20 research outputs found
Interaction confinement and electronic screening in two-dimensional nanofluidic channels
The transport of fluids at the nanoscale is fundamental to manifold
biological and industrial processes, ranging from neurotransmission to
ultrafiltration. Yet, it is only recently that well-controlled channels with
cross-sections as small as a few molecular diameters became an experimental
reality. When aqueous electrolytes are confined within such channels, the
Coulomb interactions between the dissolved ions are reinforced due to
dielectric contrast at the channel walls: we dub this effect `interaction
confinement'. Yet, no systematic way of computing these confined interactions
has been proposed beyond the limiting cases of perfectly metallic or perfectly
insulating channel walls. Here, we introduce a new formalism, based on the
so-called surface response functions, that expresses the effective Coulomb
interactions within a two-dimensional channel in terms of the wall's electronic
structure, described to any desired level of precision. We use it to
demonstrate that in few-nanometer-wide channels, the ionic interactions can be
tuned by the wall material's screening length. We illustrate this approach by
implementing these interactions in brownian dynamics simulations of a strongly
confined electrolyte, and show that the resulting ionic conduction can be
adjusted between Ohm's law and a Wien effect behavior. Our results provide a
quantitative approach to tuning nanoscale ion transport through the electronic
properties of the channel wall material
Quantum feedback at the solid-liquid interface: flow-induced electronic current and negative friction
An electronic current driven through a conductor can induce a current in
another conductor through the famous Coulomb drag effect. Similar phenomena
have been reported at the interface between a moving fluid and a conductor, but
their interpretation has remained elusive. Here, we develop a
quantum-mechanical theory of the intertwined fluid and electronic flows, taking
advantage of the non-equilibrium Keldysh framework. We predict that a globally
neutral liquid can generate an electronic current in the solid wall along which
it flows. This hydrodynamic Coulomb drag originates from both the Coulomb
interactions between the liquid's charge fluctuations and the solid's charge
carriers, and the liquid-electron interaction mediated by the solid's phonons.
We derive explicitly the Coulomb drag current in terms of the solid's
electronic and phononic properties, as well as the liquid's dielectric
response, a result which quantitatively agrees with recent experiments at the
liquid-graphene interface. Furthermore, we show that the current generation
counteracts momentum transfer from the liquid to the solid, leading to a
reduction of the hydrodynamic friction coefficient through a quantum feedback
mechanism. Our results provide a roadmap for controlling nanoscale liquid flows
at the quantum level, and suggest strategies for designing materials with low
hydrodynamic friction
Exact numerical solution of the classical and quantum Heisenberg spin glass
We present the mean field solution of the quantum and classical Heisenberg
spin glasses, using the combination of a high precision numerical solution of
the Parisi full replica symmetry breaking equations and a continuous time
Quantum Monte Carlo. We characterize the spin glass order and its low-energy
excitations down to zero temperature. The Heisenberg spin glass has a rougher
energy landscape than its Ising analogue, and exhibits a very slow temperature
evolution of its dynamical properties. We extend our analysis to the doped,
metallic Heisenberg spin glass, which displays an unexpectedly slow spin
dynamics reflecting the proximity to the melting quantum critical point and its
associated Sachdev-Ye-Kitaev Planckian dynamics
Collective modes and quantum effects in two-dimensional nanofluidic channels
Nanoscale fluid transport is typically pictured in terms of atomic-scale dynamics, as is natural in the real-space framework of molecular simulations. An alternative Fourier-space picture, that involves the collective charge fluctuation modes of both the liquid and the confining wall, has recently been successful at predicting new nanofluidic phenomena such as quantum friction and near-field heat transfer, that rely on the coupling of those fluctuations. Here, we study the charge fluctuation modes of a two-dimensional (planar) nanofluidic channel. Introducing confined response functions that generalize the notion of surface response function, we show that the channel walls exhibit coupled plasmon modes as soon as the confinement is comparable to the plasmon wavelength. Conversely, the water fluctuations remain remarkably bulk-like, with significant confinement effects arising only when the wall spacing is reduced to 7 Ă
. We apply the confined response formalism to predict the dependence of the solidâwater quantum friction and thermal boundary conductance on channel width for model channel wall materials. Our results provide a general framework for Coulomb interactions of fluctuating matter under nanoscale confinement
Effets à N corps dans le transport de fluides aux nanoéchelles
This thesis explores several phenomena that arise in nanoscale fluid transport due to inter-particle correlations. We show that in nanoscale channels, the walls affect not only the fluid motion, but also its interactions. As a result, we predict enhanced ionic correlations in confined electrolytes, with consequences ranging from ionic Cou- lomb blockade to memory effects. We further explore how correlations between interfacial water and electron dynamics in the channel wall result in a quantum contribution to hydrodynamic friction. Finally, we present the development of an experimental setup for measuring water flow through two-dimensional channels.Cette thĂšse explore plusieurs phĂ©nomĂšnes de transport de fluides aux nanoĂ©chelles qui rĂ©sultent de corrĂ©lations entre les particules. Nous montrons que dans un canal nanomĂ©trique, les parois affectent non seulement le mouvement du fluide, mais aussi ses interactions. Ainsi, nous prĂ©disons des corrĂ©lations ioniques renforcĂ©es dans les Ă©lectrolytes confinĂ©s, avec des consĂ©quences allant du blocage de Coulomb ionique aux effets de mĂ©moire. Nous explorons ensuite les corrĂ©lations entre la dynamique de lâeau interfaciale et des Ă©lectrons de la paroi solide, qui induisent une contribution quantique Ă la friction hydrodynamique. Enfin, nous prĂ©sentons le dĂ©veloppement dâun dispositif expĂ©rimental pour la mesure de flux dâeau dans des canaux bidimensionnels
Effets à N corps dans le transport de fluides aux nanoéchelles
This thesis explores several phenomena that arise in nanoscale fluid transport due to inter-particle correlations. We show that in nanoscale channels, the walls affect not only the fluid motion, but also its interactions. As a result, we predict enhanced ionic correlations in confined electrolytes, with consequences ranging from ionic Coulomb blockade to memory effects. We further explore how correlations between interfacial water and electron dynamics in the channel wall result in a quantum contribution to hydrodynamic friction. Finally, we present the development of an experimental setup for measuring water flow through two-dimensional channels.Cette thĂšse explore plusieurs phĂ©nomĂšnes de transport de fluides aux nanoĂ©chelles qui rĂ©sultent de corrĂ©lations entre les particules. Nous montrons que dans un canal nanomĂ©trique, les parois affectent non seulement le mouvement du fluide, mais aussi ses interactions. Ainsi, nous prĂ©disons des corrĂ©lations ioniques renforcĂ©es dans les Ă©lectrolytes confinĂ©s, avec des consĂ©quences allant du blocage de Coulomb ionique aux effets de mĂ©moire. Nous explorons ensuite les corrĂ©lations entre la dynamique de lâeau interfaciale et des Ă©lectrons de la paroi solide, qui induisent une contribution quantique Ă la friction hydrodynamique. Enfin, nous prĂ©sentons le dĂ©veloppement dâun dispositif expĂ©rimental pour la mesure de flux dâeau dans des canaux bidimensionnels
Many-body effects in nanoscale fluid transport
Cette thĂšse explore plusieurs phĂ©nomĂšnes de transport de fluides aux nanoĂ©chelles qui rĂ©sultent de corrĂ©lations entre les particules. Nous montrons que dans un canal nanomĂ©trique, les parois affectent non seulement le mouvement du fluide, mais aussi ses interactions. Ainsi, nous prĂ©disons des corrĂ©lations ioniques renforcĂ©es dans les Ă©lectrolytes confinĂ©s, avec des consĂ©quences allant du blocage de Coulomb ionique aux effets de mĂ©moire. Nous explorons ensuite les corrĂ©lations entre la dynamique de lâeau interfaciale et des Ă©lectrons de la paroi solide, qui induisent une contribution quantique Ă la friction hydrodynamique. Enfin, nous prĂ©sentons le dĂ©veloppement dâun dispositif expĂ©rimental pour la mesure de flux dâeau dans des canaux bidimensionnels.This thesis explores several phenomena that arise in nanoscale fluid transport due to inter-particle correlations. We show that in nanoscale channels, the walls affect not only the fluid motion, but also its interactions. As a result, we predict enhanced ionic correlations in confined electrolytes, with consequences ranging from ionic Coulomb blockade to memory effects. We further explore how correlations between interfacial water and electron dynamics in the channel wall result in a quantum contribution to hydrodynamic friction. Finally, we present the development of an experimental setup for measuring water flow through two-dimensional channels
Modeling of emergent memory and voltage spiking in ionic transport through angstrom-scale slits
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