Optimal Approximation of Nonphysical Maps via Maximum Likelihood Estimation

Bužek, Vladimír; Ziman, Mário; Plesch, Martin

doi:10.1117/3.793309.ch25

Book: Advances in Information Optics and Photonics

Editor(s): Ari T. Friberg; René Dändliker

Author(s): Vladimír Bužek, Mário Ziman, Martin Plesch

Published: 2008

https://doi.org/10.1117/3.793309.ch25

Abstract

Any quantum dynamics, i.e., the process that is described by a completely positive (CP) map of a quantum-mechanical system, can be probed in two different ways. Either we use a single entangled state of a bipartite system, or we use a collection of linearly independent single-particle test states (forming a basis of the vector space of all Hermitian operators). Given the fragility of entangled states, in this chapter we will focus our attention on the process reconstruction using only single-particle states.