A photonic which-path entangler based on longitudinal cavity-qubit coupling

Abstract

We show that a modulated longitudinal cavity-qubit coupling can be used to control the path taken by a multiphoton coherent-state wavepacket conditioned on the state of a qubit, resulting in a qubit-which-path (QWP) entangled state. QWP states can generate long-range multipartite entanglement using strategies for interfacing discrete- and continuous-variable degrees-of-freedom. Using the approach presented here, entanglement can be distributed in a quantum network without the need for single-photon sources or detectors.