arXiv subjects

Hisao Hayakawa

Publications and source records attributed to Hisao Hayakawa.

At least 91 records · Page 5Linked to original sources

arXiv2014

Energetics of active fluctuations in living cells

The nonequilibrium activity taking place in a living cell can be monitored with a tracer embedded in the medium. While microrheology experiments based on optical manipulation of such probes have become increasingly standard, we put forward a number of experiments with alternative protocols that, we claim, will provide new insight into the energetics of active fluctuations. These are based on either performing thermodynamic--like cycles in control-parameter space, or on determining response to external perturbations of the confining trap beyond simple translation. We illustrate our proposals on an active itinerant Brownian oscillator modeling the dynamics of a probe embedded in a living medium.

cond-mat.soft↗

arXiv2014

Roles of Dry Friction in Fluctuating Motion of Adiabatic Piston

The motion of an adiabatic piston under dry friction is investigated to clarify the roles of dry friction in non-equilibrium steady states. We clarify that dry friction can reverse the direction of the piston motion and causes a discontinuity or a cusp-like singularity for velocity distribution functions of the piston. We also show that the heat fluctuation relation is modified under dry friction.

cond-mat.stat-mech↗

arXiv2013

Analytical expression of geometrical pumping for a quantum dot based on quantum master equation

We analytically investigate a non-equilibrium quantum pumping for a single quantum dot connected to external leads on the basis of the quantum master equation (QME). We show that the Coulomb interaction associated with the spin effect in the dot induces the Berry-like phase in the parameter space and this phase results in the excess charge transfer for the cyclic modulation of parameters in leads. We obtain an analytical expression of the curvature of the phase and that for the pumped currents.

cond-mat.mes-hall↗

arXiv2013

Effect of Elastic Vibrations on Normal Head on Collisions of Isothermal Spheres

We numerically investigate head on collisions of isothermal visco-elastic spheres. We find that the restitution coefficient oscillates against the impact speed if the solid viscosity inside the sphere is small enough. We confirm that the oscillation arises from the resonance between the duration of contact and the eigen-frequencies of the sphere. This oscillation disappears if there exists the strong solid viscosity in spheres. We also find that a sinusoidal behavior of the restitution coefficient against the initial phase in the eigenmodes for collisions between a thermally activated sphere and a flat wall. As a result, the restitution coefficient can exceed unity if the impact speed of the colliding sphere is nearly equal to or slower than the thermal speed. We have confirmed the existence of the fluctuation theorem for impact processes through our simulation.

cond-mat.stat-mech↗

arXiv2013

Nonequilibrium identities of granular vibrating beds

We derive the integral fluctuation theorem around a nonequilibrium stationary state for frictionless and soft core granular particles under an external vibration achieved by a balance between an external vibration and inelastic collisions. We also discuss the connection between the integral fluctuation theorem and the generalized Green-Kubo formula.

cond-mat.stat-mech↗

arXiv2013

Breakdown of a renormalized perturbation expansion around mode-coupling theory of the glass transition

We analyze a renormalized perturbation expansion around the mode-coupling theory of the glass transition. We focus on the long-time limit of the irreducible memory function. We discuss a renormalized diagrammatic expansion for this function and re-sum two infinite classes of diagrams. We show that the resulting contributions to the irreducible memory function diverge at the mode-coupling transition. A further re-summation of ladder diagrams constructed by iterating these divergent contributions gives a finite result which cancels the mode-coupling theory's expression for the irreducible memory function.

cond-mat.stat-mech↗

arXiv2013

Geometrical Excess Entropy Production in Nonequilibrium Quantum Systems

For open systems described by the quantum Markovian master equation, we study a possible extension of the Clausius equality to quasistatic operations between nonequilibrium steady states (NESSs). We investigate the excess heat divided by temperature (i.e., excess entropy production) which is transferred into the system during the operations. We derive a geometrical expression for the excess entropy production, which is analogous to the Berry phase in unitary evolution. Our result implies that in general one cannot define a scalar potential whose difference coincides with the excess entropy production in a thermodynamic process, and that a vector potential plays a crucial role in the thermodynamics for NESSs. In the weakly nonequilibrium regime, we show that the geometrical expression reduces to the extended Clausius equality derived by Saito and Tasaki (J. Stat. Phys. {\bf 145}, 1275 (2011)). As an example, we investigate a spinless electron system in quantum dots. We find that one can define a scalar potential when the parameters of only one of the reservoirs are modified in a non-interacting system, but this is no longer the case for an interacting system.

cond-mat.stat-mech↗

arXiv2013

The Legacy of Hideki Yukawa, Sin-itiro Tomonaga, and Shoichi Sakata: Some Aspects from their Archives

Hideki Yukawa, Sin-itiro Tomonaga and Shoichi Sakata pioneered nuclear and particle physics and left enduring legacies. Their friendly collaboration and severe competition laid the foundation to bring up the active postwar generation of nuclear and particle physicists in Japan. In this presentation we illustrate milestones of nuclear and particle physics in Japan from 1930's to mid-1940's which have been clarified in Yukawa Hall Archival Library, Tomonaga Memorial Room and Sakata Memorial Archival Library.

physics.hist-ph↗

arXiv2013

Nonequilibrium identities and response theory for dissipative particles

We derive some nonequilibrium identities such as the integral fluctuation theorem and the Jarzynski equality starting from a nonequilibrium state for dissipative classical systems. Thanks to the existence of the integral fluctuation theorem we can naturally introduce an entropy-like quantity for dissipative classical systems in far from equilibrium states. We also derive the generalized Green-Kubo formula as a nonlinear response theory for a steady dynamics around a nonequilibrium state. We numerically verify the validity of the derived formulas for sheared frictionless granular particles.

cond-mat.stat-mech↗

arXiv2013

Jet-induced jammed states of granular jet impacts

The impacts of granular jets for both frictional and frictionless grains in two dimensions are numerically investigated. A dense flow with a dead zone emerges during the impact. From our two-dimensional simulation, we evaluate the equations of state and the con- stitutive equations of the flow. The asymptotic divergences of pressure and shear stress similar to the situation near the jamming transition appear for the frictionless case, while their exponents are smaller than those of the sheared granular systems, and are close to the extrapolation from the kinetic theoretical regime. In a similar manner to the jam- ming for frictional grains, the critical density decreases as the friction constant of grains increases. For bi-disperse systems, the effective friction constant defined as the ratio of shear stress to normal stress, monotonically increases from near zero, as the strain rate increases. On the other hand, the effective friction constant has two metastable branches for mono-disperse systems because of the coexistence of a crystallized state and a liquid state.

cond-mat.stat-mech↗

arXiv2013

Heat conduction induced by non-Gaussian athermal fluctuations

We study the properties of heat conduction induced by non-Gaussian noises from athermal environments. We find that new terms should be added to the conventional Fourier law and the fluctuation theorem for the heat current, where its average and fluctuation are determined not only by the noise intensities but also by the non-Gaussian nature of the noises. Our results explicitly show the absence of the zeroth law of thermodynamics in athermal systems.

cond-mat.stat-mech↗

arXiv2013

Constitutive Relations of Jammed Frictionless Granular Materials under Oscillatory Shear

We numerically investigate the rheological properties of jammed frictionless granular materials under an oscillatory shear in terms of our simulation of the distinct element method. It is demonstrated that the constitutive relation between the shear stress and the shear strain of grains strongly depends on the amplitude and the frequency of the oscillatory shear. For a small amplitude region, the granular material behaves as a visco-elastic material characterized by the Kelvin-Voigt model, while it behaves as a yield stress liquid for a large amplitude region. We find that the rheology of grains under the large amplitude oscillatory shear can be described by a phenomenological constitutive model.

cond-mat.stat-mech↗

arXiv2013

Numerical analysis of impact processes of granular jets

The rheology of a three-dimensional granular jet during an impact is investigated numerically. The cone-like scattering pattern and the sheet-like pattern observed in an experiment [X. Cheng, et al. Phys. Rev. Lett. 99, 188001 (2007)] can be reproduced through our calculation. We discuss the constitutive equation for granular jet impact in terms of our simulation. From the analysis of an effective friction constant, which is the ratio between the shear stress and the pressure the assumption of the zero yield stress would be natural in our setup and the shear visocity is not small in contrast to the suggestion by the experiment.

cond-mat.soft↗

arXiv2013

Geometrical pumping in spin coupled double quantum dots

We analytically investigate the non-equilibrium pumping for a double quantum dots system on the basis of the quantum master equation (QME), where the double quantum dots are connected to two external leads by the spin coupling. Each of leads has two tunable parameters, temperature and chemical potential. Using QME formalism, we obtain an analytical expression of the Berry-like phase for eigenstate of the QME in the parameter space. We show that the Berry-like curvature is non zero in the whole region in the parameter space. We also show that the Berry-like curvature vanishes in the case of single quantum dot and the case of isolated two dots.

cond-mat.mes-hall↗

arXiv2013

Nonequilibrium mode-coupling theory for uniformly sheared underdamped systems

Mode-coupling theory for uniformly sheared underdamped systems with an isothermal condition is presented. As a result of the isothermal condition, it is shown that the shear stress exhibits significant relaxation at the alpha-relaxation regime due to the cooling effect which is accompanied by the growth of the current fluctuation. This indicates that nonequilibrium underdamped MCT is not equivalent to the corresponding overdamped MCT, even at long time-scales after the early stage of the beta relaxation. It is verified that the effect of correlations to the density-current modes is, however, negligible in sheared thermostated underdamped systems.

cond-mat.stat-mech↗

arXiv2013

Mode coupling theory for sheared granular liquids

Sheared granular liquids are studied by the mode coupling theory. It is shown that, in contrast to thermostatted systems, current correlations play an essential role in the dynamics. The theory predicts that the plateau of the density time-correlator disappears for most situations, while it appears in the elastic limit. The result is compatible with molecular dynamics simulations.

cond-mat.stat-mech↗

arXiv2012

Nonequilibrium mode-coupling theory for uniformly sheared underdamped systems

Nonequilibrium mode-coupling theory (MCT) for uniformly sheared underdamped systems is developed, starting from the microscopic thermostatted SLLOD equation, and the corresponding Liouville equation. Special attention is paid to the translational invariance in the sheared frame, which requires an appropriate definition of the transient time-correlators. The derived MCT equation satisfies the alignment of the wavevectors, and is manifestly translationally invariant. Isothermal condition is implemented by the introduction of the current fluctuation in the dissipative coupling to the thermostat. This current fluctation grows in the $α$-relaxation regime, which generates a deviation of the yield stress in the glassy phase from the overdamped case. Response to a perturbation of the shear rate demonstrates an inertia effect which is not observed in the overdamped case. Our theory turns out to be a non-trivial extension of the theory by Fuchs and Cates (J. Rheol. 53(4), 2009) to underdamped systems. Since our starting point is identical to that by Chong and Kim (Phys. Rev. E 79, 2009), the contradictions between Fuchs-Cates and Chong-Kim are resolved.

cond-mat.stat-mech↗

arXiv2012

Geometrical Pumping in Quantum Transport: Quantum Master Equation Approach

For an open quantum system, we investigate the pumped current induced by a slow modulation of control parameters on the basis of the quantum master equation and full counting statistics. We find that the average and the cumulant generating function of the pumped quantity are characterized by the geometrical Berry-phase-like quantities in the parameter space, which is associated with the generator of the master equation. From our formulation, we can discuss the geometrical pumping under the control of the chemical potentials and temperatures of reservoirs. We demonstrate the formulation by spinless electrons in coupled quantum dots. We show that the geometrical pumping is prohibited for the case of non-interacting electrons if we modulate only temperatures and chemical potentials of reservoirs, while the geometrical pumping occurs in the presence of an interaction between electrons.

cond-mat.mes-hall↗