Eur. Phys. J. D (2014) 68: 109
https://doi.org/10.1140/epjd/e2014-40656-y

Regular Article

Directly measuring the concurrence of atomic two-qubit states through the detection of cavity decay

¹ Key Laboratory of Opto-electronic Information Acquisition and Manipulation, Ministry of Education, School of Physics & Material Science, Anhui University, Hefei 230601, P.R. China
² School of Physics and Electrical Engineering, Anqing Normal University, Anqing 246011, P.R. China
³ School of Electronic information Engineering, Hefei Normal University, Hefei 230061, P.R. China

^a e-mail: zhangllhh@126.com
^b e-mail: mingyang@ahu.edu.cn

Received: 24 October 2013
Received in final form: 11 February 2014
Published online: 7 May 2014

Abstract

We present a scheme for directly measuring the concurrence of atomic two-qubit states (including pure states and mixed states) by detecting the photons leaking from the cavities where the atoms are located. We found that it is possible to encode the concurrence of two-atom entangled states in the photon detection results on the cavities. Cavity decay usually plays a passive role in quantum information processing, but in our scheme the decay of cavity mode plays a constructive role, and the state detection for trapped atoms were replaced by the photon detection. Our scheme is more implementable and may be feasible within the current technology.