Year: 2024
Type: article
Abstract: Spin-spin exchange interactions between semiconductor spin qubits allow for fast single- and two-qubit gates. During exchange, coupling of the qubits to a surrounding phonon bath may cause errors in the resulting gate. Here, the fidelities of exchange operations with semiconductor double quantum dot spin qubits in a Si-SiGe heterostructure coupled to a finite-temperature phonon bath are considered. By employing a master-equation approach, the isolated effect of each spin-phonon coupling term may be resolved, as well as leakage errors of encoded qubit operations. As the temperature is increased, a crossover is observed from where the primary source of error is due to a phonon-induced perturbation of the two-electron spin states, to one where the phonon-induced coupling to an excited orbital state becomes the dominant error. Additionally, it is shown that a simple tradeoff in pulse shape and length can improve robustness to spin-phonon-induced errors during gate operations by up to an order of magnitude. Our results suggest that for elevated temperatures within $200--300\phantom{\rule{0.16em}{0ex}}\mathrm{mK}$, exchange gate operations are not currently limited by bulk phonons. This is consistent with recent experiments.
Authors: Matthew Brooks, Rex Lundgren, Charles Tahan
Institution: University of Maryland, College Park
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4405424077