Metastable atomic qubits are a highly promising platform for the realization of quantum computers, owing to their scalability and the possibility of converting leakage errors to erasure errors mid-circuit. The new work, which originated at the MPQ and has now been published in Physical Review Letters, highlights the new metastable fine-structure qubit, based on the long-lived clock states of strontium-88, as a promising building block for scalable quantum computers because it combines high-quality universal gates with a natural atomic, long-lived implementation. The central architectural idea is particularly attractive for fault-tolerant computing. By deliberately excluding the ground state from the qubit subspace, leakage errors can be specifically converted into erasure errors and thus detected much more effectively during the computation. This is complemented by spin-selective mapping within the qubit manifold, which allows for state-resolved readout and post-selection of successful computation results, thus representing an important step toward robust, error-corrected quantum processors based on neutral atoms.
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