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We consider the problem of designing a measurement to minimize the probability of a detection error when distinguishing between a collection of possibly non-orthogonal mixed quantum states. We show that if the quantum state ensemble…

Quantum Physics · Physics 2009-11-10 Yonina C. Eldar

We propose a protocol to test whether the postulate of a measurement acting as an instantaneous projection onto an eigenstate of the measurement apparatus is compatible with physical reality. This approach is solely based on repeated…

Quantum Physics · Physics 2025-06-26 Leonard Werner Pingen , Mattia Moroder , Sebastian Paeckel

We propose simple schemes that can perfectly identify projective measurement apparatus secretly chosen from a finite set. Entanglements are used in these schemes both to make possible the perfect identification and to improve the efficiency…

Quantum Physics · Physics 2007-05-23 Zhengfeng Ji , Yuan Feng , Runyao Duan , Mingsheng Ying

We propose a quantum tomography scheme for pure qudit systems which adopts random base measurements and generative learning methods, along with a built-in fidelity estimation approach to assess the reliability of the tomographic states. We…

Quantum Physics · Physics 2020-03-25 Jun Wang , Zhao-Yu Han , Song-Bo Wang , Zeyang Li , Liang-Zhu Mu , Heng Fan , Lei Wang

Quantum illumination is a technique for detecting the presence of a target in a noisy environment by means of a quantum probe. We prove that the two-mode squeezed vacuum state is the optimal probe for quantum illumination in the scenario of…

Quantum Physics · Physics 2018-07-11 Giacomo De Palma , Johannes Borregaard

We report an alternative scheme for implementing generalized quantum measurements that does not require the usage of auxiliary system. Our method utilizes solely: (a) classical randomness and post-processing, (b) projective measurements on…

Quantum Physics · Physics 2019-08-30 Michał Oszmaniec , Filip B. Maciejewski , Zbigniew Puchała

The onset of the era of fully-programmable error-corrected quantum computers will be marked by major breakthroughs in all areas of science and engineering. These devices promise to have significant technological and societal impact, notable…

Quantum Physics · Physics 2019-11-22 Kishor Bharti , Maharshi Ray , Antonios Varvitsiotis , Adán Cabello , Leong-Chuan Kwek

We describe a quantum state tomography scheme which is applicable to a system described in a Hilbert space of arbitrary finite dimensionality and is constructed from sequences of two measurements. The scheme consists of measuring the…

Quantum Physics · Physics 2015-06-04 Amir Kalev , Pier A. Mello

Universal quantum computation using optical coherent states is studied. A teleportation scheme for a coherent-state qubit is developed and applied to gate operations. This scheme is shown to be robust to detection inefficiency.

Quantum Physics · Physics 2009-11-07 H. Jeong , M. S. Kim

We propose a scalable approach to building cluster states of matter qubits using coherent states of light. Recent work on the subject relies on the use of single photonic qubits in the measurement process. These schemes have a low initial…

Quantum Physics · Physics 2009-11-13 Sebastien G. R. Louis , Kae Nemoto , W. J. Munro , T. P. Spiller

We experimentally demonstrate a new measurement scheme for the discrimination of two coherent states. The measurement scheme is based on a displacement operation followed by a photon number resolving detector, and we show that it…

Quantum Physics · Physics 2010-10-12 Christoffer Wittmann , Ulrik L. Andersen , Masahiro Takeoka , Denis Sych , Gerd Leuchs

We describe and realize an experimental procedure for assessing the incompatibility of two qubit measurements. The experiment consists in a state discrimination task where either measurement is used according to some partial intermediate…

In this paper, we consider an open quantum system undergoing imperfect and indirect measurement. For quantum non-demolition (QND) measurement, we show that the system evolves on an appropriately chosen manifold and we express the exact…

Quantum Physics · Physics 2023-11-28 Ibrahim Ramadan , Nina H. Amini , Paolo Mason

Quantum Key Distribution (QKD) is a technique enabling provable secure communication but faces challenges in device characterization, posing potential security risks. Device-Independent (DI) QKD protocols overcome this issue by making…

Quantum Physics · Physics 2024-03-19 Michele Masini , Shubhayan Sarkar

Non-Hermitian quantum systems, governed by nonunitary evolution, offer powerful tools for manipulating quantum states through engineered loss. A prime example is coherent absorption, where quantum states undergo phase-dependent partial or…

Quantum metrology aims at achieving enhanced performance in measuring unknown parameters by utilizing quantum resources. Thus, quantum metrology is an important application of quantum technologies. Photonic systems can implement these…

Quantum Physics · Physics 2023-05-18 Madhura Ghosh Dastidar , Aprameyan Desikan , Vidya Praveen Bhallamudi

We investigate the quantum state discrimination task for sets of linear independent pure states with an intrinsic ordering. This structured discrimination problems allow for a novel scheme that provides a certified level of error, that is,…

Quantum Physics · Physics 2019-11-06 Esteban Martínez-Vargas , Ramon Munoz-Tapia

Recently, a novel framework for semi-device-independent quantum prepare-and-measure protocols has been proposed, based on the assumption of a limited distinguishability between the prepared quantum states. Here, we discuss the problem of…

Quantum Physics · Physics 2019-11-11 Weixu Shi , Yu Cai , Jonatan Bohr Brask , Hugo Zbinden , Nicolas Brunner

Superconducting resonators with high quality factors are extremely sensitive detectors of the complex impedance of materials and devices coupled to them. This capability has been used to measure losses in multiple different materials and,…

Quantum Physics · Physics 2025-07-01 Jared Gibson , Zhanzhi Jiang , Angela Kou

A generic model of measurement device which is able to directly measure commonly used quantum-state characteristics such as fidelity, overlap, purity and Hilbert-Schmidt distance for two general uncorrelated mixed states is proposed. In…

Quantum Physics · Physics 2009-11-07 Radim Filip