We develop electro-optical systems for photonic generation and delivery of micro- and millimeter-wave signals to superconducting circuit platforms.
Microwave photonics, where optical systems are employed to transport, filter, generate, or otherwise process microwave and millimeter wave signals, takes advantage of the large bandwidth, low loss, and low noise of optical systems, as well as the long reach of optical fiber interconnects. We are exploiting photonic links to connect room temperature microwave sources to superconducting circuits, motivated by the unique challenges inherent in transporting microwave and millimeter-wave signals into a cryogenic environment using cables and waveguides. For example, wiring up a large number of coaxial cables can present a significant heat load in quantum information processing systems that rely on superconducting qubits, whereas the thermal conductivity of optical fiber is ~1000x less. As another example Josephson junction-based voltage standards are transiting to the generation of high-speed waveforms that require drive signal bandwidths exceeding 100 GHz. Optical sources can readily generate > 1 THz of bandwidth, and optical fibers can transport rf, microwave, and mm-wave signals with negligible signal distortion and loss. When combined with high-speed photodiodes compatible with cryogenic operation, cryogenic photonic links become an attractive solution for delivering signals to superconducting platforms.
We develop optical sources and fiber optic interconnects to deliver user-defined pulse patterns to superconducting circuits. Uses include delivering control and readout signals for quantum information systems as well as for Josephson junction-based waveform synthesis.