Demonstrating a Long-Coherence Dual-Rail Erasure Qubit Using Tunable Transmons
Harry Levine, Arbel Haim, Jimmy S. C. Hung, Nasser Alidoust, Mahmoud Kalaee, Laura DeLorenzo, E. Alex Wollack, Patricio Arrangoiz-Arriola, Amirhossein Khalajhedayati, Rohan Sanil, Hesam Moradinejad, Yotam Vaknin, Aleksander Kubica, David J. Hover, Shahriar Aghaeimeibodi, Joshua Ari Alcid, Chungheon Baek, J. Barnett, K. Bawdekar, Przemysław Bienias · Physical Review X · 2024
Quantum error correction with erasure qubits promises significant advantages over standard error correction due to favorable thresholds for erasure errors. To realize this advantage in practice requires a qubit for which nearly all errors are such erasure errors, and the ability to check for erasure errors without dephasing the qubit. We demonstrate that a “dual-rail qubit” consisting of a pair of resonantly coupled transmons can form a highly coherent erasure qubit, where transmon T 1 errors are converted into erasure errors and residual dephasing is strongly suppressed, leading to millisecond-scale coherence within the qubit subspace. We show that single-qubit gates are limited primarily by erasure errors, with erasure probability p erasure = 2.19 ( 2 ) × 10 − 3 per gate while the residual errors are ∼ 40 times lower. We further demonstrate midcircuit detection of erasure errors while introducing < 0.1 % dephasing error per check. Finally, we show that the suppression of transmon noise allows this dual-rail qubit to preserve high coherence over a broad tunable operating range, offering an improved capacity to avoid frequency collisions. This work establishes transmon-based dual-rail qubits as an attractive building block for hardware-efficient quantum error correction. Published by the American Physical Society 2024