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Phys. Rev. A 73, 042302 (2006) [9 pages]

Quantum walk on the line: Entanglement and nonlocal initial conditions

G. Abal, R. Siri, A. Romanelli, and R. Donangelo
Instituto de Física, Universidad de la República, C.C. 30, C.P. 11000, Montevideo, Uruguay
Received 29 July 2005; revised 28 November 2005; published 4 April 2006

The conditional shift in the evolution operator of a quantum walk generates entanglement between the coin and position degrees of freedom. This entanglement can be quantified by the von Neumman entropy of the reduced density operator (entropy of entanglement). We show analytically that for a Hadamard walk with local initial conditions the asymptotic entanglement is 0.872 for all initial coin states. When nonlocal initial conditions are considered, the asymptotic entanglement varies smoothly between almost complete entanglement and no entanglement (product state). An exact expression for the asymptotic (long-time) entanglement is obtained for initial conditions in the position subspace spanned by |±1>.

©2006 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.73.042302
DOI: 10.1103/PhysRevA.73.042302
PACS: 03.67.Mn; 89.70.+c; 89.75.Hc
  • 03.67.Mn
    Quantum entanglement production, characterization, and manipulation
  • 89.70.+c
    Information theory and communication theory
  • 89.75.Hc
    Networks and genealogical trees
  • YEAR: 2006
KEYWORDS: quantum entanglement, entropy, information theory, mathematical operators

See Also

Erratum: Quantum walk on the line: Entanglement and non-local initial conditions [Phys. Rev. A 73, 042302 (2006)]
G. Abal, R. Siri, A. Romanelli et al.
Phys. Rev. A 73, 069905 (E) (2006)

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Erratum

  1. Erratum: Quantum walk on the line: Entanglement and non-local initial conditions [Phys. Rev. A 73, 042302 (2006)]
    G. Abal, R. Siri, A. Romanelli et al.
    Phys. Rev. A 73, 069905 (E) (2006)


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