Fluid transport in extreme regimes: from nanofluidics to quantum interfaces

by Dr Baptiste Coquinot (Institute of Science & Technology of Austria)

Monday 11 May 2026, 15:00 → 16:30 Europe/Rome

1/3-1 - Sala R (Dipartimento di Fisica e Astronomia - Edificio Marzolo)

At the nanoscale, interfacial cross-effects couple charge, mass, and heat transport in confined electrolytes. In the first part, we extend this framework by including the electronic degrees of freedom of the confining solid, thereby coupling nanofluidic and electronic transport. These interactions arise either directly, via electrostatic coupling that generates an interfacial capacitance between ions and conduction electrons, or indirectly through fluctuation-induced mechanisms associated with spectral overlap of charge fluctuations in the electrolyte and the solid. This unified picture yields reciprocal electrohydrodynamic effects: fluid flow can drive electronic currents, while applied currents can induce fluid motion. These couplings also allow nanoscale hydroelectric conversion, where viscous flows generate electrical currents. In addition, the frequency-dependent response of ionic modes enables ion-specific friction, opening routes to spectral selectivity. Under AC driving, interfacial capacitance mediates charge exchange between ionic and electronic channels; in conducting nanochannels, this effectively bypasses ionic resistance and enhances transport.

In the second part, we extend this framework to quantum fluids by reaching the superfluid regime, using either helium or ultracold Bose–Einstein condensates. The same fluctuation-induced couplings then govern a fully quantum solid–liquid interface. In this regime, they affect not only dissipation but also the ground state. We show that tuning the solid’s degrees of freedom provides a handle to control the interfacial quantum state and can drive a transition toward supersolidity—an exotic phase combining crystalline order with superfluid transport.