About the project
Today's quantum computers need a dedicated microwave source per qubit, a wiring bottleneck limiting scale-up. This project builds an on-chip superconducting device where a single microwave frequency source drives an entire qubit array at distinct frequencies up to the millimetre-wave range, using space-time-modulated Josephson junctions for nonreciprocal multiplexing.
Superconducting quantum processors are limited not just by qubit coherence but by wiring: each qubit typically needs its own microwave control line, and this overhead grows rapidly as processors scale toward hundreds or thousands of qubits. This project addresses that bottleneck by developing a fundamentally new class of on-chip control hardware: a nonreciprocal, space-time-modulated superconducting frequency multiplier that converts a single drive into a full comb of directionally isolated tones spanning up to millimetre-wave frequencies, with each tone addressing a different qubit, removing the need for a dedicated high-frequency source per qubit.
Building on theoretical and simulation work recently published by the supervisory team (IEEE Transactions on Antennas and Propagation), you'll take this device from simulation to hardware: developing the circuit and Hamiltonian models, designing and fabricating superconducting thin-film prototypes, and integrating them with a small array of flux-tunable transmon qubits. You'll characterise harmonic-comb generation, nonreciprocal isolation, and the resulting suppression of Purcell decay and qubit-qubit crosstalk at millikelvin temperatures, establishing whether this architecture can genuinely reduce the wiring burden of scalable quantum computing.
