Effect Of Thermal Fluctuations Research Articles

Effect of thermal fluctuation on the thermodynamics of GMGHS black hole

In present paper we discuss the effect of higher order corrections of entropy on the thermodynamic fluctuation of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole (GMGHS), i.,e. charged diatonic black hole. By investigating the thermodynamic property functions, such as the internal energy, the enthalpy, the Helmholtz free energy, the Gibbs free energy and the heat capacity, we find that the correction from the thermodynamic fluctuation is very important for small black hole case and one can neglect the correction for large black hole case. We also find that when there is no thermal fluctuation, this black hole thermodynamic system acts as an ideal gas state. However when we consider the thermal fluctuation, we can see the Van der waals type behavior in GMGHS black hole system. Finally, we discuss the stability of GMGHS black hole by investigating the behaviour of heat capacity under effect of thermal fluctuation, we find that, without any thermal fluctuation, we get the completely unstable black hole. However, with the presence of thermal fluctuation, the black hole becomes stable at smaller value of horizon radius, also there is a stable to unstable phase transition from the corrected specific heat.

Conformational control over π-conjugated electron pairing in 1D organic polymers.

During the past decades π-conjugated bi-radicals have attracted increasing attention, due to the existence of two close-in-energy resonant electronic configurations with very distinct characteristics: the open-shell bi-radical and the closed-shell quinoidal. The chemical design of the bi-radical structure has been shown to be very effective to shift the balance towards one, or the other, electronic distribution. Some reports have experimentally studied the analogous 1D oligomers and polymers, however, only the open-shell multi-radical configuration has been detected, and it is yet not very clear which structural and chemical parameters are relevant in such extended systems. In this work, via first principles quantum chemical simulations, we study a series of π-conjugated 1D polymers based on triarylmethyl radicals with different chemical functionalization. We find that dihedral angles of the aryl rings connecting the radical centres are the key conformational parameter determining the electronic balance. This provides a simple recipe to use chemical functionalization of aryl rings as a tool to shift the system towards either the electron paired or unpaired configurations. Additionally, we find such conformational control is also effective under the effect of thermal fluctuations, which highlights its potential technological applicability.

Rotor Jackiw-Rebbi Model: A Cold-Atom Approach to Chiral Symmetry Restoration and Charge Confinement

Understanding the nature of confinement, as well as its relation with the spontaneous breaking of chiral symmetry, remains one of the long-standing questions in high-energy physics. The difficulty of this task stems from the limitations of current analytical and numerical techniques to address non-perturbative phenomena in non-Abelian gauge theories. In this work, we show how similar phenomena emerge in simpler models, and how these can be further investigated using state-of-the-art cold-atom quantum simulators. More specifically, we introduce the rotor Jackiw-Rebbi model, a (1+1)-dimensional quantum field theory where interactions between Dirac fermions are mediated by quantum rotors. Starting from a mixture of ultracold atoms in an optical lattice, we show how this quantum field theory emerges in the long-wavelength limit. For a wide and experimentally-relevant parameter regime, the Dirac fermions acquire a dynamical mass via the spontaneous breakdown of chiral symmetry. Moreover, we study the effect of both quantum and thermal fluctuations, which lead to the phenomenon of chiral symmetry restoration. Finally, we uncover a confinement-deconfinement quantum phase transition, where meson-like fermions fractionalise into quark-like quasi-particles bound to topological solitons of the rotor field. The proliferation of these solitons at finite chemical potentials again serves to restore the chiral symmetry, yielding a clear analogy with the quark-gluon plasma in quantum chromodynamics, where this symmetry coexists with the deconfined fractional charges. Our results show how the interplay between these phenomena could be analyse in realistic atomic experiments.

Thermodynamics of dilute Bose gases: Beyond mean-field theory for binary mixtures of Bose-Einstein condensates

We study the thermodynamic properties of binary Bose mixtures, by developing a beyond mean-field Popov theory which properly includes the effects of quantum and thermal fluctuations in both the density and spin channels. Results for key thermodynamic quantities, such as the isothermal compressibility and the magnetic susceptibility, are derived from a perturbative calculation of the grand-canonical potential. We find that thermal fluctuations can play a crucial role on the miscibility condition of a binary mixture, favoring phase separation at finite temperature even if the mixture is soluble at zero temperature, as already anticipated in a previous work [Ota et al., Phys. Rev. Lett. 123, 075301 (2019)]. We further investigate the miscibility condition for binary mixtures in the presence of asymmetry in the intra-species interactions, as well as in the masses of the two components. Furthermore, we discuss the superfluid behavior of the mixture and the temperature dependence of the Andreev-Bashkin effect.

Strong-coupling effects of pairing fluctuations, and Anderson-Bogoliubov mode in neutron S01 superfluids in neutron stars

We investigate effects of thermal and quantum fluctuations of the superfluid order parameter in $^1S_{0}$ superfluids in neutron stars. We construct a separable potential to reproduce the $^1S_{0}$ phase shift reconstructed by using the partial wave analysis from nucleon scattering data. We include superfluid fluctuations within a strong-coupling approximation developed by Nozi\`eres and Schmitt-Rink and determine self-consistently the superfluid order parameter as well as the chemical potential. We show that the quantum depletion, which gives a fraction of noncondensed neutrons at zero temperature due to quantum pairing fluctuations, plays an important role not only near the critical temperature from superfluid states to normal states but also at zero temperature. We derive the dispersion relation of Anderson-Bogoliubov modes associated with phase fluctuations, and show also that there is a nonzero fraction of noncondensed components in the neutron number as a result of the strong-coupling effect. Our results indicate that superfluid fluctuations are important for thermodynamic properties in neutron stars.

The effects of nonlinear thermal fluctuation and series junction array on high-T c superconducting terahertz mixer performance

Sensitive high-T c superconducting (HTS) heterodyne receivers are envisioned as promising technologies for terahertz (THz) communication and sensing applications due to the lack of power efficient sources in the band. HTS device properties, particularly the noise temperature, are dependent on complicated factors that include multiple noise sources as well as the interaction between Josephson junction and radio-frequency (RF) networks. We report investigations on the device properties of an HTS THz mixer in the presence of nonlinear thermal fluctuation and series junction array. By using the three-port analysis method, it is observed that the Planck and quantum noises representing nonlinear thermal fluctuation plays a significant role in the cases of smaller fluctuation parameters and higher signal frequencies. The influence of series junction array on mixer performance is also studied, which shows that there is an optimum junction number dependent on the normalized RF source impedance. The measured results of a broadband antenna-coupled HTS single-junction mixer agree well with that obtained by numerical simulation. The results predict that noise performance, conversion gain and operating bandwidth would be considerably improved if a series junction array with a suitable junction number is used for heterodyne mixing.

Nanoscale thin-film flows with thermal fluctuations and slip.

The combined effects of thermal fluctuations and liquid-solid slip on nanoscale thin-film flows are investigated using stochastic lubrication equations (SLEs). The previous no-slip SLE for films on plates is extended to consider slip effects and a new SLE for films on fibers is derived, using a long-wave approximation to fluctuating hydrodynamics. Analytically derived capillary spectra, which evolve in time, are found from the new SLEs and compared to molecular dynamics simulations. It is shown that thermal fluctuations lead to the generation and growth of surface waves, and slip accelerates this growth. SLEs developed here provide useful tools to study nanoscale film dewetting, nanofiber coating, and liquid transport using nanofibers.

Study of thermal fluctuations in a charged rotating accelerating AdS black hole

In this paper, we study the effects of thermal fluctuations on thermodynamics of charged rotating and accelerating anti-de Sitter black hole. We first derive exact expressions of thermodynamic quantities such as entropy, Hawking temperature and angular velocity for slowly accelerating black hole. We then compute Smarr–Gibbs–Dehum relation and thermodynamical volume in extended phase space. To discuss the impact of quantum fluctuations, we evaluate leading-order correction terms to entropy which modify other thermodynamical equations of state. Finally, we calculate specific heat to examine the local stability of this black hole. It is found that the logarithmic corrections originated from thermal fluctuations induce instability to small black holes.

Structural phase transition of the ion crystals embedded in an optical lattice

The structural phase transition (SPT) occurring in trapped-ion systems is a typical many-body physics, and the SPT induced by the thermal effect represents a special thermodynamic phenomenon between traditional thermodynamics and quantum thermodynamics. We explore this thermal-effect-induced SPT by embedding trapped $^{40}\mathrm{Ca}^{+}$ ion crystals in an optical lattice, in which the ion crystals are confined by a surface-electrode trap and laser-cooled down to a temperature of several millikelvins. The considered thermal effect, leading to a temperature variation of tens of microkelvins in the SPT, comes completely from the optical lattice, which is independent of the laser irradiation regarding cooling of the ion crystals. In comparison with previous work [J. Li et al., Phys. Rev. A 99, 063402 (2019)], the present investigation helps to further clarify the effect of thermal fluctuation and further explore the positive role of the fluctuation in thermodynamics at the atomic level, even for potentially practical applications.

A review on recent research studies on vibration analysis of fluid-conveying nanotubes

Nanotube (such as carbon and boron nitride nanotubes) is a key component of modern technology applications of nanostructures due to their unique mechanical, electrical, and physical characteristics such as high elasticity modulus, suitable heat transfer, and electrical conductivity. Carbon and boron nitride nanotubes are among the promising choices in nano-fluidic, gas storage, and drug delivery systems due to their hollow cylindrical shape and appropriate chemical, mechanical, and physical properties. Thermal vibration assessment should be conducted on fluid-conveying carbon nanotubes since the effect of thermal fluctuations on the mechanical characteristics of nanostructure are significant. Previous studies have revealed that when thermal vibration is taken into account, quantum effects can become extremely important in nanoscale electronics and structures. Hence, the present review focuses mostly on previous work on fluid-conveying nanotubes and the dynamical characteristics of size-dependent vibration and non-local strain gradient theory of fluid-conveying nanotubes. Furthermore, a special effort is made to address recent and rare investigations on the vibration of fluid-conveying nanotubes in thermal environment, as well as thermal vibration concerns of carbon nanotubes.

Investigation of Post-Bond Distortion in Direct Wafer Bonding

As device sizes continue to shrink, accurate alignment in semiconductor wafer bonding process becomes more important. In the case of two patterned wafers directly bonded together, proper alignment of the electrical connections between the two bonding surfaces is critical. Misalignment between the wafers during bonding may lead to degraded electrical performance or even device failure. In the case of a patterned wafer directly bonded onto a blank carrier wafer, the relative displacement along the bonded interface is important for subsequent steps. This relative displacement contributes to overlay error in lithography steps. Furthermore, as device density continues to increase, pre-bond wafer shapes become more complex while warp magnitude increases. The distortion contribution from pre-bond wafer shapes becomes more significant as a result. Therefore, it is important to understand the direct wafer bonding distortion mechanics to reduce the yield impact of the process.This paper develops a mechanics model to study wafer bonder performance. An axisymmetric solid mechanics model simulates the wafer bonding dynamics by using a rate-dependent adhesion model. This simulation model includes calibration parameters to tune against experimental results. Using the optimized calibration parameters, an extended 3D simulation model studies more complex phenomena. This paper will report the simulation results that include local variations in wafer properties, clamping and thermal fluctuation effects. Distortion impact due to pre-bond wafer shapes, such as the relative contributions from the pre-bond wafer pair, is also discussed.The results of this model can enable improved hardware optimization to address stricter distortion requirements. This model can optimize key hardware features in lieu of large number of wafer tests to minimize the cost of development. Using this model, target performance can be achieved with fewer hardware iterations and reduce development time. Bonder recipes can also be designed and optimized to account for pre-bond wafer characteristics.

Phase transition and thermal fluctuations of quintessential Kerr–Newman–AdS black hole

This paper is devoted to analyzing the critical phenomenon and phase transition of quintessential Kerr–Newman-anti-de Sitter black hole in the framework of Maxwell equal-area law. For this purpose, we first derive thermodynamic quantities such as Hawking temperature, entropy and angular momentum in the context of extended phase space. These quantities satisfy Smarr–Gibbs–Dehum relation in the presence of quintessence matter. We then discuss the critical behavior of thermodynamic quantities through two approaches, i.e., van der Waals-like equation of state and Maxwell equal-area law. It is found that the latter approach is more effective to analyze the critical behavior of the complicated black holes. Using equal-area law, we also study phase diagram in T – S plane and find an isobar which shows the coexistence region of two phases. We conclude that below the critical temperature, black holes show a similar phase transition as that of van der Waals fluid. Finally, we study the effects of thermal fluctuations on the stability of this black hole.

Rupture process of liquid bridges: The effects of thermal fluctuations.

Rupture of a liquid bridge is a complex dynamic process, which has attracted much attention over several decades. We numerically investigated the effects of the thermal fluctuations on the rupture process of liquid bridges by using a particle-based method know as many-body dissipative particle dynamics. After providing a comparison of growth rate with the classical linear stability theory, the complete process of thinning liquid bridges is captured. The transitions among the inertial regime (I), the viscous regime (V), and the viscous-inertial regime (VI) with different liquid properties are found in agreement with previous work. A detailed description of the thermal fluctuation regime (TF) and another regime, named the breakup regime, are proposed in the present study. The full trajectories of thinning liquid bridges are summarized as I→V→VI→TF→ breakup for low-Oh liquids and V→I→ Intermediate →V→VI→TF→ breakup for high-Oh liquids, respectively. Moreover, the effects of the thermal fluctuations on the formation of satellite drops are also investigated. The distance between the peaks of axial velocity is believed to play an important role in forming satellite drops. The strong thermal fluctuations smooth the distribution of axial velocity and change the liquid bridge shape into a double cone without generating satellite drops for low-Oh liquids, while for high-Oh liquids, this distance is extended and a large satellite drop is formed after the breakup of the liquid filament occurs on both ends, which might be due to strong thermal fluctuations. This work can provide insights on the rupture mechanism of liquid bridges and be helpful for designing superfine nanoprinting.

Fluctuating temperatures extend median lifespan, improve reproduction and reduce growth in turquoise killifish.

In natural populations, individuals experience daily fluctuations in environmental conditions that synchronise endogenous biorhythms. Artificial alterations of environmental fluctuations can have negative consequences for life history traits, including lifespan. In laboratory studies of aging, the role of fluctuating temperature is usually overlooked and we know little of how thermal fluctuation modulates senescence in vertebrates. In this longitudinal study we followed individually-housed turquoise killifish, Nothobranchius furzeri, from two thermal regimes; ecologically relevant diel fluctuations (20 °C - 35 °C) and stable temperature (27.5 °C), and compared their survival, growth and reproduction. Fish experiencing fluctuating temperatures had a longer median lifespan but reached smaller asymptotic body size. Within-treatment variation indicated that extended lifespan in fluctuating temperatures was not causally linked to decreased growth rate or smaller body size, but occurred solely due to the effect of thermal fluctuations. Male body size was positively associated with lifespan in stable temperatures but this relationship was disrupted in fluctuating thermal regimes. Females exposed to fluctuating temperatures effectively compensated egg production for their smaller size. Thus, there was no difference in absolute fecundity between thermal regimes and body-size corrected fecundity was higher in females in fluctuating temperatures. Overall, despite a brief exposure to sub-optimal thermal conditions during fluctuations, fluctuating temperature had a positive effect on survival and reproduction. These results suggest that the expression of life history traits and their associations under stable temperatures are a poor representation of the relationships obtained from ecologically relevant thermal fluctuations.

Reliability Assessment of Solder Joints in Electronic Devices Under Extreme Thermal Fluctuations

In this work, the effects of extreme thermal fluctuations on the reliability of solder joints were investigated. For this purpose, the solder joints in insulated-gate bipolar transistor (IGBT) devices were exposed to the conventional thermal cycling and the thermal shock cycling (TSC) tests. The finite element method (FEM) simulation results indicated that the accumulated creep energy in solder layer is much higher under the TSC process. Moreover, the stress triaxiality, as the indicator of damage initiation, is more concentrated in the TSC-exposed sample. It is believed that the higher heating and cooling rates along with the higher peak temperatures lead to the damage susceptibility of solder joints under TSC process. The experimental results confirm that the void formation and growth significantly increases in the TSC-exposed sample, which is consistent with the simulation outcomes. Moreover, the shear test reveals that the ultimate strength of sample under the thermal shocking severely decreases which is due to the void growth and the intensified elemental heterogeneity.

Finite temperature effects in quantum systems with competing scalar orders

The study of the competition or coexistence of different ground states in many-body systems is an exciting and actual topic of research, both experimentally and theoretically. Quantum fluctuations of a given phase can suppress or enhance another phase depending on the nature of the coupling between the order parameters, their dynamics and the dimensionality of the system. The zero temperature phase diagrams of systems with competing scalar order parameters with quartic and bilinear coupling terms have been previously studied for the cases of a zero temperature bicritical point and of coexisting orders. In this work, we apply the Matsubara summation technique from finite temperature quantum field theory to introduce the effects of thermal fluctuations on the effective potential of these systems. This is essential to make contact with experiments. We consider two and three-dimensional materials characterized by a Lorentz invariant quantum critical theory, i.e., with dynamic critical exponent z = 1, such that time and space scale in the same way. We obtain that in both cases, thermal fluctuations lead to weak first-order temperature phase transitions, at which coexisting phases arising from quantum corrections become unstable. We show that above this critical temperature (Tc), the system presents scaling behavior consistent with that approaching a quantum critical point. Below the transition the specific heat has a thermally activated contribution with a gap related to the size of the domains of the ordered phases. We obtain that Tc decreases as a function of the distance to the zero temperature classical bicritical point (ZTCBP) in the coexistence region, implying that in our approach, the system attains the highest Tc above the fine tuned value of this ZTCBP.

Cooling a Mechanical Oscillator in Opto-electro-mechanical System with Frequency Modulations

The opto-electro-mechanical system as a quantum interface between electronic information and optical information plays an important role in quantum information processing. Ground-state cooling of the macroscopic mechanical oscillator is a crucial requirement for this system in order to eliminate the effect of thermal fluctuations on transmission of information. Here, we propose a scheme of ground-state cooling for a mechanical oscillator which is coupled to an optical cavity through radiation pressure force and simultaneously coupled to a superconducting microwave cavity through an effective capacitance. Meanwhile, the periodical frequency modulations are applied to the optical mode, microwave cavity, and mechanical mode, respectively. The cooling efficiency is analyzed and cooling dynamics is simulated numerically by means of covariance matrix. The results show that the Stokes heating processes can be suppressed effectively by means of frequency modulations, and the mechanical oscillator can be cooled to near its ground-state with a higher efficiency than that of a standard optomechanical system due to the double cooling channel. Moreover, a complementary cooling effect is found between these two cooling channels, i.e., a high cooling efficiency can be achieved by cooperation between a good optical cavity and a bad microwave cavity, or vice versa. This cooperative cooling of the double channel breaks the limitation of resolved-sideband regime.

Deformation of a Liquid Near an AFM Tip: Molecular Dynamics Approach.

The interaction between an atomic force microscopy (AFM) probe and a thin film of water deposited over a flat substrate is studied using molecular dynamics (MD). The effects of the film thickness and the probe radius on both the deformation height of the liquid interface and the distance of the jump to contact at which the liquid comes in direct contact with the probe are investigated. The dynamics of the surface deformation and the role of interface fluctuations are studied in detail. The systems considered belong to the thin-film regime described in a semianalytical model previously established by Ledesma-Alonso et al. (Langmuir 2013, 29, 7749-7757). MD simulations predict that for shallow films, both the distance at which the jump to contact occurs and the surface maximal deformation height increase steadily with the layer thickness regardless of the probe radius, which is in agreement with the previously proposed theoretical model. The deformation of the surface was shown to be unstable because of the strong effect of thermal fluctuations. For each of the considered systems, the film thickness was such that interface fluctuations induced the jump to contact. The comparison of the deformation obtained in MD with the profiles predicted by the continuous model points out the complementarity between the two approaches. The results of the molecular approach not only are consistent with those of the continuous model but also provide more information on the description of nanoscale phenomena. In particular, MD results point out the importance of fluctuations when it comes to the description of the particular dynamics of nanosystems involving soft interfaces. This shows the need to improve continuous models by complementing them with a molecular approach for a better accuracy.

Colorimetry characterization of molecular reorientation transition in thin nematic cells.

The characterization of equilibria and their transition is fundamental in dynamic systems. Experimentally, the characterization of transitions is complex due to time scales separation, the effect of thermal fluctuations, and inherent experimental imperfections. Liquid crystal devices are derived from the manipulation of the molecular reorientation and transition between them by employing external electrical and magnetic fields. Here, we investigate and determine the Fréedericksz transition using hue measurements of the transmitted light in thin nematic liquid crystal cells. Based on birefringent retardation experienced by transmitted light due to molecular reorientation, the color adjustment of the nematic liquid crystal cells under white light illumination is characterized. By monitoring the hue of the transmitted light, the bifurcation diagram is determined. As a function of the voltage frequency, the critical transition voltage is characterized. The critical voltage increases with the applied frequency.

Quasi-normal modes and thermal fluctuations of charged black hole with Weyl corrections

Abstract In this paper, we study thermodynamics, quasi-normal modes and thermal fluctuations of a charged black hole with Weyl corrections. We first obtain thermodynamic quantities such as Hawking temperature, entropy, and heat capacity for non-rotating as well as rotating versions of this black hole. We also evaluate temperature through quantum tunneling mechanism which is exactly the same as found through surface gravity. We then discuss the relation between Davies point and quasi-normal modes. Finally, we investigate the effects of thermal fluctuations on the uncorrected thermodynamic quantities. It is concluded that the logarithmic corrections originated from thermal fluctuations make the system more unstable for small BHs.