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Quantifying entanglement is a work in progress which is important for the active field of quantum information and computation. A measure of bipartite pure state entanglement is proposed here, named entanglement coherence, which is…

Quantum Physics · Physics 2022-02-15 Neha Pathania , Tabish Qureshi

Coherent superposition states of a mesoscopic quantum object play a major role in our understanding of the quantum to classical boundary, as well as in quantum-enhanced metrology and computing. However, their practical realization and…

We present a general method to characterize the quantum correlations obtained after local measurements on multipartite systems. Sufficient conditions for a quantum system to be fully-nonlocal according to a given partition, as well as being…

Quantum Physics · Physics 2015-05-14 Mafalda L. Almeida , Daniel Cavalcanti , Valerio Scarani , Antonio Acin

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

Determining the relationship between composite systems and their subsystems is a fundamental problem in quantum physics. In this paper we consider the spectra of a bipartite quantum state and its two marginal states. To each spectrum we can…

Quantum Physics · Physics 2007-05-23 Matthias Christandl , Graeme Mitchison

We demonstrate that the spin state of solid-state emitters inside micropillar cavities can serve as measure qubits in syndrome measurements. The photons, acting as data qubits, interact with the spin state in the microcavity and the total…

Quantum Physics · Physics 2024-10-11 Elena Callus , Pieter Kok

Schwinger's algebra of selective measurements has a natural interpretation in terms of groupoids. This approach is pushed forward in this paper to show that the theory of coherent states has a natural setting in the framework of groupoids.…

Quantum Physics · Physics 2020-03-18 Fabio Di Cosmo , Alberto Ibort , Giuseppe Marmo

p-Mechanics is a consistent physical theory which describes both quantum and classical mechanics simultaneously. We continue the development of p-mechanics by introducing the concept of states. The set of coherent states we introduce allow…

Quantum Physics · Physics 2007-05-23 Alastair Brodlie

We consider the evaluation of the quantum discord and other related measures of quantum correlations in a system formed by a spin 1 and a complementary spin system. A characterization of general projective measurements in such system in…

Quantum Physics · Physics 2015-06-05 R. Rossignoli , J. M. Matera , N. Canosa

Collisions in a thermal gas are perceived as random or incoherent as a consequence of the large numbers of initial and final quantum states accessible to the system. In a quantum gas, e.g. a Bose-Einstein condensate or a degenerate Fermi…

Other Condensed Matter · Physics 2015-06-25 Ming-Shien Chang , Qishu Qin , Wenxian Zhang , Li You , Michael S. Chapman

We introduce the nonlinear spin coherent state via its ladder operator formalism and propose a type of nonlinear spin coherent state by the nonlinear time evolution of spin coherent states. By a new version of spectroscopic squeezing…

Quantum Physics · Physics 2009-11-07 Xiaoguang Wang

We analyze detailed properties of BPS coherent states and their connection to gravity. We interpret the group integral coherent state as a path integral over auxiliary variables coupled to the elementary letters of the theory. The…

High Energy Physics - Theory · Physics 2023-02-10 Hai Lin

Some new identities for quantum variance and covariance involving commutators are presented, in which the density matrix and the operators are treated symmetrically. A measure of entanglement is proposed for bipartite systems, based on…

Quantum Physics · Physics 2009-11-06 R I A Davis , R Delbourgo , P D Jarvis

Spin ensembles play a pivotal role in various quantum applications such as metrology and simulating many-body physics. Recent research has proposed utilizing spin cat states to encode logical quantum information, with logical lifetimes…

Quantum Physics · Physics 2025-04-10 Wai-Keong Mok , Leong-Chuan Kwek , Steven Touzard

We study a bipartite collective spin-$1$ model with exchange interaction between the spins. The bipartite nature of the model manifests itself by the spins being divided into two equal-sized subsystems; within each subsystem the spin-spin…

Statistical Mechanics · Physics 2021-07-07 Dávid Jakab , Zoltán Zimborás

We consider dual unitary operators and their multi-leg generalizations that have appeared at various places in the literature. These objects can be related to multi-party quantum states with special entanglement patterns: the sites are…

Quantum Physics · Physics 2022-10-25 Márton Mestyán , Balázs Pozsgay , Ian M. Wanless

Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing,…

Quantum Physics · Physics 2016-02-25 Nathan Killoran , Frank E. S. Steinhoff , Martin B. Plenio

Multiparty quantum states are useful for a variety of quantum information and computation protocols. We define a multiparty entanglement measure based on local measurements on a multiparty quantum state, and an entanglement measure averaged…

Graph states are multi-particle entangled states that correspond to mathematical graphs, where the vertices of the graph take the role of quantum spin systems and edges represent Ising interactions. They are many-body spin states of…

Quantum Physics · Physics 2007-05-23 M. Hein , J. Eisert , H. J. Briegel

On the example of a quantum oscillator the connection of the dynamical coherent state with the phase symmetry breaking and the existence of the nondissipative motion is considered. In multiparticle systems of interacting particles similar…

Quantum Physics · Physics 2024-08-13 Yu. M. Poluektov