40 Gbit/s operation of superconductive single flux quantum digital integrated circuit with optical data input

A superconductive single flux quantum (SFQ) digital integrated circuit with an optical data input has been demonstrated at the system level of 40 Gbit/s for the first time. A uni travelling carrier photodiode (UTC-PD) and an SFQ circuit chip, on which 40 Gbit/s I/O interfaces were integrated, were packaged on a cold stage (4 6 K) of a cryocooler system. The UTC-PD s output was connected to an input port of the SFQ circuit with a Cu coaxial cable. From room temperature, a 40 GHz clock was supplied to the SFQ circuit while 40 Gbit/s optical data were supplied to the UTC-PD. The SFQ circuit operated correctly with the optical 40 Gbit/s data. The measured bit error rate was less than 10^-13 for 1.2 mW optical PRBS 7 input at 40 Gbit/s.