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We consider a bipartite mixed state of the form, $\rho =\sum_{\alpha, \beta =1}^{l}a_{\alpha \beta} | \psi_{\alpha}> < \psi_ \beta}| $, where $| \psi_{\alpha}>$ are normalized bipartite state vectors, and matrix $(a_{\alpha \beta})$ is…

Quantum Physics · Physics 2007-05-23 Tohya Hiroshima , Masahito Hayashi

We define and study a new type of quantum oracle, the quantum conditional oracle, which provides oracle access to the conditional probabilities associated with an underlying distribution. Amongst other properties, we (a) obtain speed-ups…

Quantum Physics · Physics 2016-09-07 Imdad S. B. Sardharwalla , Sergii Strelchuk , Richard Jozsa

In this paper we consider a quantum computational variant of nondeterminism based on the notion of a quantum proof, which is a quantum state that plays a role similar to a certificate in an NP-type proof. Specifically, we consider quantum…

Computational Complexity · Computer Science 2007-05-23 John Watrous

Two particles are identical if all their intrinsic properties, such as spin and charge, are the same, meaning that no quantum experiment can distinguish them. In addition to the well known principles of quantum mechanics, understanding…

Quantum Physics · Physics 2021-05-11 Alessio Benavoli , Alessandro Facchini , Marco Zaffalon

Given a mixture of states, finding a way to optimally discriminate its elements is a prominent problem in quantum communication theory. In this paper, we will address mixtures of density operators that are unitarily equivalent via elements…

Mathematical Physics · Physics 2024-02-09 Alberto Acevedo , Janek Wehr

Entangled quantum states are essential ingredients for many quantum technologies, but they must be validated before they are used. As a full characterization is prohibitively resource-intensive, recent work has focused on developing methods…

We consider entanglement detection for quantum key distribution systems that use two signal states and continuous variable measurements. This problem can be formulated as a separability problem in a qubit-mode system. To verify…

Quantum Physics · Physics 2007-05-23 Johannes Rigas , Otfried Gühne , Norbert Lütkenhaus

We study the computational complexity of quantum state isomorphism problems under group actions: given two quantum circuits that prepare pure or mixed states, decide whether the two states are related by a group action. This can be seen as…

Quantum Physics · Physics 2026-05-14 Alexandru Gheorghiu , Dale Jacobs , Saeed Mehraban , Arsalan Motamedi

A relationship between a recently introduced multipartite entanglement measure, state mixedness, and spin-flip symmetry is established for any finite number of qubits. It is also shown that, within those classes of states invariant under…

Quantum Physics · Physics 2009-11-10 Gregg Jaeger , Alexander V. Sergienko , Bahaa E. A. Saleh , Malvin C. Teich

Every quantum state can be represented as a probability distribution over the outcomes of an informationally complete measurement. But not all probability distributions correspond to quantum states. Quantum state space may thus be thought…

Quantum Physics · Physics 2011-02-14 D. M. Appleby , Asa Ericsson , Christopher A. Fuchs

Entanglement, or quantum inseparability, is a crucial resource in quantum information applications, and therefore the experimental generation of separated yet entangled systems is of paramount importance. Experimental demonstrations of…

Quantum Physics · Physics 2009-11-07 M. G. Raymer , A. C. Funk , B. C. Sanders , H. de Guise

Quantum steering is the phenomenon whereby one party (Alice) proves entanglement by "steering'' the system of another party (Bob) into distinct ensembles of states, by performing different measurements on her subsystem. Here, we investigate…

Quantum Physics · Physics 2024-04-04 Qiu-Cheng Song , Travis J. Baker , Howard M. Wiseman

Quantum computers are now on the brink of outperforming their classical counterparts. One way to demonstrate the advantage of quantum computation is through quantum random sampling performed on quantum computing devices. However, existing…

We present a necessary and sufficient product criterion for bipartite quantum states based on the rank of realignment matrix of density matrix. Then, this approach is generalized to multipartite systems. We first introduce the concept of…

Quantum Physics · Physics 2018-02-27 Xianfei Qi , Ting Gao , Fengli Yan

We investigate a-priori detection probabilities of genuine multipartite entanglement (GME). Even if one does not have knowledge about the basis in which a state is produced by a source, how a channel decoheres it or about the very working…

Quantum Physics · Physics 2013-08-01 A. Gabriel , Ł. Rudnicki , B. C. Hiesmayr

A geometrical characterization of robustly separable (that is, remaining separable under sufficiently small variiations) mixed states of a bipartite quantum system is given. It is shown that the density matrix of any such state can be…

Quantum Physics · Physics 2007-05-23 Roman R. Zapatrin

We use the probability of error as a measure of distinguishability between two pure and two mixed symmetric coherent states in the context of continuous variable quantum cryptography. We show that the two mixed symmetric coherent states (in…

Quantum Physics · Physics 2007-05-23 Christian Weedbrook , Mile Gu , Andrew M. Lance , Thomas Symul , Ping Koy Lam , Timothy C. Ralph

We introduce a family of highly symmetric bipartite quantum states in arbitrary dimensions. It consists of all states that are invariant under local phase rotations and local cyclic permutations of the basis. We solve the separability…

Quantum Physics · Physics 2022-09-05 Marcel Seelbach Benkner , Jens Siewert , Otfried Gühne , Gael Sentís

We describe a generalization of the group testing problem termed symmetric group testing. Unlike in classical binary group testing, the roles played by the input symbols zero and one are "symmetric" while the outputs are drawn from a…

Information Theory · Computer Science 2011-08-16 Amin Emad , Jun Shen , Olgica Milenkovic

Measurement incompatibility and bipartite quantum steering are known to display a strong connection: a set of measurements is incompatible if and only if it can lead to bipartite steering. Despite such a close link between these concepts in…

Quantum Physics · Physics 2026-03-27 Lucas E. A. Porto , Lucas Tendick , Daniel Cavalcanti , Roope Uola , Marco Túlio Quintino