A Superconducting Optical Computer May Appear in the Near Future

Evan D. Walsh, Woochan Jung, Gil-Ho Lee +9 more

Josephson junctions are superconducting devices used as high-sensitivity magnetometers and voltage amplifiers as well as the basis of high-performance cryogenic computers and superconducting quantum computers. Although device performance can be degraded by the generation of quasiparticles formed from broken Cooper pairs, this phenomenon also opens opportunities to sensitively detect electromagnetic radiation. We demonstrate single near-infrared photon detection by coupling photons to the localized surface plasmons of a graphene-based Josephson junction. Using the photon-induced switching statistics of the current-biased device, we reveal the critical role of quasiparticles generated by the absorbed photon in the detection mechanism. The photon sensitivity will enable a high-speed, low-power optical interconnect for future superconducting computing architectures.

Yutaka Tabuchi

Frank K. Wilhelm, Kouichi Semba

M. I. Skolnik

Steady progress has been made in both theory and technology of superconductive electronics, but there has been little application to operational electronic systems. This paper, which was prepared for presentation at the 1976 Navy Summer Study on Superconductive Electronics, reviews those applications that might be of interest to radar. These applications include low-noise receivers, stable RF sources, MTI, synthetic aperture radar, and other areas of signal processing. Also included is a brief discussion of some of the potential problems associated with the use of such devices in a practical radar. Although there are areas of possible radar application of superconductive electronic devices, the burden of using cryogenics operationally as well as the availability of other competing electronic devices make it appear unlikely that superconducting electronics will find significant application in radar in the near future. (Author)

Chao Song, Jing Xin Cui, H. Wang +3 more

Medium-scale quantum devices that integrate about hundreds of physical qubits are likely to be developed in the near future. However, these devices will lack the resources for realizing quantum fault tolerance. Therefore, the main challenge of exploring the advantage of quantum computation is to minimize the impact of device and control imperfections without complete logical encoding. Quantum error mitigation is a solution satisfying the requirement. Here, we demonstrate an error mitigation protocol based on gate set tomography and quasi-probability decomposition. One- and two-qubit circuits are tested on a superconducting device, and computation errors are successfully suppressed. Because this protocol is universal for digital quantum computers and algorithms computing expected values, our results suggest that error mitigation can be an essential component of near-future quantum computation.

Arvind Mamgain, Siddhi Satish Khaire, Ujjawal Singhal +6 more