Control signal synchronization in superconducting quantum processors

Quantum computers require precise timing of signals to achieve high-fidelity operations. It is typically assumed that a quantum computer’s control system can trigger the generation of signals precisely, but the pulse timing as experienced by the qubits may deviate due to real-world variations like differences in path lengths. For superconducting devices, the delays between pairs of channels can be precisely measured by employing the qubit as a sensor; however, due to finite experimental precision, in aggregate these measurements may be inconsistent and overconstrained.

We present a method for consolidating a collection of pairwise delay measurements into a single set of global timing offsets. When used to adjust pulse triggering, the signals on multiple control channels can be effectively synchronized, as seen by the qubit.

We describe the technique and present an example of its operation using data from Rigetti’s Ankaa™ superconducting quantum computing platform. While the discussion will focus on superconducting qubits, the algorithm itself is applicable to any system where control signals have variable propagation time.