Reducing the Sensitivity of Quantum Gates to Laser Intensity Noise via Real-Time Feedback on Gate Parameters

Quantum processors using laser fields to drive qubits suffer from laser intensity fluctuations which limit gate fidelities [1-4]. Mitigation of such noise processes via feedback was up until now only available via low bandwidth sequencers running on CPUs (allowing at best for shot to shot corrections) or on FPGA processors and analog circuits that take orders of magnitude longer to develop and iterate on.

In this talk, we demonstrate a novel hardware and software architecture allowing the generation of high bandwidth (>250kHz) feedback programs written in a Turing-complete, high-level programming language called QUA. The approach is based on the real-time synthesis of signals using QM’s pulse processor, a novel chip architecture and instruction set designed to generate quantum circuits.

The pulse processor allows adapting gate waveforms in real-time based on acquired error signals such as laser intensity fluctuations measured on fast photodiodes. The user can write arbitrary control programs in QUA, which are then compiled and run in real-time on the pulse processor establishing feedback bandwidths exceeding 250kHz, often limited by latencies introduced by propagation delays in the lab.