Faster and More Reliable Quantum SWAPs via Native Gates
Due to the sparse connectivity of superconducting quantum computers, qubit
communication via SWAP gates accounts for the vast majority of overhead in
quantum programs. We introduce a method for improving the speed and reliability
of SWAPs at the level of the superconducting hardware's native gateset. Our
method relies on four techniques: 1) SWAP Orientation, 2) Cross-Gate Pulse
Cancellation, 3) Commutation through Cross-Resonance, and 4) Cross-Resonance
Polarity. Importantly, our Optimized SWAP is bootstrapped from the
pre-calibrated gates, and therefore incurs zero calibration overhead. We
experimentally evaluate our optimizations with Qiskit Pulse on IBM hardware.
Our Optimized SWAP is 11% faster and 13% more reliable than the Standard SWAP.
We also experimentally validate our optimizations on application-level
benchmarks. Due to (a) the multiplicatively compounding gains from improved
SWAPs and (b) the frequency of SWAPs, we observe typical improvements in
success probability of 10-40%. The Optimized SWAP is available through the
SuperstaQ platform.
Pranav Gokhale Teague Tomesh Martin Suchara Frederic T. Chong