Quantum–classical interface based on single flux quantum digital logic
R McDermott, M G Vavilov, B L T Plourde, F K Wilhelm, P J Liebermann, O A Mukhanov, T A Ohki · Quantum Science and Technology · 2017
Abstract We describe an approach to the integrated control and measurement of a large-scale superconducting multiqubit array comprising up to 10 8 physical qubits using a proximal coprocessor based on the Single Flux Quantum (SFQ) digital logic family. Coherent control is realized by irradiating the qubits directly with classical bitstreams derived from optimal control theory. Qubit measurement is performed by a Josephson photon counter, which provides access to the classical result of projective quantum measurement at the millikelvin stage. We analyze the power budget and physical footprint of the SFQ coprocessor and discuss challenges and opportunities associated with this approach.