Electromagnetic field and surface acoustic wave induced decoherence in a ballistic quantum interferometer

We report the studies of decoherence processes of a ballistic electronic quantum interferometer in the presence of high frequency electromagnetic (EM) field and surface acoustic wave (SAW). The device is comprised of an Aharonov-Bohm (AB) ring sandwiched in between two interdigital transducers (IDTs), where AB ring serves as a phase sensor and the IDTs function as a controlled environmental noise source. We apply surface acoustic wave (SAW) launched by the IDT through the ring, and extract the decoherence rate from AB oscillations. We investigate the interplay of the dephasing process induced by the fluctuations of the thermal electromagnetic (EM) field, SAW and the acousto-electric current. We obtain a spectrum map of decoherence with the applied rf-power, and based on which we observe high-frequency EM filed induced phase-breaking without thermal heating and identify the conditions of SAW operation without dephasing. The mechanism of decoherence is attributed to the enhancement of the charge-charge interactions in the presence of EM-field and SAW. Our study has strong implications on developing the flying-qubit techniques by utilizing surface acoustic effects.