Results 21 to 30 of about 6,845,583 (296)
Positive maps that are not completely positive [PDF]
Physical Review A, 2000 The concept of the {\em half density matrix} is proposed. It unifies the quantum states which are described by density matrices and physical processes which are described by completely positive maps. With the help of the half-density-matrix representation of Hermitian linear map, we show that every positive map which is not completely positive is a ...
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On the Debate Concerning the Proper Characterisation of Quantum Dynamical Evolution [PDF]
, 2012 There has been a long-standing and sometimes passionate debate between physicists over whether a dynamical framework for quantum systems should incorporate not completely positive (NCP) maps in addition to completely positive (CP) maps.
Cuffaro, Michael E. +3 more
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On the Alberti-Uhlmann Condition for Unital Channels [PDF]
Quantum, 2020 We address the problem of existence of completely positive trace preserving (CPTP) maps between two sets of density matrices. We refine the result of Alberti and Uhlmann and derive a necessary and sufficient condition for the existence of a unital ...
Sagnik Chakraborty +3 more
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Completely positive module maps and completely positive extreme maps [PDF]
Proceedings of the American Mathematical Society, 1996 Let A , B A,B
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Quantum Weak Invariants: Dynamical Evolution of Fluctuations and Correlations
Entropy, 2020 Weak invariants are time-dependent observables with conserved expectation values. Their fluctuations, however, do not remain constant in time. On the assumption that time evolution of the state of an open quantum system is given in terms of a completely ...
Zeyi Shi, Sumiyoshi Abe
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Infinite-Dimensionality in Quantum Foundations: W*-algebras as Presheaves over Matrix Algebras [PDF]
Electronic Proceedings in Theoretical Computer Science, 2017 In this paper, W*-algebras are presented as canonical colimits of diagrams of matrix algebras and completely positive maps. In other words, matrix algebras are dense in W*-algebras.
Mathys Rennela +2 more
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Extremal problems for completely positive maps
International Journal of Mathematics and Mathematical Sciences, 1994 In this note, we study the faces of some convex subsets of CPc(A,B(ℋ))(the continuous completely positive linear maps from pro-C*-algebra A to B(ℋ)).
Mingze Yang
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Time inhomogeneous quantum dynamical maps
Scientific Reports, 2022 We discuss a wide class of time inhomogeneous quantum evolution which is represented by two-parameter family of completely positive trace-preserving maps. These dynamical maps are constructed as infinite series of jump processes.
Dariusz Chruściński
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Approximating quantum channels by completely positive maps with small Kraus rank [PDF]
QuantumWe study the problem of approximating a quantum channel by one with as few Kraus operators as possible (in the sense that, for any input state, the output states of the two channels should be close to one another).
Cécilia Lancien, Andreas Winter
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Bloch equations and completely positive maps [PDF]
Journal of Modern Optics, 2004 The phenomenological dissipation of the Bloch equations is reexamined in the context of completely positive maps. Such maps occur if the dissipation arises from a reduction of a unitary evolution of a system coupled to a reservoir. In such a case the reduced dynamics for the system alone will always yield completely positive maps of the density ...
Daffer, Sonja +2 more
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