Abstract
We propose efficient schemes of direct concurrence measurement for two-qubit spin and photon-polarization entangled states via the interaction between single-photon pulses and nitrogen-vacancy (NV) centers in diamond embedded in optical microcavities. For different entangled-state types, diversified quantum devices and operations are designed accordingly. The initial unknown entangled states are possessed by two spatially separated participants, and nonlocal spin (polarization) entanglement can be measured with the aid of detection probabilities of photon (NV center) states. This non-demolition entanglement measurement manner makes initial entangled particle-pair avoid complete annihilation but evolve into corresponding maximally entangled states. Moreover, joint inter-qubit operation or global qubit readout is not required for the presented schemes and the final analyses inform favorable performance under the current parameters conditions in laboratory. The unique advantages of spin qubits assure our schemes wide potential applications in spin-based solid quantum information and computation.
Highlights
We propose efficient schemes of direct concurrence measurement for two-qubit spin and photonpolarization entangled states via the interaction between single-photon pulses and nitrogen-vacancy (NV) centers in diamond embedded in optical microcavities
A number of theoretical and experimental schemes have been presented to direct measurement of concurrence for two-qubit entangled states[13,14,15,16,17], including pure states and mixed states
We present several schemes of directly measuring concurrence for two-qubit nonlocal entangled states, including two-qubit pure states and mixed states
Summary
Elements and atomic entangled states with cavity quantum electrodynamics system[18,19]. Recent researches confirm that electron spin states in diamond nitrogen-vacancy (NV) center have a long lifetime even at room temperature and can be manipulated and detected by microwave or optical field[21,22]. These unique characteristics make the NV center one of the most potential carrier of quantum information[23,24,25,26,27,28,29]. We analyze the influence of imprecise operating process and less-than-ideal parameters on our schemes
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