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We apply the notion of polar duality from convex geometry to the study of quantum covariance ellipsoids in symplectic phase space. We consider in particular the case of "quantum blobs" introduced in previous work; quantum blobs are the…

Quantum Physics · Physics 2022-08-24 Maurice de Gosson , Charlyne de Gosson

We generalise the Gaussian formalism of Continuous Variable (CV) systems to describe their interactions with qubits/qudits that result in quantum superpositions of Gaussian processes. To this end, we derive a new set of equations in closed…

Quantum Physics · Physics 2025-10-02 Lorenzo Braccini , Sougato Bose , Alessio Serafini

We derive an integral convex combination of product states for a range of separable Werner states. Our method consists of expanding the sought-after local density operators in terms of Wigner operators. For dimension d=2, our decomposition…

Quantum Physics · Physics 2008-09-03 R. G. Unanyan , H. Kampermann , D. Bruss

Based on the residual entanglement [9] (Phys. Rev. A \textbf{71}, 044301 (2005)), we present the global entanglement for a multipartite quantum state. The measure is shown to be also obtained by the bipartite partitions of the multipartite…

Quantum Physics · Physics 2009-11-13 Chang-shui Yu , He-shan Song

We find that the purifications of several Gaussian maximally mixed states (GMMSs) correspond to some Gaussian maximally entangled states (GMESs) in the continuous-variable regime. Here, we consider a two-mode squeezed vacuum (TMSV) state as…

Quantum Physics · Physics 2016-09-22 Kabgyun Jeong , Youngrong Lim

We introduce new representations to formulate quantum mechanics on noncommutative coordinate space, which explicitly display entanglement properties between degrees of freedom of different coordinate components and hence could be called…

High Energy Physics - Theory · Physics 2007-05-23 S. C. Jing , Q. Y. Liu , H. Y. Fan

We show, for the first time, that continuous dynamical decoupling can preserve the coherence of a two-qubit state as it evolves during a SWAP quantum operation. Hence, because the Heisenberg exchange interaction alone can be used for…

Quantum Physics · Physics 2010-05-12 Felipe F. Fanchini , Reginaldo d. J. Napolitano , Amir O. Caldeira

A $q$-deformed Weyl-Heisenberg algebra is used to define a deformed displacement operator giving rise to a naturally normalized nonlinear coherent states type. Robust maximally entangled deformed coherent states are studied and the effect…

Quantum Physics · Physics 2019-09-24 Mohamed Taha Rouabah , Noureddine Mebarki

We give an explicit tight lower bound for the entanglement of formation for arbitrary bipartite mixed states by using the convex hull construction of a certain function. This is achieved by revealing a novel connection among the…

Quantum Physics · Physics 2007-05-23 Kai Chen , Sergio Albeverio , Shao-Ming Fei

By using a coherent state quantization of paragrassmann variables, operators are constructed in finite Hilbert spaces. We thus obtain in a straightforward way a matrix representation of the paragrassmann algebra. This algebra of finite…

Quantum Physics · Physics 2012-01-04 M. El Baz , R. Fresneda , J. P. Gazeau , Y. Hassouni

Quantum state tomography, a fundamental tool for quantum physics, usually requires a number of state copies that scale exponentially with the system size, owing to the intricate quantum correlations between subsystems. We show that, in…

Quantum Physics · Physics 2025-12-22 Xiaobin Zhao , Pengcheng Liao , Francesco Anna Mele , Ulysse Chabaud , Quntao Zhuang

We prove that Wigner functions contain a symplectic connection. The latter covariantises the symplectic exterior derivative on phase space. We analyse the role played by this connection and introduce the notion of local symplectic…

Mathematical Physics · Physics 2008-11-26 J. M. Isidro

With any state of a multipartite quantum system its separability polytope is associated. This is an algebro-topological object (non-trivial only for mixed states) which captures the localisation of entanglement of the state. Particular…

Quantum Physics · Physics 2015-06-26 Roman R. Zapatrin

We propose in this work a practical approach to address the longstanding and challenging problem of quantum separability, leveraging the correlation matrices of generic observables. General separability conditions are obtained by dint of…

Quantum Physics · Physics 2025-05-07 Ma-Cheng Yang , Cong-Feng Qiao

In this work, we report on a novel quantum state reconstruction process based on the disentanglement algorithm. Using variational quantum circuits, we disentangle the quantum state to a product of computational zero states. Inverse…

Quantum Physics · Physics 2024-11-08 Juan Yao

The formalism of classical and quantum mechanics on phase space leads to symplectic and Heisenberg group representations, respectively. The Wigner functions give a representation of the quantum system using classical variables. The…

Quantum Physics · Physics 2007-05-23 Ajay Patwardhan

The well known Poisson Summation Formula is analysed from the perspective of the coherent state systems associated with the Heisenberg--Weyl group. In particular, it is shown that the Poisson summation formula may be viewed abstractly as a…

Quantum Physics · Physics 2009-11-13 Arvind , S. Chaturvedi , N. Mukunda , R. Simon

A Gaussian degree of entanglement for a symmetric two-mode Gaussian state can be defined as its distance to the set of all separable two-mode Gaussian states. The principal property that enables us to evaluate both Bures distance and…

Quantum Physics · Physics 2009-11-13 Paulina Marian , Tudor A. Marian

We discuss the concept of how entanglement changes with respect to different factorizations of the total algebra which describes the quantum states. Depending on the considered factorization a quantum state appears either entangled or…

Quantum Physics · Physics 2011-11-15 Walter Thirring , Reinhold A. Bertlmann , Philipp Köhler , Heide Narnhofer

Given a finite group G with a bilocal representation, we investigate the bipartite entanglement in the state constructed from the group algebra of G acting on a separable reference state. We find an upper bound for the von Neumann entropy…

Quantum Physics · Physics 2007-05-23 Alioscia Hamma , Radu Ionicioiu , Paolo Zanardi
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