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Trabajo presentado en la 3rd Conference on Statistical Physics (2021), celebrada en Miramare (Italia) del 8 al 10 de septiembre de 2021., The stochastic nature of games at the casino allows lucky players to make profit by means of gambling. Like games of chance and stocks, small physical systems are subject to fluctuations, thus their energy and entropy become stochastic, following an unpredictable evolution. In this context, information about the evolution of a thermodynamic system can be used by Maxwell's demons to extract work using feedback control. This is not always the case, and a challenging task is then to develop efficient thermodynamic protocols achieving work extraction in situations where feedback control cannot be realized, in the same spirit as it is done on a daily basis in casinos and financial markets. We introduce and realize gambling demons who, following a customary gambling strategy to stop a nonequilibrium process at stochastic times, are able to extract more average work than the free energy change. We derive second laws in the presence of gambling, and a set of universal stopping-time fluctuation relations for the work done in classical and quantum stochastic non-stationary processes. We test experimentally our results in a single-electron box, where an electrostatic potential is used to drive the dynamics of individual electrons tunneling into a metallic island.

In this work we aim to analyze the effect of a strong antisymmetric spin-orbit coupling (ASOC) on the superconductivity of noncentrosymmetric LaPtSi. We study the energy gap structure of polycrystalline LaPtSi by using magnetic penetration depth measurements down to 0.02T c. We observed a dirty s-wave behavior, which provides compelling evidence that the spin-singlet component of the mixed pairing state is highly dominant. This is consistent with previous results in the sense that the mere presence of a strong ASOC does not lead to unconventional behaviors. Our result also downplays LaPtSi as a good candidate for realizing time-reversal invariant topological superconductivity.

In most strongly correlated electron systems superconductivity appears nearby a magnetic quantum critical point (QCP) which is believed to cause unconventional behaviors. In order to explore this physics, we present here a study of the heavy-fermion superconductors ${\mathrm{CeIrSi}}_{3}$ and ${\mathrm{CeRhSi}}_{3}$ carried out using a newly developed system for high-resolution magnetic penetration-depth measurements under pressure. Superconductivity in ${\mathrm{CeIrSi}}_{3}$ shows a change from an excitation spectrum with a line-nodal gap to one which is entirely gapful when pressure is close but not yet at the QCP. In contrast, ${\mathrm{CeRhSi}}_{3}$ does not possess a $T=0$ quantum phase transition and the superconducting phase remains for all accessible pressures with a nodal gap. Combining both results suggests that in these compounds unconventional superconducting behaviors are rather connected with the coexisting antiferromagnetic order. This study provides another viewpoint on the interplay of superconductivity, magnetism, and quantum criticality in ${\mathrm{CeIrSi}}_{3}$ and ${\mathrm{CeRhSi}}_{3}$ and maybe in other heavy fermions.

Superconductivity in noncentrosymmetric LaNiC$_2$ is expected to be induced by electron--phonon interactions due to its lack of magnetic instabilities. The non-Bardeen-Cooper-Schrieffer (BCS) behaviors found in this material call into question the long-standing idea that relates unconventional superconductivity with magnetic interactions. Here we report magnetic penetration-depth measurements in a high-purity single crystal of LaNiC$_2$ at pressures up to 2.5 GPa and temperatures down to 0.04 K. At ambient pressure and below 0.5$T_c$ the penetration depth goes as $T^4$ for the in-plane and $T^2$ for the out-of-plane component, firmly implying the existence of point nodes in the energy gap and the unconventional character of this superconductor. The present study also provides first evidence of magnetism in LaNiC$_2$ by unraveling a pressure-induced antiferromagnetic phase inside the superconducting state at temperatures below 0.5 K, with a quantum critical point around ambient pressure. The results presented here maintain a solid base for the notion that unconventional superconductivity only arises near magnetic order or fluctuations., Comment: 12 pages, 4 figures

The additament of an impurity to a metal matrix generates a shift in the local electron density of states due to a change in the local electric potential so that an electron or electron beam will be scattered upon interaction with the ensuing potential, causing its wave function measured at a distance far removed from the source to show a quantum phase change. This phenomenon, reflected in Friedel's law, permits to relate the quantum phase shifts with both the density of states at the Fermi level and the transport properties of the system. This work calculates the electric resistivity of nanometric clusters in an aluminiumsupercell, emulating the formation of Guinier-Preston zones during pre-precipitation in an Al-Zn alloy. The density of states is evaluated each time a new atom of solute is added to the Al supercell using the ab initio method of the Density Functional Theory or DFT in its GGA and LDA approximations via the Dmol^{3} package of Materials Studio Software. A resistivity anomaly is obtained when, in concordance with literature reports for diluted AlZn alloys, the supercell contains 25 atoms, thus confirming that the electric resistivity anomaly during cluster formation is a consequence of both density of states variations and quantum transitions at the Fermi Level for a nanometric size in particular. The results are contrasted with those obtained via the transport equation.

We measured the temperature dependence of the magnetic penetration depth of La3Pd4Si4 down to 0.02 Tc. We observe a temperature-independent behaviour below 0.25 Tc, which is firm evidence for a nodeless superconducting gap in this material. The data display a very small anomaly around 1 K which we attribute to the possible presence of a superconducting impurity phase. The superfluid density is well described by a two-phase model, considering La3Pd4Si4 and the impurity phase. The present analysis suggests that the superconducting energy gap of La3Pd4Si4 is isotropic, as expected for conventional BCS superconductors.

Prevention of Emulsion Formation During Matrix Acid Stimulation Jobs Using A Multi-Node Injection System and a pH Buffering Complex. Abstract A perennial problem during matrix acid stimulation jobs is the prevention of emulsion formation during pumping of the acid treatment downhole and during flowback of the spent acid returns up the wellbore and through the production facilities to the storage tanks. The presence of emulsion commingled with crude oil in the storage tanks decreases the volume of the crude oil available for sale and also affects the logistics of storage tank volume available for incoming crude oil. During normal non-acid production periods, various chemicals are routinely injected both at the production platform and the fluid collection, separation and storage terminal. However, during the flowback of spent acid returns from matrix stimulation jobs, the tendency of emulsion formation from the wellbore to the terminal is extremely enhanced and very sensitive to certain system parameters. If the system parameters are not fully understood and controlled, the result of emulsion formation is invariably catastrophic. This paper presents the results of three years of study into the subject of emulsion prevention and control during matrix acid stimulation jobs in the Teak, Poui and Samaan fields, offshore Trinidad. The salient system parameters from the wellbore to the terminal which affect emulsion formation are presented. A unique Multi-Node Fluid Injection System, developed and utilized in Trinidad for the total control of the system parameters is also presented. Another aspect of this paper is the discovery, by the authors, of the application of a pH Buffering Complex to provide the ultimate method (to date) to control the formation of emulsion along the production system. The combination of the Multi-Node Fluid Injection System. and the pH Buffering Complex offers the best solution to date for the prevention and control of emulsion formation during matrix acid stimulation jobs. Introduction The Teak A, Poui A and Sarun A production platforms are approximately 40 km, 19 km and 45 km respectively off the South East coast of Trinidad. The Teak A production platform processes oil produced from five (5) platforms in the field. The Samaan A platform processes oil from three (3) platforms and the Poui A facilities from two (2) platforms. After acid stimulation jobs, severe emulsion problems can occur at the production facilities, both offshore and at the tank farm, Galeota Point, Trinidad. Offshore, the difficulty in fluid separation resulted in extreme work scheduling on the production pumps and in some cases, environmental concerns with the dumping of water overboard. At the Galeota Point base operations, the problem could result in thousands of barrels of oil being "tied-up" in the form of emulsions in the storage tanks, which affects crude oil sales and shipment. Test samples taken from the production system showed that in some cases emulsions were being produced from the well. in some cases, the degree of emulsion decreased upon neutralization. In other cases, the quantity of emulsion increased or actually developed upon neutralizing. In all cases, spent acid returns were neutralize using Soda Ash or Caustic Soda solution. Typical spent acid returns consisted of o to 3 percent HCl acid. P. 391