Optimal control of a superconducting qutrit via a low-noise broadband optical link*

Photonic links enable the direct generation of microwave control signals for superconducting devices at cryogenic temperatures, reducing the heat load impacts of the coaxial lines and removing the thermal background carried by those cables. These links also enable adoption of microwave photonic techniques that have improved signal to noise and distortion ratios compared with conventional electronic digital to analog converters. Quantum optimal control methods enable arbitrary, high-fidelity control of multilevel quantum systems through the direct implementation of complex unitaries and pre-compiled gate sequences. In this talk, I will describe how we integrated a photonic digital to analog converter (PDAC) with a microwave control system targeting a superconducting qutrit. We demonstrated basic control by using photonically-generated control pulses to measure energy- and phase- coherence, and then generated and tested an optimal-control implementation of the 0-2 SWAP gate with the PDAC, demonstrating arbitrary control signal generation for superconducting devices via photonic links.