Superballistic electron flow through a point contact in a Ga[Al]As heterostructure

We measure electronic transport through point contacts in the high-mobility electron gas a Ga[Al]As heterostructure at different temperatures and bulk densities. The conductance all increases with increasing temperature window around $T \sim 10 K$ for investigated densities contact widths. For high this exceeds fundamental ballistic limit (Sharvin limit). These observations are agreement viscous model previous experiments graphene.