Entangled coherent states can be prepared remotely by subtracting nonlocally a single photon from two quantum superpositions of coherent states, the so-called “Schrödinger’s cat” state. Such entanglement can further be distributed over longer distances by successive entanglement swapping operations using linear optics and photon-number resolving detectors. The aim of this paper is to evaluate the performance of this approach to quantum repeaters for long-distance quantum communications. Despite many attractive features at first sight, we show that, when using state-of-the-art photon counters and quantum memories, they do not achieve higher entanglement generation rates than repeaters based on single-photon entanglement. We discuss potential developments, which may take better advantage of the richness of entanglement based on continuous variables, including in particular efficient parity measurements.
© 2010 Optical Society of America
Original Manuscript: December 22, 2009
Manuscript Accepted: March 12, 2010
Published: May 4, 2010
Nicolas Sangouard, Christoph Simon, Nicolas Gisin, Julien Laurat, Rosa Tualle-Brouri, and Philippe Grangier, "Quantum repeaters with entangled coherent states," J. Opt. Soc. Am. B 27, A137-A145 (2010)