Related papers: Superfluidity of Dense $^4$He in Vycor
$^4$He nanodroplets doped with an alkali ion feature a snowball of crystallized layers surrounded by superfluid helium. For large droplets, we predict that a transitional supersolid layer can form, bridging between the solid core and the…
We present a zero-temperature quantum Monte Carlo calculation of liquid $^4$He immersed in an array of confining potentials. These external potentials are centered in the lattice sites of a fcc solid geometry and, by modifying their well…
Using quantum Monte Carlo we have studied the superfluid density of the first layer of $^4$He and H$_2$ adsorbed on graphene and graphite. Our main focus has been on the equilibrium ground state of the system, which corresponds to a…
Evidence for a new type of superfluid phase in second-layer $^4$He on graphite has been obtained from simultaneous measurements of torsional-oscillator response and heat-capacity on exactly the same sample down to 30 mK, which resolve…
The local environment and the energetic properties of one $^3$He atom solved in bulk superfluid $^4$He are studied by means of the diffusion Monte Carlo method. The chemical potential of the $^3$He impurity is calculated with a generalized…
Low temperature structural and superfluid properties of $^4$He confined in cylindrical nanopores are theoretically investigated by means of first principle Quantum Monte Carlo (QMC) simulations. We vary the density of $^4$He inside the…
We have performed a microscopic study of a straight quantized vortex line in three dimensions in condensed $^4$He at zero temperature using the Shadow Path Integral Ground State method and the fixed-phase approximation. We have…
We have studied the solubility of molecular hydrogen in bulk liquid $^4$He at zero temperature using the diffusion Monte Carlo method and realistic interatomic potentials between the different species of the mixture. Around the $^4$He…
The low temperature properties of solid $^4$He contained in porous Vycor glass have been investigated utilizing a two-mode compound torsional oscillator. At low temperatures, we find period shift signals for the solid similar to those…
Detailed numerical results obtained with state-of-the-art Quantum Monte Carlo (QMC) simulations are presented for the superfluid phase of $^4$He at saturated vapor pressure. The aim of this contribution is that of providing reliable,…
In a recent study we have reported a new type of trial wave function symmetric under the exchange of particles and which is able to describe a supersolid phase. In this work, we use the diffusion Monte Carlo method and this model wave…
We present a path integral Monte Carlo study of the global superfluid fraction and local superfluid density in cylindrically-symmetric reservoirs of liquid $^{4}$He separated by nanoaperture arrays. The superfluid response to both…
We revisited the phase diagram of the second layer of 4He on top of graphite using quantum Monte Carlo methods. Our aim was to explore the existence of the novel phases suggested recently in experimental works, and determine their…
We present a diffusion Monte Carlo study of a single vortex in two-dimensional superfluid liquid $^4$He within the fixed node approximation. We use both the Feynman phase and an improved phase which includes backflow correlations to model…
The second layer of $^4$He films adsorbed on a graphite substrate is an excellent experimental platform to study the interplay between superfluid and structural orders. Here, we report a rigid two-frequency torsional oscillator study on the…
Path Integral Monte Carlo calculations of the superfluid density throughout ^4He droplets doped with linear impurities (HCN)_n are presented. After deriving a local estimator for the superfluid density distribution, we find a decreased…
We present a microscopic theory of superfluid $^4$He, formulated using the overall experimental observations as input information. With the theory of a consistent basis, we answer all of the essential questions regarding He II.
We study the superfluid transition of $^4$He in aerogel by Monte Carlo simulations and finite size scaling analysis. Aerogel is a highly porous silica glass, which we model by a diffusion limited cluster aggregation model. The superfluid is…
By using the diffusion Monte Carlo method, we obtained the full phase diagram of $^3$He on top of graphite preplated with a solid layer of $^4$He. All the $^4$He atoms of the substrate were explicitly considered and allowed to move during…
The bound state of a He-3 atom at the interface between coexisting crystalline and superfluid phases of He-4 is studied theoretically by means of first principle Quantum Monte Carlo simulations. We consider both the case of a…