Over the past decade, significant progress in quantum technologies has been made, and hence, engineering of these systems has become an important research area. Many researchers have become interested in studying ways in which classical integrated circuits can be used to complement quantum mechanical systems, enabling more compact, performant, and/or extensible systems than would be otherwise feasible. In this article - written by a consortium of early contributors to the field - we provide a review of some of the early integrated circuits for the quantum information sciences. Complementary metal - oxide semiconductor (CMOS) and bipolar CMOS (BiCMOS) integrated circuits for nuclear magnetic resonance, nitrogen-vacancy-based magnetometry, trapped-ion-based quantum computing, superconductor-based quantum computing, and quantum-dot-based quantum computing are described. In each case, the basic technological requirements are presented before describing proof-of-concept integrated circuits. We conclude by summarizing some of the many open research areas in the quantum information sciences for CMOS designers.

Cryogenic solid-state quantum processors require classical control and readout electronics; to achieve compactness and scalability, cryogenic integrated circuits have been recently proposed for this goal. Circulators are widely used in readout circuits, however they are typically discrete bulky devices, thus preventing miniaturization. To address this issue, we propose a fully integrated 40-nm CMOS 6.5-GHz circulator operating from 300 K to 4.2 K. At 300 K, it achieves a 2.2-dB insertion loss, an 18-dB isolation, and a 2.4-dB noise figure over the 1-dB bandwidth from 5.6 GHz to 7.4 GHz, with a core power of only 2.5 mW. This improves to 2.1 mW core power at 4.2 K, while showing 1.3-dB insertion loss and 17-dB isolation over the 1-dB bandwidth from 5.8 GHz to 7.6 GHz. The circuit achieves a record-low core power and a 1.6× wider fractional bandwidth than the state-of-the-art, thus allowing its use for multiple channels in power-constrained cryogenic refrigerators. These advances are enabled by a fully-passive architecture based on LC all-pass filters, allowing the use of a lower clock frequency than in prior art.

SPAD (single-photon avalanche diode) arrays are single-photon sensors, which enable photon counting and unparalleled time-resolved imaging. In this paper, we will detail the architecture and characteristics of three representative SPAD arrays, implemented in standard CMOS technologies and targeted to a range of applications such as biophotonics, basic sciences, and engineering. Two sensors feature a high-performance pixel and enable time-gated and TCSPC operation, respectively. The third sensor is a line array whose pixels are coupled on a one-To-one basis with an FPGA for flexible data acquisition and processing.