Error-detectable Universal Control for High-Gain Bosonic Quantum Error Correction

TL;DR

This paper introduces an error-detectable universal control method for bosonic quantum error correction, significantly improving logical qubit coherence times by detecting and discarding error-inducing events, paving the way for fault-tolerant quantum computing.

Contribution

It presents a novel control technique that detects ancilla relaxation events to suppress operational errors in bosonic QEC, achieving high fidelity gates and substantial QEC gains.

Findings

Achieved >99.6% gate fidelity with bosonic codes.

Demonstrated QEC gains of 8.33× beyond break-even.

Showed potential for >10× QEC gains with current technology.

Abstract

Protecting quantum information through quantum error correction (QEC) is a cornerstone of future fault-tolerant quantum computation. However, current QEC-protected logical qubits have only achieved coherence times about twice those of their best physical constituents. Here, we show that the primary barrier to higher QEC gains is ancilla-induced operational errors rather than intrinsic cavity coherence. To overcome this bottleneck, we introduce error-detectable universal control of bosonic modes, wherein ancilla relaxation events are detected and the corresponding trajectories discarded, thereby suppressing operational errors on logical qubits. For binomial codes, we demonstrate universal gates with fidelities exceeding $99.6\%$ and QEC gains of $8.33\times$ beyond break-even. Our results establish that gains beyond $10\times$ are achievable with state-of-the-art devices, establishing a path toward fault-tolerant bosonic quantum computing.