For multiqubit density operators in a suitable tensorial basis, we show that a number of nonunitary operations used in the detection and synthesis of entanglement are classifiable as reflection symmetries, i.e., orientation changing rotations. While one-qubit reflections correspond to antiunitary symmetries, as is known, for example, from the partial transposition criterion, reflections on the joint density of two or more qubits are not accounted for by the Wigner theorem and are well-posed only for sufficiently mixed states. One example of such nonlocal reflections is the unconditional NOT operation on a multiparty density, i.e., an operation yeilding another density and such that the sum of the two is the identity operator. This nonphysical operation is admissible only for sufficiently mixed states.

Reflection symmetries for multiqubit densities

Altafini, Claudio;
2006-01-01

Abstract

For multiqubit density operators in a suitable tensorial basis, we show that a number of nonunitary operations used in the detection and synthesis of entanglement are classifiable as reflection symmetries, i.e., orientation changing rotations. While one-qubit reflections correspond to antiunitary symmetries, as is known, for example, from the partial transposition criterion, reflections on the joint density of two or more qubits are not accounted for by the Wigner theorem and are well-posed only for sufficiently mixed states. One example of such nonlocal reflections is the unconditional NOT operation on a multiparty density, i.e., an operation yeilding another density and such that the sum of the two is the identity operator. This nonphysical operation is admissible only for sufficiently mixed states.
2006
47
Altafini, Claudio; Havel, T. F.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/30272
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 4
  • ???jsp.display-item.citation.isi??? 3
social impact