for a distance of 500 $\mu$m is around 50%.

The dynamics of the IX transport was probed by time-resolved PL measurements at the end of the SAW transport channel, as illustrated in Fig. \[Fig1\](d). From the delay of the PL pulse onset we calculate a maximum propagation velocity of 2.4$\pm$0.1 $\mu$m/ns, which is close to the SAW group velocity of ${v_\mathrm{SAW}}$=2.6$\pm$0.1 $\mu$m/ns. The width of the PL pulse is determined by the initial size of the IX cloud created by the pulsed laser excitation. We observe a slight broadening of the PL profile as well as the development of a tail with increasing transport distances. These features, which will be addressed in details elsewhere,[@Ref25] are attributed to trapping sites along the transport path induced by potential fluctuations, which capture IX and delay their propagation. The transport within well-defined $\mu$m-sized packets over long distances and at constant velocity contrasts with conventional diffusion [@Ref18] or drift-driven [@Ref15; @Ref16; @Ref17; @Ref19; @Ref20] processes, where the IX fluid undergoes self-expansion. In addition, it enables synchronization with pulsed optical excitation by appropriately selecting the SAW frequency.

Acoustic exciton transistor - EXAT {#SecEXAT}
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The SAW-driven long-range IX flow can be efficiently controlled by the EXAT 