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arXiv · 2304.11159

Exploring Ququart Computation on a Transmon using Optimal Control

Lennart Maximilian Seifert·Ziqian Li·Tanay Roy·David I. Schuster·Frederic T. Chong·Jonathan M. Baker
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Abstract

Contemporary quantum computers encode and process quantum information in binary qubits (d = 2). However, many architectures include higher energy levels that are left as unused computational resources. We demonstrate a superconducting ququart (d = 4) processor and combine quantum optimal control with efficient gate decompositions to implement high-fidelity ququart gates. We distinguish between viewing the ququart as a generalized four-level qubit and an encoded pair of qubits, and characterize the resulting gates in each case. In randomized benchmarking experiments we observe gate fidelities greater 95% and identify coherence as the primary limiting factor. Our results validate ququarts as a viable tool for quantum information processing.

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Lennart Maximilian Seifert, Ziqian Li, Tanay Roy, David I. Schuster, Frederic T. Chong, Jonathan M. Baker. 2023-04-21. Exploring Ququart Computation on a Transmon using Optimal Control. https://doi.org/10.1103/physreva.108.062609

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