Tomography and Entanglement in Coupled Josephson Junction Qubits

Niels Grønbech-Jensen, Jeffrey E. Marchese, Matteo Cirillo, and James A. Blackburn
Phys. Rev. Lett. 105, 010501 – Published 29 June 2010

Abstract

We provide an alternative interpretation of experimental results that were represented as demonstrating entanglement between two macroscopic quantum Josephson oscillators. We model the experimental system using the well-established classical equivalent circuit of a resistively and capacitively shunted Josephson junction. Simulation results are used to generate the corresponding density matrix which shows features quite similar to the previously published matrix generated from experimental data. Since our data are generated by a classical model, we therefore submit that state tomography cannot be used to determine absolutely whether or not quantum entanglement has taken place. Analytical arguments are given for why the classical analysis provides an adequate explanation of the experimental results.

  • Figure
  • Figure
  • Received 1 May 2009

DOI:https://doi.org/10.1103/PhysRevLett.105.010501

©2010 American Physical Society

Authors & Affiliations

Niels Grønbech-Jensen1, Jeffrey E. Marchese1, Matteo Cirillo2, and James A. Blackburn3

  • 1Department of Applied Science, University of California, Davis, California 95616, USA
  • 2Dipartimento di Fisica and MINAS-Lab, Università di Roma “Tor Vergata”, I-00133 Roma, Italy
  • 3Department of Physics & Computer Science, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 105, Iss. 1 — 2 July 2010

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

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
×