Optical control of atomic qubits looks like the only way to scaling quantum computers. However, mid-circuit quantum measurement/reset can be challenging in atomic systems, owing to the use of resonance fluorescence. Even a single resonant photon can destroy quantum coherence in data qubits. Conventional approaches to isolate data qubits from those to be measured involve using multiple species (spectral isolation) or atomic shuttling (spatial isolation). Here we perform mid-circuit quantum measurement/reset with a single species atomic qubit system and without any shuttling — all done in software. Our demonstrations, in two different atomic systems, follow previous omg* ideas on using auxiliary energy levels in a single atom for different types of qubits that are spectrally resolved. Notably, we demonstrate the components of the schemes by leaving the data qubits alone and performing all shelving and measurement operations on jut the qubits to be measured/reset.
- 171Yb+: “In-situ mid-circuit qubit measurement and reset in a single-species trapped-ion quantum computing system,” Y. Yu, K. Yan, D. Biswas, N. Zhang, B. Harraz, C. Noel, C. Monroe, and A. Kozhanov, arXiv:2504.12544 (2025).
- 138Ba+: “Non-invasive mid-circuit measurement and reset on atomic qubits,” Z.-Y. Chen, I. Goetting, G. Toh, Y. Yu, M. Shalaev, S. Saha, A. Kalakuntla, H. Shi, C. Monroe, A. Kozhanov, and C. Noel, arXiv 2504.12538 (2025).
* omg is a goofy acronym that stands for “optical/metastable/ground” state qubits
