Investigation of High-Tc Single Flux Quantum Logic Gates

Kazuo SAITOH  Hiroyuki FUKE  

IEICE TRANSACTIONS on Electronics   Vol.E80-C   No.10   pp.1233-1239
Publication Date: 1997/10/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Issue on Basic Properties and Applications of Superconductive Electron Devices)
single flux quantum (SFQ),  rf-SQUID,  dc SQUID,  focused ion beam,  Josephson junction,  superconducting weak link,  

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Logic operations in principle have been demonstrated based on the planar high-Tc Superconducting QUantum Interference Device (SQUID). Two kinds of logic gates were produced by using the focused ion beam (FIB) superconducting weak links fabricated in NdBa2Cu3O7-δ (NBCO) thin films. Logic gates investigated in this paper are (1) an rf-SQUID based logic gate which utilizes threshold characteristics, and (2) a dc-SQUID based logic gate which is an elementary gate of RSFQ circuits. Elementary logic operation such as (1) AND/OR logic and (2) SET-RESET flip-flop operation were successfully obtained in the logic gates. In addition to the present experimental results, some problems and future prospects are also discussed.