Implementing one-photon three-qubit quantum gates using spatial light modulators

摘要

Increasing the information-carrying capacity of a single photon may be achieved by utilizing multiple degreesnof freedom. We describe here an approach that utilizes two degrees of freedom to encode three qubits pernphoton: one in polarization and two in the spatial-parity symmetry of the transverse field. In this conception,na polarization-sensitive spatial light modulator corresponds to a three-qubit controlled-unitary gate with onencontrol qubit (polarization) and two target (spatial-parity-symmetry) qubits. We describe the construction ofncontrolled-NOT (CNOT), nn√nCNOT, controlled-PHASE, and Fredkin gates, and the preparation of one-photon, threequbitnGreenberger-Horne-Zeilinger (GHZ) and W states. This approach enables simple optical implementationsnof few-qubit tasks in quantum information processing.