Decoherence in a ballistic quantum interferometer due to the interplay of radio-frequency electromagnetic field and surface acoustic wave

We report on studies of the decoherence processes of a ballistic quantum interferometer subjected to a radio-frequency (RF) electromagnetic (EM) field and a surface acoustic wave (SAW). The device consists of an Aharonov-Bohm (AB) ring sandwiched between two interdigital transducers (IDTs), where the AB ring serves as a phase sensor and the IDTs function as a controlled source of environmental noise. By employing the IDTs with an RF-EM field to launch a SAW train through the ring, we extract the decoherence rate Γ_φ from the AB oscillation amplitude and investigate the dephasing process through the RF power P_rf dependence of Γ_φ, the electronic temperature T_s, and acoustoelectric current I_ae spectrum. Our data reveal that the bandwidth-narrowing feature caused by Bragg reflections of the SAW is consistently found in the spectra of Γ₀,T_s, and I_ae, suggesting that the piezoelectric field is the dominant EM field contributing to decoherence. At the resonance frequency, the decoherence rate follows P_rf^1/5 dependence due to thermal fluctuation of the alternating electric current by the EM field. At the off-resonance condition, we identify that the asymmetric Γ₀ spectrum is induced by the crosstalk of SAW interference under the influence of a weak P_rf. Furthermore, we find the optimal conditions for operating the SAW to minimize dephasing without thermal heating. The underlying mechanism responsible for the decoherence is attributed to the enhancement of charge-charge interactions in the presence of the EM field and the SAW. These findings are crucial for the development of quantum electronic devices leveraging SAW technology. © 2025 American Physical Society.