Superconducting Electronics: Toward an Ultrafast Computer

Romain Collot, Pascal Febvre

Marc Currie

Roman Adam

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.

Chia-Chi Wang, Marc Currie, T.Y. Hsiang

An ultrafast optical interface between superconducting and room-temperature electronics is proposed to take full advantage of high-speed superconducting circuits. We report on the computed and experimental studies of an optical receiving and modulating system that is compatible in processing with the prevailing integrated-superconducting-circuit technology. Planar interdigitated Nb/Si/Nb metal-semiconductor-metal (MSM) photodiodes are demonstrated as optical receivers with resolvable bit-rate as high as 38 Gb/s, and the response of MSM diode was shaped to be a single-flux-quantum pulse to drive Josephson-junction-based circuits. A similar interdigitated structure on a silicon waveguide is proposed to be an ultrafast light-intensity modulator, with its operation based on carrier-density modulation of the optical index of refraction. This field-effect device has insignificant power dissipation, in addition to high speed. A sample modulator with 5-V bias is shown to have a modulation depth of 40% and a bandwidth over 70 GHz.>

Andrea M. Herr