Randomized benchmarking of a high-fidelity remote CNOT gate over a meter-scale microwave interconnect

Understand

High-fidelity, meter-scale microwave interconnects between superconducting quantum processor modules are a key technology for extending system size beyond constraints imposed by device manufacturing equipment, yield, and signal delivery.

• Although tomographic experiments have been used in previous demonstrations for benchmarking remote state transfer between modules, they do not reliably separate State Preparation and Measurement (SPAM) error from the error per state transfer.
• Recent developments based on randomized benchmarking provide a compatible theory for separating these two errors.
• In this work, we present a module-to-module interconnect based on Tunable-Coupling Qubits (TCQs) and benchmark, in a SPAM-error-tolerant manner enabled by a frame-tracking technique, a remote state transfer fidelity of 0.988 across a 60cm-long coplanar waveguide (CPW).