On-chip microwave generator for manipulation of superconductive quantum bits

A new on-chip microwave generator for manipulating superconductive quantum bits (qubits) have been proposed. To perform practical quantum computation, on-chip microwave generators, which can be controlled by single flux quantum (SFQ) circuits, are desirable because multiple qubits can be driven simultaneously with high accuracy by an SFQ control circuit and the number of wires between qubits and room-temperature electronics can be reduced. The proposed on-chip microwave generator is composed of an SFQ clock generator, which generates a periodic SFQ pulse train, and a band-pass filter. A sinusoidal microwave can be obtained by filtering an output of the SFQ clock generator. Simulation results indicate that the generated microwave has a sharp spectrum, which can be chopped by controlling the SFQ clock generator. Moreover, a phase of the generated microwave can be accurately controlled by adding a phase control circuit, which is composed of cascaded toggle flip-flops, between the SFQ clock generator and the filter. The results indicate that we can perform fast and accurate quantum gate operations using the proposed on-chip microwave generator. (c) 2006 Elsevier B.V. All rights reserved.