Quantum trajectories for the realistic measurement of a solid-state charge qubit

Neil P. Oxtoby, P. Warszawski, H. M. Wiseman, He-Bi Sun, and R. E. S. Polkinghorne
Phys. Rev. B 71, 165317 – Published 19 April 2005

Abstract

We present a new model for the continuous measurement of a coupled quantum dot charge qubit. We model the effects of a realistic measurement, namely adding noise to, and filtering, the current through the detector. This is achieved by embedding the detector in an equivalent circuit for measurement. Our aim is to describe the evolution of the qubit state conditioned on the macroscopic output of the external circuit. We achieve this by generalizing a recently developed quantum trajectory theory for realistic photodetectors [P. Warszawski, H. M. Wiseman, and H. Mabuchi, Phys. Rev. A 65, 023802 (2002)] to treat solid-state detectors. This yields stochastic equations whose (numerical) solutions are the “realistic quantum trajectories” of the conditioned qubit state. We derive our general theory in the context of a low transparency quantum point contact. Areas of application for our theory and its relation to previous work are discussed.

  • Figure
  • Figure
  • Received 12 January 2004

DOI:https://doi.org/10.1103/PhysRevB.71.165317

©2005 American Physical Society

Authors & Affiliations

Neil P. Oxtoby1,2,*, P. Warszawski1, H. M. Wiseman1,†, He-Bi Sun1,2, and R. E. S. Polkinghorne2

  • 1Centre for Quantum Computer Technology, Centre for Quantum Dynamics, School of Science, Griffith University, Nathan QLD 4111, Australia
  • 2Centre for Quantum Computer Technology, School of Physical Sciences, The University of Queensland, St. Lucia QLD 4072, Australia

  • *Electronic address: n.oxtoby@griffith.edu.au
  • Electronic address: h.wiseman@griffith.edu.au

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 71, Iss. 16 — 15 April 2005

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 B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×