7,931 research outputs found
Continuous-variable teleportation: a new look
In contrast to discrete-variable teleportation, a quantum state is
imperfectly transferred from a sender to a remote receiver in a
continuous-variable setting. We recall the ingenious scheme proposed by
Braunstein and Kimble for teleporting a one-mode state of the quantum radiation
field. By analyzing this protocol, we have previously proven the factorization
of the characteristic function of the output state. This indicates that
teleportation is a noisy process that alters, to some extent, the input state.
Teleportation with a two-mode Gaussian EPR state can be described in terms of
the superposition of a distorting field with the input one. Here we analyze the
one-mode Gaussian distorting-field state. Some of its most important properties
are determined by the statistics of a positive EPR operator in the two-mode
Gaussian resource state. We finally examine the fidelity of teleportation of a
coherent state when using an arbitrary resource state.Comment: Contribution to the special issue of Romanian Journal of Physics
dedicated to the centenary of Serban Titeica (1908-1985), the founder of the
school of theoretical physics in Romani
Optimal purifications and fidelity for displaced thermal states
We evaluate the Uhlmann fidelity between two one-mode displaced thermal
states as the maximal probability transition between appropriate purifications
of the given states. The optimal purifications defining the fidelity are proved
to be two-mode displaced Gaussian states.Comment: published versio
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