Universal Photonic Quantum Gate by Cooper-pair-based Optical Nonlinearity

Quantum information processing (QIP) can provide exponential speedup of various computational algorithms physically proven data security. Many realizations of QIP employ photons as qubits in applications such as cryptography [1], computing [2], [3], and teleportation [4]. Despite their many uses, implementing photon-based quantum gates is extremely challenging due to the very weak photon-photon interaction in practical materials [5]. Lately, a field of superconducting optoelectronics emerged, investigating light-matter interaction in semiconductor-superconductor structures [6], [7]. Such interactions were shown to result in novel processes based on strongly-enhanced optical nonlinearities, including spontaneous two-photon emission [8] and two-photon gain [9], enabling various aspects of QIP such as full Bell state analysis [10] and entangled-photon generation [11]. Nevertheless, a complete infrastructure for superconductor-based photonic quantum information processing requires quantum gate schemes, which have not been studied so far.