  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.
