About the project
Every superconducting quantum computer's readout chain relies on bulky, magnetic ferrite circulators that block noise from reaching qubits, but can't be miniaturised or scaled. This project designs, fabricates, and tests a reconfigurable, on-chip, magnet-free circulator using space-time-modulated Josephson junctions, programmable in real time for next-generation AI-driven quantum control systems.
Reading out a superconducting qubit without destroying its quantum state requires strict nonreciprocity: probe signals must reach the qubit, while reflected or amplifier-generated noise must be blocked from travelling back. Today this is achieved with ferrite-based circulators, bulky, magnetic, fixed-response components that cannot be integrated and dominate the physical footprint and cost of the readout wiring as qubit counts scale toward hundreds or thousands.
This project addresses that bottleneck by developing a fundamentally new class of on-chip hardware: a nonreciprocal circulator based on space-time-modulated superconducting Josephson junctions, using their nonlinearity to break time-reversal symmetry without any magnetic material. Because the modulation is electronically controlled, the circulator's isolation, bandwidth, and routing can be reconfigured and programmed in real time, a key advantage over static ferrite devices, and a natural fit for next-generation quantum control systems that adapt readout and calibration on the fly.
You will develop theoretical and circuit models of space-time-modulated Josephson circuits for on-chip, programmable circulation; design and simulate candidate circulator architectures optimised for compatibility with standard qubit readout chains; and fabricate prototype devices, characterising isolation, noise performance, reconfigurability, and readout fidelity through cryogenic microwave measurements benchmarked against conventional ferrite circulators.
This research targets a bottleneck recognised across the quantum computing community as a key barrier to scaling qubit readout, offering a compact, magnet-free, and programmable route to denser, AI-compatible quantum processors. You'll gain expertise in superconducting circuit design, nonreciprocal electromagnetics, nanofabrication, and cryogenic microwave engineering, within a vibrant research team with strong industrial and academic collaborations.
