Hyper-parallel nonlocal CNOT operation assisted by quantum-dot spin in a double-sided optical microcavity

Abstract

Implementation of controlled-NOT (CNOT) operation between different nodes in a quantum communication network nonlocally plays an important role in distributed quantum computation. We present a protocol for implementation of hyper-parallel nonlocal CNOT operation via hyperentangled photons simultaneously entangled in spatial-mode and polarization degrees of freedom (DOFs) assisted by quantum-dot spin in a double-sided optical microcavity. The agent Alice lets photons traverse the double-sided optical microcavity sequentially and applies single-qubit measurements on the electron and the hyperentangled photon. The agent Bob first performs corresponding unitary operations according to Alice’s measurement results on his hyperentangled photon, and then lets photons traverse the double-sided optical microcavity sequentially and performs the single-qubit measurements on the electron and the hyperentangled photon. The hyper-parallel nonlocal CNOT operation can be implemented simultaneously in spatial-mode and polarization DOFs if Alice performs single-qubit operations in accordance with Bob’s measurement results. The protocol has the advantage of having high channel capacity for long-distance quantum communication by using a hyperentangled state as the quantum channel.