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

Quantum information processing (QIP) can provide exponential speed-up 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.