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We address the problem of completely characterizing multi-particle states including loss of information to unobserved degrees of freedom. In systems where non-classical interference plays a role, such as linear-optics quantum gates, such…

Quantum Physics · Physics 2009-11-13 R. B. A. Adamson , L. K. Shalm , M. W. Mitchell , A. M. Steinberg

Laser light is widely used for communication and sensing applications, so the optimal discrimination of coherent states--the quantum states of light emitted by a laser--has immense practical importance. However, quantum mechanics imposes a…

Quantum Physics · Physics 2013-05-24 Marcus P. da Silva , Saikat Guha , Zachary Dutton

Pure states are usually used to observe quantum phenomena. In this study, we show that a quantum superposition of spatially displaced mixed cat states can be generated within an optical waveguide via nonparaxial unitary evolution of the…

Quantum Physics · Physics 2025-12-01 N. I. Petrov

We consider unitary evolution of finite bipartite quantum systems and study time dependence of purity for initial cat states -- coherent superpositions of Gaussian wave-packets. We derive explicit formula for purity in systems with nonzero…

Quantum Physics · Physics 2009-11-11 Marko Znidaric , Tomaz Prosen

We describe a purely algebraic method for finding the best separable approximation to a mixed state of a composite 2x2 quantum system, consisting of a decomposition of the state into a linear combination of a mixed separable part and a pure…

Quantum Physics · Physics 2009-11-07 Thomas Wellens , Marek Kus

While the implementation of single particle coherent diffraction imaging for non-crystalline particles is complicated by current limitations in photon flux, hit rate, and sample delivery a concept of many-particle coherent diffraction…

Disordered Systems and Neural Networks · Physics 2013-02-22 R. P. Kurta , R. Dronyak , M. Altarelli , E. Weckert , I. A. Vartanyants

Phase retrieval is in general a non-convex and non-linear task and the corresponding algorithms struggle with the issue of local minima. We consider the case where the measurement samples within typically very small and disconnected subsets…

Signal Processing · Electrical Eng. & Systems 2022-06-28 Jonas Kornprobst , Alexander Paulus , Josef Knapp , Thomas F. Eibert

Degenerate quantum codes are codes that do not reveal the complete error syndrome. Their ability to conceal the complete error syndrome makes them powerful resources in certain quantum information processing tasks. In particular, the most…

Quantum Physics · Physics 2008-08-15 K. H. Ho , H. F. Chau

We devise a scheme that protects quantum coherent states of light from probabilistic losses, thus achieving the first continuous-variable quantum erasure-correcting code. If the occurrence of erasures can be probed, then the decoder…

Quantum Physics · Physics 2009-11-13 J. Niset , U. L. Andersen , N. J. Cerf

Coherent generation of indistinguishable single photons is crucial for many quantum communication and processing protocols. Solid-state realizations of two-level atomic transitions or three-level spin-$\Lambda$ systems offer significant…

Mesoscale and Nanoscale Physics · Physics 2019-12-03 Zhe-Xian Koong , Dale Scerri , Markus Rambach , Ted S. Santana , Suk-In Park , Jin D. Song , Erik M. Gauger , Brian D. Gerardot

Integrated single-photon detectors open new possibilities for monitoring inside quantum photonic circuits. We present a concept for the in-line measurement of spatially-encoded multi-photon quantum states, while keeping the transmitted ones…

Information multiplexing is important for biomedical imaging and chemical sensing. In this paper, we report a microscopy imaging technique, termed state-multiplexed Fourier ptychography (FP), for information multiplexing and coherent-state…

Optics · Physics 2014-05-12 Siyuan Dong , Radhika Shiradkar , Pariksheet Nanda , Guoan Zheng

Coherent states of the quantum electromagnetic field, the quantum description of ideal laser light, are prime candidates as information carriers for optical communications. A large body of literature exists on their quantum-limited…

Quantum Physics · Physics 2023-06-07 Jasminder S. Sidhu , Michael S. Bullock , Saikat Guha , Cosmo Lupo

We propose a simple method for measuring the populations and the relative phase in a coherent superposition of two atomic states. The method is based on coupling the two states to a third common (excited) state by means of two laser pulses,…

Quantum Physics · Physics 2009-10-31 N. V. Vitanov , B. W. Shore , R. G. Unanyan , K. Bergmann

Entangled coherent states are useful for various applications in quantum information processing but they are are sensitive to loss. We propose a scheme to generate distributed entangled coherent states over a lossy environment in such a way…

Quantum Physics · Physics 2015-06-17 A. P. Lund , T. C. Ralph , H. Jeong

We introduce a general mapping for encoding quantum communication protocols involving pure states of multiple qubits, unitary transformations, and projective measurements into another set of protocols that employ coherent states of light in…

Quantum Physics · Physics 2014-11-05 Juan Miguel Arrazola , Norbert Lütkenhaus

We introduce harmonization, an ensembling method that combines several "noisy" decoders to generate highly accurate decoding predictions. Harmonized ensembles of MWPM-based decoders achieve lower logical error rates than their individual…

Quantum Physics · Physics 2024-03-18 Noah Shutty , Michael Newman , Benjamin Villalonga

The coherent-state qubit is a promising candidate for optical quantum information processing due to its nearly-deterministic nature of the Bell-state measurement (BSM). However, its non-orthogonality incurs difficulties such as failure of…

Quantum Physics · Physics 2021-12-23 Seok-Hyung Lee , Seung-Woo Lee , Hyunseok Jeong

Homodyne detection is considered as a way to improve the efficiency of communication near the single-photon level. The current lack of commercially available {\it infrared} photon-number detectors significantly reduces the mutual…

Quantum Physics · Physics 2009-11-07 K. Nemoto , S. L. Braunstein

The key to optical analogy to a multi-particle quantum system is the scalable property. Optical elds modulated with pseudorandom phase sequences is an interesting solution. By utilizing the properties of pseudorandom sequences, mixing…

Quantum Physics · Physics 2016-09-29 Jian Fu , Wenjiang Li , Yongzheng Ye