Optimal atomic entanglement concentration using coherent-state input–output process in low-Q cavity quantum electrodynamics system
Cong Cao, Chuan Xi Wang, Lingyan He, Xin Tong, Ming Lei, Ru Zhang · Journal of the Optical Society of America B · 2013
This paper presents an optimal entanglement concentration protocol (ECP) for entangled solid-state systems, using the coherent-state input–output process working in the low-Q cavity quantum electrodynamics regime. The solid-state system can be described as a three-level atom confined in a one-side optical microcavity. Using the ancillary coherent optical pulse to perform the cavity input–output process, different state-dependent phase shifts of the output coherent state can be discriminated by homodyne detection, and a less-entangled atomic pair can be concentrated to maximally entangled state in a certain probability between two remote parties nonlocally. By repeating the concentration process, the remote parties can further obtain a higher success probability. Compared with conventional ECPs, only one pair of less-entangled atoms is needed in the proposed protocol, and the coherent-state input–output process is working in a low-Q cavity in the atom–cavity intermediate coupling region. With feasible technologies, this protocol may be widely used in quantum repeaters and long-distance quantum communication.