A leakage-resilient approach to fault-tolerant quantum computing with superconducting elements

TL;DR

This paper introduces a leakage-resilient method for fault-tolerant quantum computing with superconducting qubits, addressing leakage errors by using swap operations to enhance error correction in surface codes.

Contribution

It proposes a novel leakage-resilient measurement scheme for multiqubit stabilizers and integrates it into surface code quantum error correction for superconducting circuits.

Findings

Reduces leakage errors during stabilizer measurements

Enables persistent leakage error prevention in surface code protocols

Improves fault-tolerance in superconducting quantum computing

Abstract

Superconducting qubits, while promising for scalability and long coherence times, contain more than two energy levels, and therefore are susceptible to errors generated by the leakage of population outside of the computational subspace. Such leakage errors constitute a prominent roadblock towards fault-tolerant quantum computing (FTQC) with superconducting qubits. FTQC using topological codes is based on sequential measurements of multiqubit stabilizer operators. Here, we first propose a leakage-resilient procedure to perform repetitive measurements of multiqubit stabilizer operators, and then use this scheme as an ingredient to develop a leakage-resilient approach for surface code quantum error correction with superconducting circuits. Our protocol is based on swap operations between data and ancilla qubits at the end of every cycle, requiring read-out and reset operations on every physical qubit in the system, and thereby preventing persistent leakage errors from occurring.