Separable Measurement Estimation of Density Matrices and its Fidelity Gap with Collective Protocols

E. Bagan, M. A. Ballester, R. D. Gill, R. Muñoz-Tapia, and O. Romero-Isart
Phys. Rev. Lett. 97, 130501 – Published 25 September 2006

Abstract

We show that there exists a gap between the performance of separable and collective measurements in the qubit mixed-state estimation that persists in the large sample limit. We characterize the gap with sharp asymptotic bounds on mean fidelity. We present an adaptive protocol that attains the separable measurement bound. This protocol uses von Neumann measurements and can be easily implemented with current technology.

  • Received 7 April 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.130501

©2006 American Physical Society

Authors & Affiliations

E. Bagan1, M. A. Ballester2, R. D. Gill3,4, R. Muñoz-Tapia1, and O. Romero-Isart1

  • 1Grup de Física Teòrica & IFAE, Facultat de Ciències, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra Barcelona, Spain
  • 2Centrum voor Wiskunde en Informatica, Kruislaan 413, 1098 SJ Amsterdam, The Netherlands
  • 3Department of Mathematics, University of Leiden, Box 9512, 2300 RA Leiden, The Netherlands
  • 4EURANDOM, Post Office Box 513-5600 MB Eindhoven, The Netherlands

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 97, Iss. 13 — 29 September 2006

Reuse & Permissions
Access Options

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Letters

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×