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

• URL: http://arxiv.org/abs/2206.12392v2
• Date: Thu, 30 Mar 2023 08:06:27 GMT
• Title: Controlled-Controlled-Phase Gates for Superconducting Qubits Mediated by a Shared Tunable Coupler
• Authors: Niklas J. Glaser, Federico Roy, Stefan Filipp
• Abstract summary: 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. Numerical simulations result in fidelities around 99 % and gate times below 300 ns.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• 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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