66

Getting almost all the bits from a quantum random access code

Main:12 Pages
1 Figures
Bibliography:2 Pages
Abstract

A quantum random access code (QRAC) is a map xρxx\mapsto\rho_x that encodes nn-bit strings xx into mm-qubit quantum states ρx\rho_x, in a way that allows us to recover any one bit of xx with success probability p\geq p. The measurement on ρx\rho_x that is used to recover, say, x1x_1 may destroy all the information about the other bits; this is in fact what happens in the well-known QRAC that encodes n=2n=2 bits into m=1m=1 qubits. Does this generalize to large nn, i.e., could there exist QRACs that are so "obfuscated" that one cannot get much more than one bit out of them? Here we show that this is not the case: for every QRAC there exists a measurement that (with high probability) recovers the full nn-bit string xx up to small Hamming distance, even for the worst-case xx.

View on arXiv
Comments on this paper