Slip electron flow in GaAs microscale constrictions

Hydrodynamic electron transport in solids, governed by momentum-conserving electron-electron collisions, offers a unique framework to explore collective phenomena. Within this framework, correlated electron motion is modeled as viscous fluid flow, with viscosity serving as the interaction parameter. Advances in electron hydrodynamics remain constrained by two unresolved issues: the questionable existence of perfect boundary slip$\unicode{x2013}$a hallmark of frictionless transport$\unicode{x2013}$in electron fluids, and the lack of quantitative experimental confirmation of the theoretical relation linking the viscosity to electron-electron scattering length. Here, we resolve this through independent measurements of these quantities in the same electron system in GaAs/AlGaAs heterostructure. Our experiments provide direct evidence of perfect boundary slip in microscale constrictions$\unicode{x2013}$unprecedented phenomenon for electron liquid that parallels ultrafast water transport in carbon nanotubes. These findings bridge the fields of electron hydrodynamics and nanofluidics, highlighting the transformative potential of hydrodynamic engineering across condensed matter and fluidic technologies.