Workshop on QUANTUM INFORMATION PROCESSING AND QUANTUM COMMUNICATIONS
Quantum Information Processing and Quantum Communications
Beyond the Heisenberg uncertainty
|aula 202 - Mercoledì 5 maggio ore 11.00|
SHIH and M. D’ANGELO, Quantum Optics Laboratory,
University of Maryland, Baltimore County,
Baltimore, MD 21250
Yanhua Shih received his B.S. degree from Northwestern University, China
in 1981 and his Ph.D. in Physics from the University of Maryland in 1987.
He joined the faculty of the Department of Physics and started the Quantum
Optics Laboratory at the University of Maryland in 1989. He is currently
|Quantum entanglement is one of the most surprising consequences
of quantum mechanics. Based on EPR‚s criteria, the presence of the
d-functions d(p1+p2) and d(x1-x2) in the idealized entangled two-particle
system, seems to represent a violation of the uncertainty principle. It
is indeed true, from a statistical point of view, that correlation measurements
realized on two independent particles must obey the inequalities:
D(p1+p2) > Max(Dp1, Dp2) and D(x1-x2) > Max(Dx1, Dx2).
The apparent contradiction between these classical inequalities and the EPR inequalities:
D(p1+p2) < min(Dp1, Dp2) and D(x1-x2) < min(Dx1, Dx2) has deeply troubled EPR and many other physicists. Our recent experiments have demonstrated that entangled two-photon systems satisfy the EPR inequalities. These experimental demonstrations also highlighted a number of novel practical protocols for high-precision timing and positioning applications. The accuracy in these measurements could overcome, in principle, the limitations imposed by the uncertainty principle. However, we show that this is not a violation of the uncertainty principle.