Collective preparation of large quantum registers with high fidelity

TL;DR

This paper demonstrates the preparation of a large 5612-qubit quantum register with very high fidelity using an improved cooperative protocol, surpassing limitations of standard reset methods.

Contribution

It introduces an enhanced cooperative quantum information erasure protocol applied to a large superconducting qubit network, achieving unprecedented global fidelity.

Findings

Prepared a 5612-qubit register with fidelity ~0.9956

Applied a cooperative protocol to avoid orthogonality catastrophe

Achieved high global fidelity despite high individual reset errors

Abstract

We report on the preparation of a large quantum register of 5612 qubits, with the unprecedented high global fidelity of $F\simeq 0.9956$. This was achieved by applying an improved cooperative quantum information erasure (CQIE) protocol [Buffoni, L. and Campisi, M., Quantum 7, 961 (2023)] to a programmable network of superconducting qubits featuring a high connectivity. At variance with the standard method based on the individual reset of each qubit in parallel, here the quantum register is treated as a whole, thus avoiding the well-known orthogonality catastrophe wehereby even an extremely high individual reset fidelity $f$ results in vanishing global fidelities $F=f^N$ with growing number $N$ of qubits.