Scalable feedback stabilization of quantum light sources on a CMOS chip

Abstract

Silicon photonics could soon be used to create the vast numbers of physical qubits needed to achieve useful quantum information processing by leveraging mature complementary metal–oxide–semiconductor (CMOS) manufacturing to miniaturize optical devices for generating and manipulating quantum states of light. However, the development of practical silicon quantum-photonic integrated circuits faces challenges related to high sensitivity to process and temperature variations, free-carrier and self-heating nonlinearities, and thermal crosstalk. These issues have been partially addressed with bulky off-chip electronics, but this sacrifices many benefits of a chip-scale platform. Here we report an electronic–photonic quantum system-on-chip that consists of quantum-correlated photon-pair sources stabilized via on-chip feedback control circuits and is fabricated in a commercial 45-nm CMOS microelectronics foundry. We use non-invasive photocurrent sensing in a tunable microring cavity photon-pair source to actively lock it to a fixed-wavelength pump laser while operating in the quantum regime, enabling large-scale microring-based quantum systems. We also show that these sources maintain stable quantum properties and operate reliably in a practical setting with many adjacent photon-pair sources creating thermal disturbances on the same chip. Such dense integration of electronics and photonics enables implementation and control of quantum-photonic systems at the scale needed to achieve useful quantum information processing with CMOS-fabricated chips. An electronic–photonic quantum system-on-chip—fabricated in a 45-nm complementary metal–oxide–semiconductor microelectronics foundry—provides scalable control of microring resonator quantum photon-pair sources through the monolithic integration of silicon quantum photonics with complex control electronics on the same die.