  One of the key challenges in current Noisy Intermediate-Scale Quantum (NISQ)
computers is to control a quantum system with high-fidelity quantum gates.
There are many reasons a quantum gate can go wrong -- for superconducting
transmon qubits in particular, one major source of gate error is the unwanted
crosstalk between neighboring qubits due to a phenomenon called frequency
crowding. We motivate a systematic approach for understanding and mitigating
the crosstalk noise when executing near-term quantum programs on
superconducting NISQ computers. We present a general software solution to
alleviate frequency crowding by systematically tuning qubit frequencies
according to input programs, trading parallelism for higher gate fidelity when
necessary. The net result is that our work dramatically improves the crosstalk
resilience of tunable-qubit, fixed-coupler hardware, matching or surpassing
other more complex architectural designs such as tunable-coupler systems. On
NISQ benchmarks, we improve worst-case program success rate by 13.3x on
average, compared to existing traditional serialization strategies.
