine quantum incompatibility in the estimation task of multiple parameters, that has a geometric character and is backed by a clear operational interpretation. This measure is then applied to some…

Quantum Physics · Physics 2021-06-22 Federico Belliardo , Vittorio Giovannetti

We propose to detect quantum entanglement by a condition of local measurments. We find that this condition can detect efficiently the pure entangled states for both discrete and continuous variable systems. It does not depend on…

Quantum Physics · Physics 2015-05-30 Qing Xie , X. -X. Wu , X. -M. Ding , W. -L. Yang , R. -H. Yue , H. Fan

We investigate the entanglement structure of a bipartite quantum system through the lens of quantum thermodynamics in the absence of conformal symmetry. Specifically, we consider the long-range Kitaev model, where the pairing interaction…

Strongly Correlated Electrons · Physics 2025-08-04 Akash Mitra , Shashi C. L. Srivastava

We investigate if physical laws can impose limit on computational time and speed of a quantum computer built from elementary particles. We show that the product of the speed and the running time of a quantum computer is limited by the type…

Quantum Physics · Physics 2015-06-26 A. K. Pati , S. R. Jain , A. Mitra , R. Ramanna

Quantum information technologies require careful control for generating and preserving a desired target quantum state. The biggest practical obstacle is, of course, decoherence. Therefore, the reachability analysis, which in our scenario…

Quantum Physics · Physics 2019-05-30 Kohei Kobayashi , Naoki Yamamoto

Precise definitions for different degrees of controllability for quantum systems are given, and necessary and sufficient conditions are discussed. The results are applied to determine the degree of controllability for various atomic systems…

Quantum Physics · Physics 2009-11-07 S. G. Schirmer , J. V. Leahy , A. I. Solomon

Several optomechanics experiments are now entering the highly sought nonlinear regime where optomechanical interactions are large even for low light levels. Within this regime, new quantum phenomena and improved performance may be achieved,…

Quantum Physics · Physics 2023-08-04 Jack Clarke , Pascal Neveu , Kiran E. Khosla , Ewold Verhagen , Michael R. Vanner

The complex Hilbert space of standard quantum mechanics may be treated as a real Hilbert space. The pure states of the complex theory become mixed states in the real formulation. It is then possible to generalize standard quantum mechanics,…

Quantum Physics · Physics 2007-05-23 Jan Myrheim

Quantum technologies exploit entanglement to enhance various tasks beyond their classical limits including computation, communication and measurements. Quantum metrology aims to increase the precision of a measured quantity that is…

Quantum Physics · Physics 2020-08-25 Bálint Koczor , Suguru Endo , Tyson Jones , Yuichiro Matsuzaki , Simon C. Benjamin

Relativity and quantum mechanics are generalized by considering a finite limit for the smallest measurable distance. The value a of this quantum of length is unknown, but it is a universal constant, like c and h. It depends on the total…

General Physics · Physics 2011-08-25 A. Meessen

The decay of an unstable system is usually described by an exponential law. Quantum mechanics predicts strong deviations of the survival probability from the exponential: indeed, the decay is initially quadratic, while at very large times…

We analyze a cavity optomechanical setup, in which position of an oscillator modulates optical loss. We show that in such setup quantum limited position measurements can be performed if the external cavity coupling rate matches the optical…

Quantum Physics · Physics 2019-07-31 A. K. Tagantsev , S. A. Fedorov

In the field of cavity optomechanics, proposals for quantum nondemolition (QND) measurements of phonon number provide a promising avenue by which one can study the quantum nature of nanoscale mechanical resonators. Here, we investigate…

Quantum Physics · Physics 2018-10-10 B. D. Hauer , A. Metelmann , J. P. Davis

Quantum mechanics imposes a lower bound on the time required for a quantum system to reach certain given targets. In this paper, from a geometric perspective, we introduce a new quantum speed limit (QSL) based on the Bloch angle and derive…

Quantum Physics · Physics 2025-07-02 Qianyi Wang , Ben Wang , Jun Wang , Lijian Zhang

Quantum thermodynamics is a research field that aims at fleshing out the ultimate limits of thermodynamic processes in the deep quantum regime. A complete picture of quantum thermodynamics allows for catalysts, i.e., systems facilitating…

Quantum Physics · Physics 2015-09-02 Nelly Huei Ying Ng , Laura Mančinska , Cristina Cirstoiu , Jens Eisert , Stephanie Wehner