DIMACS TR: 2002-55
Local vs. joint measurements for the entanglement of assistance
Authors: T. Laustsen, F. Verstraete, and S. J. van Enk
ABSTRACT
We consider a variant of the entanglement of assistance, as
independently introduced by D.P. DiVincenzo {\em et al.} ({\tt
quant-ph/9803033}) and O. Cohen (Phys. Rev. Lett. {\bf 80}, 2493
(1998)). Instead of considering three-party states in which one of the
parties, the assistant, performs a measurement such that the remaining
two parties are left with on average as much entanglement as possible,
we consider four-party states where two parties play the role of
assistants. We answer several questions that arise naturally in this
scenario, such as (i) how much more entanglement can be produced when
the assistants are allowed to perform joint measurements, (ii) for
what type of states are local measurements sufficient, (iii) is it
necessary for the second assistant to know the measurement outcome of
the first, and (iv) are projective measurements sufficient or are more
general POVMs needed?
Paper Available at:
ftp://dimacs.rutgers.edu/pub/dimacs/TechnicalReports/TechReports/2002/2002-55.ps.gz
DIMACS Home Page