Erasure detection of a dual-rail qubit encoded in a double-post superconducting cavity

• URL: http://arxiv.org/abs/2311.04423v2
• Date: Fri, 17 Nov 2023 15:25:15 GMT
• Title: Erasure detection of a dual-rail qubit encoded in a double-post superconducting cavity
• Authors: Akshay Koottandavida, Ioannis Tsioutsios, Aikaterini Kargioti, Cassady R. Smith, Vidul R. Joshi, Wei Dai, James D. Teoh, Jacob C. Curtis, Luigi Frunzio, Robert J. Schoelkopf, Michel H. Devoret
• Abstract summary: We implement a dual-rail qubit encoded in a compact, double-post superconducting cavity. We measure an erasure rate of 3.981 +/- 0.003 (ms)-1 and a residual dephasing error rate up to 0.17 (ms)-1 within the codespace.
• Score: 1.8484713576684788
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Qubits with predominantly erasure errors present distinctive advantages for quantum error correction(QEC) and fault tolerant quantum computing. Logical qubits based on dual-rail encoding that exploit erasure detection have been recently proposed in superconducting circuit architectures, either with coupled transmons or cavities. Here, we implement a dual-rail qubit encoded in a compact, double-post superconducting cavity. Using an auxiliary transmon, we perform erasure detection on the dual-rail subspace. We characterize the behaviour of the codespace by a novel method to perform joint-Wigner tomography. This is based on modifying the cross-Kerr interaction between the cavity modes and the transmon. We measure an erasure rate of 3.981 +/- 0.003 (ms)-1 and a residual dephasing error rate up to 0.17 (ms)-1 within the codespace. This strong hierarchy of error rates, together with the compact and hardware-efficient nature of this novel architecture, hold promise in realising QEC schemes with enhanced thresholds and improved scaling.

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