Principles of superconducting single-flux-quantum digital electronics

Quentin Herr

Matthew J. Beck

Andrea M. Herr

Roman Sobolewski

The basic concepts of the ultrafast optoelectronic interface for superconducting digital electronics are presented. Several implementations of both the input optical-to-electrical and the output electrical-to-optical transducers are discussed. As an example, an optoelectronic telecommunication router is used that is capable of switching signals at a >100 Gbit s −1 rate on a single wavelength. We demonstrate that superconducting optoelectronics emerges as the ultimate solution to the ultrafast input/output (I/O) interface of single-flux-quantum (SFQ)-based, superconducting digital electronics.

Hisao Hayakawa

Yerzhan Mustafa, Selçuk Köse

Interface circuits are the key components that enable the hybrid integration of superconductor and semiconductor digital electronics. The design requirements of superconductor-semiconductor interface circuits vary depending on the application, such as high-performance classical computing, superconducting quantum computing, and digital signal processing. In this survey, various interface circuits are categorized based on the working principle and structure. The superconducting output drivers are explored, which are capable of converting and amplifying, e.g., single flux quantum (SFQ) voltage pulses, to voltage levels that semiconductor circuits can process. Several trade-offs between circuit- and system-level design parameters are examined. Accordingly, parameters such as the data rate, output voltage, power dissipation, layout area, thermal/heat load of cryogenic cables, and bit-error rate are considered.