Accessible versus Holevo Information for a Binary Random Variable

Details Accessible versus Holevo Information for a Binary Random Variable Accessible versus Holevo Information for a Binary Random Variable

2006-03-30

arxiv.org/abs/quant-ph/0603278v4

Physics

Quantum Physics

ver 1, 6 pages, no figure; ver 2, 7 pages, no figure; ver 3, 11 pages, 3 figures

Scientific paper

The accessible information acc(E) of an ensemble E is the maximum mutual information between a random variable encoded into quantum states, and the probabilistic outcome of a quantum measurement of the encoding. Accessible information is extremely difficult to characterize analytically; even bounds on it are hard to place. The celebrated Holevo bound states that accessible information cannot exceed chi(E), the quantum mutual information between the random variable and its encoding. However, for general ensembles, the gap between the acc(E) and chi(E) may be arbitrarily large. We consider the special case of a binary random variable, which often serves as a stepping stone towards other results in information theory and communication complexity. We give explicit lower bounds on the the accessible information acc(E) of an ensemble E = {(p, rho_0), (1-p, rho_1)}, with 0 <= p <= 1, as functions of p and chi(E). The bounds are incomparable in the sense that they surpass each other in different parameter regimes. Our bounds arise by measuring the ensemble according to a complete orthogonal measurement that preserves the fidelity of the states rho_0,rho_1. As an intermediate step, therefore, we give new relations between the two quantities acc(E), chi(E) and the fidelity B(rho_0,rho_1).

Affiliated with

Also associated with

No associations

Rating

Accessible versus Holevo Information for a Binary Random Variable does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Accessible versus Holevo Information for a Binary Random Variable, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Accessible versus Holevo Information for a Binary Random Variable will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-141992