Scalable simultaneous multi-qubit readout with 99.99% single-shot fidelity

TL;DR

This paper demonstrates a highly scalable, high-fidelity single-shot readout method for multi-qubit trapped-ion systems using space and time-resolved camera detection, achieving near-perfect fidelity and minimal cross-talk.

Contribution

The authors introduce a scalable readout technique for multi-qubit trapped-ion registers with 99.99% fidelity, suitable for large qubit arrays with minimal cross-talk.

Findings

Single-qubit readout error of 0.00009 in 400us exposure

Four-qubit register error of 0.0001 per qubit

Method scalable to ~10,000 qubits with negligible fidelity loss

Abstract

We describe single-shot readout of a trapped-ion multi-qubit register using space and time-resolved camera detection. For a single qubit we measure 0.9(3)x10^{-4} readout error in 400us exposure time, limited by the qubit's decay lifetime. For a four-qubit register (a "qunybble") we measure an additional error of only 0.1(1)x10^{-4} per qubit, despite the presence of 4% optical cross-talk between neighbouring qubits. A study of the cross-talk indicates that the method would scale with negligible loss of fidelity to ~10000 qubits at a density <~1 qubit/um^2, with a readout time ~1us/qubit.