Phonon blockade in an acoustic cavity coupled to a three-level artificial atom

We theoretically investigated the phonon statistics of an acoustic cavity coupled to a three-level ladder-type artificial atom. Based on the wave function method, we elucidated the optimal conditions for a strong phonon antibunching effect at zero temperature and observed the coexistence of both conventional and unconventional phonon blockades. Particularly, intersection points occurred between the antibunching structures of both blockades at a certain controlled field strength. Importantly, compared to the conventional/unconventional phonon blockade, simultaneously strong antibunching and high brightness (mean phonon number) were realized at the intersection point. Further, phonon blockade at a finite temperature was studied. We showed that thermal noise affected the phonon blockade only at temperatures exceeding a certain threshold value. More interestingly, the conventional phonon blockade was more robust against thermal noise than the unconventional phonon blockade. Thus, this work provides a scheme for preparing high-quality single-phonon sources at finite temperatures.