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Consider a situation in which a quantum system is secretly prepared in a state chosen from the known set of states. We present a principle that gives a definite distinction between the operations that preserve the states of the system and…

Quantum Physics · Physics 2007-05-23 Masato Koashi , Nobuyuki Imoto

The purpose of quantum tomography is to determine an unknown quantum state from measurement outcome statistics. There are two obvious ways to generalize this setting. First, our task need not be the determination of any possible input state…

Quantum Physics · Physics 2014-02-11 Claudio Carmeli , Teiko Heinosaari , Jussi Schultz , Alessandro Toigo

We propose an efficient decomposition scheme for a quantum receiver that attains the Helstrom bound in the low-photon regime for discriminating binary coherent states. Our method, which avoids feedback as used in Dolinar's case, breaks down…

The conventional approach to understanding the characteristics of an unknown quantum state involves having numerous identical independent copies of the system in that state. However, we demonstrate that gleaning insights into specific…

Quantum Physics · Physics 2024-04-09 Nengkun Yu

Mutually unbiased bases determine an optimal set of measurements to extract complete information about the quantum state of a system. However, quite often a priori information about the state exist, making some of the measurement bases…

Quantum Physics · Physics 2015-06-12 A. B. Klimov , G. Bjork , L. L. Sanchez-Soto

A new purification scheme is proposed which applies to arbitrary dimensional bipartite quantum systems. It is based on the repeated application of a special class of nonlinear quantum maps and a single, local unitary operation. This special…

Quantum Physics · Physics 2009-11-07 Gernot Alber , Aldo Delgado , Nicolas Gisin , Igor Jex

In this paper we study the state determination for composite systems of two spatial qubits. We show, theoretically, that one can use the technique of quantum tomography to reconstruct the density matrixes of these systems. This tomographic…

Quantum Physics · Physics 2009-11-13 G. Lima , F. A. Torres-Ruiz , L. Neves , A. Delgado , C. Saavedra , S. Padua

According to the fundamental laws of quantum optics, noise is necessarily added to the system when one tries to clone or amplify a quantum state. However, it has recently been shown that the quantum noise related to the operation of a…

Quantum Physics · Physics 2013-12-18 Mikko Partanen , Teppo Häyrynen , Jani Oksanen , Jukka Tulkki

In this paper we consider memoryless one-bit compressed sensing with randomly subsampled Gaussian circulant matrices. We show that in a small sparsity regime and for small enough accuracy $\delta$, $m\sim \delta^{-4} s\log(N/s\delta)$…

Information Theory · Computer Science 2017-10-11 Sjoerd Dirksen , Hans Christian Jung , Holger Rauhut

In this paper, a new class of band matrices is considered where the entries of each non-zero band form a sequence with two limit points. The compact perturbation technique is used to study the spectrum over the $\ell_{p}, (1<p<\infty)$…

Spectral Theory · Mathematics 2025-01-22 Jyoti Rani , Arnab Patra , P D Srivastava

We present a method that outputs a sequence of simple unitary operations to prepare a given quantum state that is a generalized coherent state. Our method takes as inputs the expectation values of some relevant observables on the state to…

Quantum Physics · Physics 2020-01-08 Rolando D. Somma

Variational algorithms are a promising paradigm for utilizing near-term quantum devices for modeling electronic states of molecular systems. However, previous bounds on the measurement time required have suggested that the application of…

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

For quantum systems with a total dimension greater than six, the positive partial transposition (PPT) criterion is sufficient but not necessary to decide the non-separability of quantum states. Here, we present an Automated Machine Learning…

Quantum Physics · Physics 2021-09-22 Caio B. D. Goes , Askery Canabarro , Eduardo I. Duzzioni , Thiago O. Maciel

We demonstrate that important information about linear optical circuits can be obtained through the phase shift induced by integrated optical resonators. As a proof of principle, the phase of an unbalanced Mach-Zehnder interferometer is…

Optics · Physics 2016-11-03 Menno Poot , Hong X. Tang

Quantum circuit cutting has been proposed to help execute large quantum circuits using only small and noisy machines. Intuitively, cutting a qubit wire can be thought of as classically passing information of a quantum state along each…

Electrical engineers and physicists are naturally very interested in noise in circuits, amplifiers and detectors. With the advent of quantum computation and other high frequency electronics operating at low temperatures, we have entered a…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 R. J. Schoelkopf , A. A. Clerk , S. M. Girvin , K. W. Lehnert , M. H. Devoret

A basic diagnostic of entanglement in mixed quantum states is known as the positive partial transpose (PT) criterion. Such criterion is based on the observation that the spectrum of the partially transposed density matrix of an entangled…

Statistical Mechanics · Physics 2019-09-25 Hassan Shapourian , Paola Ruggiero , Shinsei Ryu , Pasquale Calabrese

We propose a protocol for conditional suppression of losses in direct quantum state transmission over a lossy quantum channel. The method works by noiselessly attenuating the input state prior to transmission through a lossy channel…

I prove a semiparametric Bernstein-von Mises theorem for a partially linear regression model with independent priors for the low-dimensional parameter of interest and the infinite-dimensional nuisance parameters. My result avoids a…

Statistics Theory · Mathematics 2025-04-08 Christopher D. Walker