Non-Destructive Atom Loss Detection and Other Methods for Low-Overhead Control of Hyperfine Qubits

Qubits encoded in internal energy levels of trapped ions and trapped atoms are attractive candidates for error-corrected quantum computation, which is expected to solve certain classes of classically-intractable problems. These hyperfine qubits have been used to demonstrate record-setting performance for all key ingredients of quantum computation [Myerson et al. 2008, Balance et al. 2016, Moses et al. 2023] and early error-correction experiments [Wang et al. 2024, Bluvstein et al. 2024].

Yet, as more qubits are added, the technical complexity grows and fidelity is limited. This critical challenge in maintaining performance while scaling to more qubits reveals the need to develop techniques for easing technical complexity while maintaining high-fidelity control. Over the course of my graduate research, I developed several of these such techniques for low-overhead, high-fidelity control of hyperfine qubits [PRA 108.032407, APL 124.044002, PRApplied 22.014007, arXiv 2405.10434]. These techniques allowed for an order of magnitude reduced infidelity in low-loss state detection of atoms in optical tweezers, an order of magnitude suppression of crosstalk in parallel single-qubit gates, an order of magnitude improved robustness to frequency error in entangling gates, and a first-of-its-kind demonstration of non-destructive detection of atom-loss errors, respectively. While all these results represent significant progress towards scalable quantum computation with hyperfine qubits, herein I focus on the latest result.

Atom loss is an inevitable problem for neutral atom platforms at scale, and typical detection methods cannot be employed as they would disturb the encoded quantum information. In our proof-of-principle experiment we perform the first ever detection of atom loss errors while maintaining coherence in remaining atoms. This represents a critical step towards a regime where the quantum information may persist beyond the physical lifetime of any individual atom.