Indexed on: 29 Feb '16Published on: 29 Feb '16Published in: Quantum Physics
Microwave photons are interesting qubits for quantum information processing. Here, we present the first scheme for the entanglement concentration on microwave photons, resorting to the cross-Kerr effect in circuit quantum electrodynamics (QED). Two superconducting transmission line resonators (TLRs) coupled to two transmon qubits with the N-type level structure induce the effective cross-Kerr effect for realizing the quantum nondemolition (QND) measurement on microwave photons in entanglement concentration. With this device, we present a two-qubit polarization parity QND detector on the photon states of the superconducting TLRs, which can be used to concentrate efficiently the non-maximally entangled states of microwave photons assisted by several linear microwave elements. This scheme may be useful for solid-state quantum information processing.