Linear transformations of quantum states
2008 (English)In: Annals of Physics, ISSN 0003-4916, E-ISSN 1096-035X, Vol. 323, no 4, 893-906 p.Article in journal (Refereed) Published
This paper considers the most general linear transformation of a quantum state. We enumerate the conditions necessary to retain a physical interpretation of the transformed state: hermiticity, normalization and complete positivity. We show that these can be formulated in terms of an associated transformation introduced by Choi in 1975. We extend his treatment and display the mathematical argumentation in a manner closer to that used in traditional quantum physics. We contend that our approach displays the implications of the physical requirements in a simple and intuitive way. In addition, defining an arbitrary vector, we may derive a probability distribution over the spectrum of the associated transformation. This fixes the average of the eigenvalue independently of the vector chosen. The formal results are illustrated by a couple of examples.
Place, publisher, year, edition, pages
2008. Vol. 323, no 4, 893-906 p.
linear transformations, complete positivity, Kraus sum
IdentifiersURN: urn:nbn:se:kth:diva-33160DOI: 10.1016/j.aop.2007.06.001ISI: 000255216300007ScopusID: 2-s2.0-40649118507OAI: oai:DiVA.org:kth-33160DiVA: diva2:413670
QC 201104292011-04-292011-04-292011-04-29Bibliographically approved