Hardware-Efficient Microwave-Activated Tunable Coupling Between Superconducting Qubits

• URL: http://arxiv.org/abs/2105.05384v1
• Date: Wed, 12 May 2021 01:06:08 GMT
• Title: Hardware-Efficient Microwave-Activated Tunable Coupling Between Superconducting Qubits
• Authors: Bradley K. Mitchell, Ravi K. Naik, Alexis Morvan, Akel Hashim, John Mark Kreikebaum, Brian Marinelli, Wim Lavrijsen, Kasra Nowrouzi, David I. Santiago, and Irfan Siddiqi
• Abstract summary: We realize a tunable $ZZ$ interaction between two transmon qubits with fixed frequencies and fixed coupling. Because both transmons are driven, it is resilient to microwave crosstalk. We apply this interaction to implement a controlled phase (CZ) gate with a gate fidelity of $99.43(1)%$ as measured by cycle benchmarking.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Generating high-fidelity, tunable entanglement between qubits is crucial for realizing gate-based quantum computation. In superconducting circuits, tunable interactions are often implemented using flux-tunable qubits or coupling elements, adding control complexity and noise sources. Here, we realize a tunable $ZZ$ interaction between two transmon qubits with fixed frequencies and fixed coupling, induced by driving both transmons off-resonantly. We show tunable coupling over one order of magnitude larger than the static coupling, and change the sign of the interaction, enabling cancellation of the idle coupling. Further, this interaction is amenable to large quantum processors: the drive frequency can be flexibly chosen to avoid spurious transitions, and because both transmons are driven, it is resilient to microwave crosstalk. We apply this interaction to implement a controlled phase (CZ) gate with a gate fidelity of $99.43(1)\%$ as measured by cycle benchmarking, and we find the fidelity is limited by incoherent errors.

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