Experimental Demonstration of Quantum-Flux-Latch-Based Circuits

We propose and discuss quantum-flux-latch (QFL) based circuits for adiabatic quantum-flux-parametron (AQFP) logic. The QFL-based XOR (QXOR) gate is a novel XOR gate. The circuit schematic of the QXOR is the same as that of a QFL, but QXORs operate on a different operation principle due to ac biasing. We designed and fabricated the QXOR and the half adder including a QXOR. We successfully demonstrated correct logic operations of these circuits at 4.2 K in the low-speed function test. Also, we estimated the energy dissipation of the QFL using a circuit simulator. The estimated energy dissipation was $sim$0.2 aJ/cycle.