July 4, 2025
Journal Article

Symmetry-mediated quantum coherence of W5+ spins in an oxygen-deficient double perovskite

Abstract

Elucidating the factors limiting quantum coherence in real materials is essential to the development of quantum technologies. Here we report a strategic approach to determine the effect of lattice dynamics on spin coherence lifetimes using oxygen deficient double perovskites as host materials. In addition to obtaining millisecond T1 spin-lattice lifetimes at T ~ 10 K, measurable quantum superpositions were observed up to room temperature. We determine that T2 enhancement in Sr2CaWO6 d over previously studied Ba2CaWO6 d is caused by a dynamically-driven increase in effective site symmetry around the dominant paramagnetic site, assigned as W5+ via electron paramagnetic resonance spectroscopy. Further, a combination of experimental and computational techniques enabled quantification of the relative strength of spin-phonon coupling of each phonon mode. This analysis demonstrates the effect of thermodynamics and site symmetry on the spin lifetimes of W5+ paramagnetic defects, an important step in the process of reducing decoherence to produce longer-lived qubits.

Published: July 4, 2025

Citation

Bernier S., M. Sinha, T.J. Pearson, P.V. Sushko, P.H. Oyala, M.A. Siegler, and W.A. Phelan, et al. 2025. Symmetry-mediated quantum coherence of W5+ spins in an oxygen-deficient double perovskite. npj Quantum Materials 10:Art. No. 62. PNNL-SA-208748. doi:10.1038/s41535-025-00782-3

Research topics