Group seminar at LMU and Zoom: Mitigation of atom-loss errors for neutral atom quantum computing

Matthew Chow, Sandia National Laboratories, New Mexico, USA
Group seminar at LMU seminar room and Zoom
Tuesday, 24 September, 09:00am (MEZ)

Neutral atoms have emerged as a promising platform for quantum computation. However, as the traps that hold the individual atoms are weak, loss of atoms from the trap (e.g. due to background gas collisions) is essentially inevitable for any sufficiently long computation, presenting a critical challenge. Traditional methods of directly detecting which atoms are missing cannot be employed on data-carrying atoms during computation as they disturb the quantum information.

In this seminar, I will discuss our work mitigating the impact of atom loss for neutral atom quantum processors. First, I will discuss our previous results with (projective) high-fidelity, low-loss state detection of cesium atoms trapped in optical tweezers. Then I will discuss how we used this three-outcome measurement technique to benchmark the performance of quantum circuits known as Leakage Detection Units (LDUs) for non-destructively detecting atom-loss errors (and more generally a class of errors known as leakage errors). An LDU maps the information about the presence or absence of a data atom onto the state of an extra ancilla atom without changing the internal state of the data atom. We experimentally demonstrate that an LDU identifies data atom loss with 93.4% accuracy while preserving coherence, limited primarily by our two-qubit gate fidelity. I will further describe a variation of the LDU wherein the roles of the original data and ancilla atoms are exchanged after the LDU, which could allow for simultaneous detection of atom-loss errors and effective cooling of the quantum register by replacing old hot atoms with fresh reservoir atoms.