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arXiv:1803.09541

Schmidt decomposition of mixed-pure states for (d,infinity ) systems and some applications

Roman Gielerak

Published Mar 26, 2018• 2 citations
arXivHTMLPDF

Abstract

Summary. A simple derivation of finite Schmidt decomposition of pure states describing finite dimensional systems interacting with the infinite dimensional ones is presented. In particular, maximally entangled pure states in such systems are being characterized. The concept of mixed-pure states has been introduced and some criterions for checking separability and entanglement of them are presented .The notion of LOCC equivalence and LOCC semi-order on the space of pure states of systems analyzed has been adopted suitably. In particular a Nielsen -like theorem has been extended to the pure (d, infinity )- states case. The notion of spin-orbit entanglement in the context of atomic physics is being discussed from a mathematical perspective. Keywords: quantum entanglement, Schmidt decomposition, mixed-pure states, LOCC semi-order, spin-orbit entanglement

DOI
10.48550/arxiv.1803.09541

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Summary. A simple derivation of finite Schmidt decomposition of pure states describing finite dimensional systems interacting with the infinite dimensional ones is presented. In particular, maximally entangled pure states in such systems are being characterized. The concept of mixed-pure states has been introduced and some criterions for checking separability and entanglement of them are presented .The notion of LOCC equivalence and LOCC semi-order on the space of pure states of systems analyzed has been adopted suitably. In particular a Nielsen -like theorem has been extended to the pure (d, infinity )- states case. The notion of spin-orbit entanglement in the context of atomic physics is being discussed from a mathematical perspective. Keywords: quantum entanglement, Schmidt decomposition, mixed-pure states, LOCC semi-order, spin-orbit entanglement
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Abstract We present Schmidt decomposition formulas for mutually orthogonal two-qubit pure states and classify orthonormal sets according to their entanglement structure. We begin by presenting explicit formulas for the Schmidt decomposition of arbitrary two-qubit pure states. Building on this, we construct and analyze all possible configurations of two mutually orthogonal pure states, providing corresponding Schmidt decomposition expressions for each case. For orthonormal sets of three and four states, we derive explicit formulas for selected representative types and discuss the difficulties in obtaining closed-form expressions for more general cases. In particular, we focus on special classes of orthonormal bases that include one or two maximally entangled states. Finally, we prove that no orthonormal basis can contain three product states and one entangled state, revealing a structural constraint that restricts the composition of entangled orthonormal sets.