DP Seminar

[Luca Ferialdi]

Department of Physics - Miramare - University of Trieste

Wednesday 27 April 2011 - 3.00 pm
Room 204 (2nd floor LB)

Dr. Stefano Olivares
(University of Trieste)

Title: 
The birth of entanglement in the interference of Gaussian states:
the role of the fidelity

Abstract:
At the hearth of quantum technology there is entanglement. Indeed,
during the last two decades much attention has been devoted to the
generation and the characterization of entanglement in bipartite and
multi-partite systems. In the realm of continuous variables, attention
has been focused to Gaussian states. Among the the possible mechanisms
to generate Gaussian entanglement, the one consisting in the mixing of
squeezed states at a beam splitter is of special interest in view of
its feasibility. In this seminar we briefly review the interference of
single photons at a beam splitter and the basic properties of the
Gaussian states and operations. We then address the interaction of two
Gaussian states interfering at a beam splitter and analyze the
correlations exhibited by the resulting bipartite system. We show that
nonlocal correlations (entanglement) arise if and only if the fidelity
between the two input Gaussian states falls under a threshold value
depending only on their purities and on the transmissivity of the beam
splitter. Our result clarifies the role of squeezing as a prerequisite
for entanglement and provides a tool to optimize the generation of
entanglement by passive devices.