Error semitransparent universal control of a bosonic logical qubit

TL;DR

This paper introduces a new framework for universal, error semi-transparent gates on bosonic logical qubits, significantly improving fault-tolerance and operational lifetimes in quantum computing.

Contribution

It presents a novel method using dynamic encoding subspaces to achieve universal error semi-transparent gates with reduced infidelity and extended lifetimes.

Findings

Five-fold reduction in infidelity conditioned on photon loss

Extended active-manipulation lifetimes with quantum error correction

Constructed a non-Clifford operation from a sequence of eight gates

Abstract

Bosonic codes offer hardware-efficient approaches to logical qubit construction and hosted the first demonstration of beyond-break even logical quantum memory. However, such accomplishments were done for idling information, and realization of fault-tolerant logical operations remains a critical bottleneck for universal quantum computation in scaled systems. Error-transparent (ET) gates offer an avenue to resolve this issue, but experimental demonstrations have been limited to phase gates. Here, we introduce a framework based on dynamic encoding subspaces that enables simple linear drives to accomplish universal gates that are error semi-transparent (EsT) to oscillator photon loss. With an EsT logical gate set of {X, H, T}, we observe a five-fold reduction in infidelity conditioned on photon loss, demonstrate extended active-manipulation lifetimes with quantum error correction, and construct a composite EsT non-Clifford operation using a sequence of eight gates from the set. Our approach is compatible with methods for detectable ancilla errors, offering an approach to error-mitigated universal control of bosonic logical qubits with the standard quantum control toolkit.