0208080v2

related topics
{states, state, optimal}
{cos, sin, state}
{state, phys, rev}
{state, states, entangled}
{phase, path, phys}
{spin, pulse, spins}
{level, atom, field}
{observables, space, algebra}

On the Phase Covariant Quantum Cloning

V. Karimipour, A. T. Rezakhani

abstract: It is known that in phase covariant quantum cloning the equatorial states on the Bloch sphere can be cloned with a fidelity higher than the optimal bound established for universal quantum cloning. We generalize this concept to include other states on the Bloch sphere with a definite $z$ component of spin. It is shown that once we know the $z$ component, we can always clone a state with a fidelity higher than the universal value and that of equatorial states. We also make a detailed study of the entanglement properties of the output copies and show that the equatorial states are the only states which give rise to separable density matrix for the outputs.

oai_identifier:
oai:arXiv.org:quant-ph/0208080
categories:
quant-ph
comments:
Revtex4, 6 pages, 5 eps figures
doi:
10.1103/PhysRevA.66.052111
arxiv_id:
quant-ph/0208080
journal_ref:
Phys. Rev. A 66, 052111 (2002)
created:
2002-08-13
updated:
2002-09-07

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