Universal Single Qutrit Gate in Ultracold ⁸⁷Rb

Compared to a qubit processor with an equivalent number of interconnected qudits, a qutrit processor has access to a larger computational Hilbert space, and thus can solve more complex problems. A single qutrit can be used to demonstrate quantum speedup, contains double the information of a single qubit, and unlike the qubit it has no classical analog. Favourably, a third eigenstate is available for quantum computation in systems that are conventionally used for qubits, among those are photonic and superconducting circuits, trapped ions, NV centers, and neutral atoms.

A common method to perform arbitrary single qutrit gates is to decompose the SU(3) operation into three SU(2) Givens rotations, one between each pair of eigenstates. A direct single-photon transition between two of these states may be forbidden by selection rules, leaving only two direct couplings. Conventionally, this necessitates two-photon transitions or several additional π rotations to implement a general SU(3) operation. In a proposal for trapped ion quantum computers, Klimov et al. suggested a resonant dual-tone transition for facilitating fast transitions between the indirectly coupled levels. We present the first experimental demonstration of this proposal in our ultracold neutral-atom system.