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We present a quasipolynomial-time algorithm for solving the weak membership problem for the convex set of separable, i.e. non-entangled, bipartite density matrices. The algorithm decides whether a density matrix is separable or whether it…

Quantum Physics · Physics 2011-06-13 Fernando G. S. L. Brandao , Matthias Christandl , Jon Yard

We develop separability criteria to identify non-$k$-separability $(k = 2,3,\ldots,n)$ and genuine multipartite entanglement in different classes of mixed $n$-partite quantum states using elements of density matrices. With the help of these…

Quantum Physics · Physics 2015-06-23 N. Ananth , V. K. Chandrasekar , M. Senthilvelan

We theoretically study the Hilbert space structure of two neighbouring P donor electrons in silicon-based quantum computer architectures. To use electron spins as qubits, a crucial condition is the isolation of the electron spins from their…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 L. M. Kettle , Hsi-Sheng Goan , Sean C. Smith

We show that, in finite dimensions, around any $m$-partite product state $\rho_{\rm prod}=\rho_1\otimes...\otimes\rho_m$, there exists an ellipsoid of separable states centered around $\rho_{\rm prod}$. This separable ellipsoid contains the…

Quantum Physics · Physics 2025-07-30 Robin Y. Wen , Gilles Parez , Liuke Lyu , William Witczak-Krempa , Achim Kempf

It is shown that any separable state on Hilbert space ${\cal H}={\cal H}_1\otimes{\cal H}_2$, can be written as a convex combination of N pure product states with $N\leq (dim{\cal H})^2$. Then a new separability criterion for mixed states…

Quantum Physics · Physics 2009-10-30 Pawel Horodecki

In this paper, we mainly discuss the separability of $n$-partite quantum states from elements of density matrices. Practical separability criteria for different classes of $n$-qubit and $n$-qudit quantum states are obtained. Some of them…

Quantum Physics · Physics 2011-05-06 Ting Gao , Yan Hong

A conceptually simpler proof of the separability criterion for two-qubit systems, which is referred to as "Hefei inequality" in literature, is presented. This inequality gives a necessary and sufficient separability criterion for any mixed…

Quantum Physics · Physics 2017-04-03 Kazuo Fujikawa , C. H. Oh

We report on experimental measurement of the Hilbert-Schmidt distance between two two-qubit states by many-particle interference. We demonstrate that our three-step method for measuring distances in Hilbert space is far less complex than…

Quantum Physics · Physics 2021-12-28 Vojtěch Trávníček , Karol Bartkiewicz , Antonín Černoch , Karel Lemr

In this paper, we study the linear separability problem for stochastic geometric objects under the well-known unipoint/multipoint uncertainty models. Let $S=S_R \cup S_B$ be a given set of stochastic bichromatic points, and define $n =…

Computational Geometry · Computer Science 2016-04-06 Jie Xue , Yuan Li , Ravi Janardan

In previously exhibited hidden variable models of quantum state preparation and measurement, the number of continuous hidden variables describing the actual state of a single realization is never smaller than the quantum state manifold…

Quantum Physics · Physics 2011-03-23 Alberto Montina

In this paper, we discuss the partial separability and its criteria problems of multipartite qubit mixed-states. First we strictly define what is the partial separability of a multipartite qubit system. Next we give a reduction way from…

Quantum Physics · Physics 2007-05-23 Zai-Zhe Zhong

The evolution of multiple-input, multiple-output (MIMO) systems requires the efficient detection algorithms to overcome the exponential computational complexity of optimal maximum likelihood detection. Reformulating MIMO detection as a…

Information Theory · Computer Science 2026-05-13 Seyedkhashayar Hashemi , Elisabetta Valiante , Ignacio Rozada , Moslem Noori

We describe explicitly the algebra of polynomial functions on the Hilbert space of four qubit states which are invariant under the SLOCC group $SL(2,{\mathbb C})^{4}$. From this description, we obtain a closed formula for the…

Quantum Physics · Physics 2013-02-12 J. -G. Luque , J. -Y. Thibon

The study of conditional $q$-entropies in composite quantum systems has recently been the focus of considerable interest, particularly in connection with the problem of separability. The $q$-entropies depend on the density matrix $\rho$…

Quantum Physics · Physics 2009-11-10 J. Batle , A. R. Plastino , M. Casas , A. Plastino

Strongly correlated quantum systems give rise to many exotic physical phenomena, including high-temperature superconductivity. Simulating these systems on quantum computers may avoid the prohibitively high computational cost incurred in…

Quantum Physics · Physics 2020-10-19 Frank Arute , Kunal Arya , Ryan Babbush , Dave Bacon , Joseph C. Bardin , Rami Barends , Andreas Bengtsson , Sergio Boixo , Michael Broughton , Bob B. Buckley , David A. Buell , Brian Burkett , Nicholas Bushnell , Yu Chen , Zijun Chen , Yu-An Chen , Ben Chiaro , Roberto Collins , Stephen J. Cotton , William Courtney , Sean Demura , Alan Derk , Andrew Dunsworth , Daniel Eppens , Thomas Eckl , Catherine Erickson , Edward Farhi , Austin Fowler , Brooks Foxen , Craig Gidney , Marissa Giustina , Rob Graff , Jonathan A. Gross , Steve Habegger , Matthew P. Harrigan , Alan Ho , Sabrina Hong , Trent Huang , William Huggins , Lev B. Ioffe , Sergei V. Isakov , Evan Jeffrey , Zhang Jiang , Cody Jones , Dvir Kafri , Kostyantyn Kechedzhi , Julian Kelly , Seon Kim , Paul V. Klimov , Alexander N. Korotkov , Fedor Kostritsa , David Landhuis , Pavel Laptev , Mike Lindmark , Erik Lucero , Michael Marthaler , Orion Martin , John M. Martinis , Anika Marusczyk , Sam McArdle , Jarrod R. McClean , Trevor McCourt , Matt McEwen , Anthony Megrant , Carlos Mejuto-Zaera , Xiao Mi , Masoud Mohseni , Wojciech Mruczkiewicz , Josh Mutus , Ofer Naaman , Matthew Neeley , Charles Neill , Hartmut Neven , Michael Newman , Murphy Yuezhen Niu , Thomas E. O'Brien , Eric Ostby , Bálint Pató , Andre Petukhov , Harald Putterman , Chris Quintana , Jan-Michael Reiner , Pedram Roushan , Nicholas C. Rubin , Daniel Sank , Kevin J. Satzinger , Vadim Smelyanskiy , Doug Strain , Kevin J. Sung , Peter Schmitteckert , Marco Szalay , Norm M. Tubman , Amit Vainsencher , Theodore White , Nicolas Vogt , Z. Jamie Yao , Ping Yeh , Adam Zalcman , Sebastian Zanker

This paper characterizes two forms of separability of pure states of systems of n qubits: (i) into a tensor product of n qubit states, and (ii), into a tensor product of 2 subsystems states of p and q qubits respectively with p+q=n. For…

Quantum Physics · Physics 2007-05-23 Philippe Jorrand , Mehdi Mhalla

We study the evolution of the hybrid entangled squeezed states of the qubit-oscillator system in the strong coupling domain. Following the adiabatic approximation we obtain the reduced density matrices of the qubit and the oscillator…

Quantum Physics · Physics 2016-10-18 M. Balamurugan , R. Chakrabarti , B. Virgin Jenisha

We employ the Margenau-Hill (MH) correspondence rule for associating classical functions with quantum operators to construct quasi-probability mass functions. Using this we obtain the fuzzy one parameter quasi measurement operator (QMO)…

Quantum Physics · Physics 2023-04-28 Seeta Vasudevrao , H. S. Karthik , I. Reena , Sudha , A. R. Usha Devi

We imagine an experiment on an unknown quantum mechanical system in which the system is prepared in various ways and a range of measurements are performed. For each measurement M and preparation rho the experimenter can determine, given…

Quantum Physics · Physics 2009-01-20 Stephanie Wehner , Matthias Christandl , Andrew C. Doherty

In this work, we consider the weighted difference of two independent complex Wishart matrices and derive the joint probability density function of the corresponding eigenvalues in a finite-dimension scenario using two distinct approaches.…

Mathematical Physics · Physics 2020-11-17 Santosh Kumar , S. Sai Charan