We implement in-situ mid-circuit measurement and reset (MCMR) operations on a trapped-ion quantum computing system by using metastable qubit states in 171Yb+ ions. We introduce and compare two methods for isolating data qubits from measured qubits: one shelves the data qubit into the metastable state and the other drives the measured qubit to the metastable state without disturbing the other qubits. We experimentally demonstrate both methods on a crystal of two 171Yb+ ions using both the S1/2 ground state hyperfine clock qubit and the S1/2-D3/2 optical qubit. These MCMR methods result in errors on the data qubit of about 2% without degrading the measurement fidelity. With straightforward reductions in laser noise, these errors can be suppressed to less than 0.1%. The demonstrated method allows MCMR to be performed in a single-species ion chain without shuttling or additional qubit-addressing optics, greatly simplifying the architecture.
@article{arxiv.2504.12544,
title = {In-situ mid-circuit qubit measurement and reset in a single-species trapped-ion quantum computing system},
author = {Yichao Yu and Keqin Yan and Debopriyo Biswas and Vivian Ni Zhang and Bahaa Harraz and Crystal Noel and Christopher Monroe and Alexander Kozhanov},
journal= {arXiv preprint arXiv:2504.12544},
year = {2025}
}