Design and Implementation of RSFQ Microwave Choppers for the Superconducting Quantum-Computing System


IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.4   pp.458-462
Publication Date: 2010/04/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.458
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Frontiers of Superconductive Electronics)
Category: Digital Applications
SFQ,  quantum bit,  microwave chopper,  superconducting circuits,  

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We have been studying a superconducting quantum-computing system where superconducting qubits are controlled and read out by rapid single-flux- quantum (RSFQ) circuits. In this study, we designed and fabricated an RSFQ microwave chopper, which turns on and off an externally applied microwave to control qubit states with the time resolution of sub-nanosecond. The chopper is implemented in a microwave module and mounted in a dilution refrigerator. We tested the microwave chopper at 4.2 K. The amplitude of the output microwave was approximately 100 µV which is much larger than that of previously designed chopper. We also confirmed that the irradiation time can be controlled by RSFQ control circuits.