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arXiv · 2206.12392

Controlled-Controlled-Phase Gates for Superconducting Qubits Mediated by a Shared Tunable Coupler

Niklas J. Glaser·Federico Roy·Stefan Filipp
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Abstract

Applications for noisy intermediate-scale quantum computing devices rely on the efficient entanglement of many qubits to reach a potential quantum advantage. Although entanglement is typically generated using two-qubit gates, direct control of strong multi-qubit interactions can improve the efficiency of the process. Here, we investigate a system of three superconducting transmon-type qubits coupled via a single flux-tunable coupler. Tuning the frequency of the coupler by adiabatic flux pulses enables us to control the conditional energy shifts between the qubits and directly realize multi-qubit interactions. To accurately adjust the resulting controlled relative phases, we describe a gate protocol involving refocusing pulses and adjustable interaction times. This enables the implementation of the full family of pairwise controlled-phase (CPHASE) and controlled-controlled-phase (CCPHASE) gates. Numerical simulations result in fidelities around 99 % and gate times below 300 ns using currently achievable system parameters and decoherence rates.

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Niklas J. Glaser, Federico Roy, Stefan Filipp. 2022-06-24. Controlled-Controlled-Phase Gates for Superconducting Qubits Mediated by a Shared Tunable Coupler. https://doi.org/10.1103/physrevapplied.19.044001

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