Nondestructive Rydberg parity meter and its applications

Parity meters, utilized to distinguish bipartite quantum states with even or odd parity, have many applications in quantum information processing. We propose a potentially practical scheme to construct the nondestructive Rydberg parity meter (NRPM) in ground-state subspace using Rydberg atoms. Based on the proposed NRPM, the parity of the qubit atoms could be known in a deterministic and nondestructive way, implying that the output state of the NRPM can be further used in the rest of the process for quantum information tasks. In addition, we study the applications of the proposed NRPM in entangled state fusion, entangled state analysis, and quantum teleportation, as well as quantum logic gate in a decoherence-free subspace regarding collective-dephasing errors. We analyze the performance of the NRPM under the influence of decoherence and consider more general situations for the feasibility of the scheme.