Yi Zhou, Parikshit Ram, et al.
ICLR 2023
Gate-based quantum computers typically encode and process information in two-dimensional units called qubits. Using d-dimensional qudits instead may offer intrinsic advantages, including more efficient circuit synthesis, problem-tailored encodings and embedded error correction. In this work, we design a superconducting qudit-based quantum processor wherein the logical space of transmon qubits is extended to higher-excited levels. We propose a universal gate set featuring a two-qudit cross-resonance entangling gate, for which we predict fidelities beyond 99% in the d=4 case of ququarts with realistic experimental parameters. Furthermore, we present a decomposition routine that compiles general qudit unitaries into these elementary gates, requiring fewer entangling gates than qubit alternatives. As proof-of-concept applications, we numerically demonstrate the synthesis of SU(16) gates for noisy quantum hardware and an embedded error-correction sequence that encodes a qubit memory in a transmon ququart to protect against pure dephasing noise. We conclude that universal qudit control - a valuable extension to the operational toolbox of superconducting quantum information processing - is within reach of current transmon-based architectures and has applications to near-term and long-term hardware.
Yi Zhou, Parikshit Ram, et al.
ICLR 2023
Jonathan Ashley, Brian Marcus, et al.
Ergodic Theory and Dynamical Systems
M. Tismenetsky
International Journal of Computer Mathematics
Andrew Skumanich
SPIE Optics Quebec 1993