Remote Cross-resonance Gate between Superconducting Fixed-frequency Qubits

• URL: http://arxiv.org/abs/2404.10983v1
• Date: Wed, 17 Apr 2024 01:29:20 GMT
• Title: Remote Cross-resonance Gate between Superconducting Fixed-frequency Qubits
• Authors: Mari Ohfuchi, Shintaro Sato,
• Abstract summary: We propose an alternative remote cross-resonance gate between superconducting fixed-frequency qubits. For 0.25- and 0.5-m cables, remote cross-resonance gates with a concurrence of $>99.9%$ in entanglement generation are obtained. The optimized echoed raised-cosine pulse duration is 150--400 ns, which is similar to the operation time of cross-resonance gates between neighboring qubits on a chip.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: High-fidelity quantum state transfer and remote entanglement between superconducting fixed-frequency qubits have not yet been realized. In this study, we propose an alternative remote cross-resonance gate. Considering multiple modes of a superconducting coaxial cable connecting qubits, we must find conditions under which the cross-resonance gate operates with a certain accuracy even in the presence of qubit frequency shifts due to manufacturing errors. For 0.25- and 0.5-m cables, remote cross-resonance gates with a concurrence of $>99.9\%$ in entanglement generation are obtained even with $\pm$10-MHz frequency shifts. For a 1-m cable with a narrow mode spacing, a concurrence of 99.5\% is achieved by reducing the coupling between the qubits and cable. The optimized echoed raised-cosine pulse duration is 150--400 ns, which is similar to the operation time of cross-resonance gates between neighboring qubits on a chip. The dissipation through the cable modes does not considerably affect the obtained results. Such high-precision quantum interconnects pave the way not only for scaling up quantum computer systems but also for nonlocal connections on a chip.

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