Demonstration of weight-four parity measurements in the surface code architecture

TL;DR

This paper demonstrates high-fidelity weight-four parity measurements in a five-qubit superconducting lattice suitable for surface code quantum error correction, advancing the implementation of scalable quantum computing.

Contribution

It introduces all-microwave controlled parity measurements on a five-qubit lattice with improved gate fidelity by dynamically mitigating Z errors, relevant for surface code architectures.

Findings

Successful encoding of four-qubit parities in X and Z bases.

Full characterization of static and dynamical Z interactions.

Enhanced parity measurement fidelity through modified microwave gates.

Abstract

We present parity measurements on a five-qubit lattice with connectivity amenable to the surface code quantum error correction architecture. Using all-microwave controls of superconducting qubits coupled via resonators, we encode the parities of four data qubit states in either the $X$- or the $Z$-basis. Given the connectivity of the lattice, we perform full characterization of the static $Z$-interactions within the set of five qubits, as well as dynamical $Z$-interactions brought along by single- and two-qubit microwave drives. The parity measurements are significantly improved by modifying the microwave two-qubit gates to dynamically remove non-ideal $Z$ errors.