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The degree to which a pure quantum state is entangled can be characterized by the distance or angle to the nearest unentangled state. This geometric measure of entanglement, already present in a number of settings [A. Shimony, Ann. NY.…

Quantum Physics · Physics 2007-05-23 Tzu-Chieh Wei , Paul M. Goldbart

Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition--------quantum coherence or quantum superposition. In this paper, we attempt to give an alternative…

Quantum Physics · Physics 2014-09-23 Chang-shui Yu , Yang Zhang , Haiqing Zhao

Quantum states may exhibit asymmetry with respect to the action of a given group. Such an asymmetry of states can be considered as a resource in applications such as quantum metrology, and it is a concept that encompasses quantum coherence…

Quantum coherence is the most fundamental feature of quantum mechanics. The usual understanding of it depends on the choice of the basis, that is, the coherence of the same quantum state is different within different reference framework. To…

Quantum Physics · Physics 2017-04-17 Chang-shui Yu , Yi-ren Yang , Bao-qing Guo

We present a measure of quantum coherence by employing the concept of noncommutativity of operators in quantum mechanics. We analyse the behaviour of this noncommutative coherence and underline its similarities and differences with the…

Quantum Physics · Physics 2020-04-06 Shubhalakshmi S , Ujjwal Sen

If the system is known to be in one of two non-orthogonal quantum states, $|\psi_1\rangle$ or $|\psi_2\rangle$, $\mathcal{PT}$-symmetric quantum mechanics can discriminate them, \textit{in principle}, by a single measurement. We extend this…

Quantum Physics · Physics 2020-08-18 Yaroslav Balytskyi , Sang-Yoon Chang , Anatoliy Pinchuk , Manohar Raavi

The degree to which a pure quantum state is entangled can be characterized by the distance or angle to the nearest unentangled state. This geometric measure of entanglement, already present in a number of settings (see Shimony 1995 and…

Quantum Physics · Physics 2009-11-10 Tzu-Chieh Wei , Paul M. Goldbart

The minimal Bures distance of a quantum state of a bipartite system AB to the set of classical states for subsystem A defines a geometric measure of quantum discord. When A is a qubit, we show that this geometric quantum discord is given in…

Quantum Physics · Physics 2013-12-24 Dominique Spehner , Miguel Orszag

Error probability is a popular and well-studied optimization criterion in discriminating non-orthogonal quantum states. It captures the threat from an adversary who can only query the actual state once. However, when the adversary is able…

Quantum Physics · Physics 2015-05-11 Weien Chen , Yongzhi Cao , Hanpin Wang , Yuan Feng

If the system is known to be in one of two non-orthogonal quantum states, $|\psi_1\rangle$ or $|\psi_2\rangle$, it is not possible to discriminate them by a single measurement due to the unitarity constraint. In a regular Hermitian quantum…

Quantum Physics · Physics 2021-06-08 Yaroslav Balytskyi , Manohar Raavi , Anatoliy Pinchuk , Sang-Yoon Chang

The manifold of pure quantum states is a complex projective space endowed with the unitary-invariant geometry of Fubini and Study. According to the principles of geometric quantum mechanics, the detailed physical characteristics of a given…

Quantum Physics · Physics 2015-06-26 Dorje C. Brody , Lane P. Hughston

The convenience of coherent state representation is discussed from the viewpoint of what is in a broad sense called the measurement problem in quantum mechanics. Standard quantum theory in coherent state representation is intrinsically…

Quantum Physics · Physics 2008-02-03 Lajos Diosi

We investigate the generic aspects of quantum coherence guided by the concentration of measure phenomenon. We find the average relative entropy of coherence of pure quantum states sampled randomly from the uniform Haar measure and show that…

Quantum Physics · Physics 2016-03-30 Uttam Singh , Lin Zhang , Arun Kumar Pati

The concept of p-orthogonality (1=< p =< n) between n-particle states is introduced. It generalizes common orthogonality, which is equivalent to n-orthogonality, and strong orthogonality between fermionic states, which is equivalent to…

Quantum Physics · Physics 2008-03-17 Patrick Cassam-Chenaï

Quantifying coherence is a key task in both quantum mechanical theory and practical applications. Here, a reliable quantum coherence measure is presented by utilizing the quantum skew information of the state of interest subject to a…

Quantum Physics · Physics 2017-05-03 Chang-shui Yu

Computational complexity is a new quantum information concept that may play an important role in holography and in understanding the physics of the black hole interior. We consider quantum computational complexity for $n$ qubits using…

High Energy Physics - Theory · Physics 2021-05-21 Roberto Auzzi , Stefano Baiguera , G. Bruno De Luca , Andrea Legramandi , Giuseppe Nardelli , Nicolò Zenoni

Nowadays, geometric tools are being used to treat a huge class of problems of quantum information science. By understanding the interplay between the geometry of the state space and information-theoretic quantities, it is possible to obtain…

Quantum Physics · Physics 2015-04-27 Diego Paiva Pires , Lucas C. Céleri , Diogo O. Soares-Pinto

Quantum coherence is an essential ingredient in quantum information processing and plays a central role in emergent fields such as nanoscale thermodynamics and quantum biology. However, our understanding and quantitative characterization of…

A general state of an $m\otimes n$ system is a classical-quantum state if and only if its associated $A$-correlation matrix (a matrix constructed from the coherence vector of the party $A$, the correlation matrix of the state, and a…

Quantum Physics · Physics 2016-04-19 S. Javad Akhtarshenas , Hamidreza Mohammadi , Saman Karimi , Zahra Azmi

The measurement process in quantum mechanics is usually described by the von Neumann projection postulate, which forms a basic constituent of the laws of quantum mechanics. Since this postulate requires the outside observer of the system,…

Quantum Physics · Physics 2009-11-11 Masahiro Morikawa , Akika Nakamichi