Error-Divisible Two-Qubit Gates

We introduce a simple widely applicable formalism for designing error-divisible two-qubit gates: a quantum gate set where fractional rotations have proportionally reduced error compared to the full entangling gate. In current noisy intermediate-scale quantum (NISQ) algorithms, performance is largely constrained by error proliferation at high circuit depths, of which two-qubit gate error is generally the dominant contribution. Further, in many hardware implementations, arbitrary two-qubit rotations must be composed from multiple two-qubit stock gates, further increasing error. This work introduces a set of cri-teria, and example wave forms and protocols to satisfy them, using superconducting qubits with tunable couplers for constructing continuous gate sets with significantly reduced leakage and dynamic ZZ errors for small-angle rotations. If implemented at scale, NISQ-algorithm performance could be significantly improved by our error-divisible gate protocols.

Automated summary

We propose a simple and widely applicable framework for designing error-divisible two-qubit gates, which can reduce errors in fractional rotations compared to full entangling gates. In noisy intermediate-scale quantum (NISQ) algorithms, error propagation at high circuit depths, especially in two-qubit gates, limits performance. This work introduces criteria, waveforms, and protocols for constructing continuous gate sets with reduced leakage and dynamic ZZ errors using superconducting qubits and tunable couplers. Implementing our error-divisible gate protocols at scale could significantly improve NISQ algorithm performance.