Error-divisible two-qubit gates

TL;DR

This paper presents a formalism for designing error-divisible two-qubit gates that reduce error proportionally for fractional rotations, potentially improving NISQ algorithm performance.

Contribution

It introduces a set of criteria and protocols for constructing continuous two-qubit gate sets with reduced error, applicable to superconducting qubits with tunable couplers.

Findings

Error-divisible gates reduce fractional rotation errors.

Protocols demonstrated with superconducting qubits.

Potential for significant NISQ performance improvement.

Abstract

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 criteria, and example waveforms and protocols to satisfy them, using superconducting qubits with tunable couplers for constructing continuous gate sets with significantly reduced error for small-angle rotations. If implemented at scale, NISQ algorithm performance would be significantly improved by our error-divisible gate protocols.