arXiv subjects

Shinji Iida

Publications and source records attributed to Shinji Iida.

5 recordsLinked to original sources

arXiv2021

Second moments of work and heat for a single particle stochastic heat engine in a breathing harmonic potential

We consider a simple model of a stochastic heat engine, which consists of a single Brownian particle moving in a one-dimensional periodically breathing harmonic potential. Overdamped limit is assumed. Expressions of second moments (variances and covariances ) of heat and work are obtained in the form of integrals, whose integrands contain functions satisfying certain differential equations. The results in the quasi-static limit are simple functions of temperatures of hot and cold thermal baths. The coefficient of variation of the work is suggested to give an approximate probability for the work to exceeds a certain threshold. During derivation, we get the expression of the cumulant-generating function.

cond-mat.stat-mech↗

arXiv2019

WKB and "Cubic-WKB" methods as an adiabatic approximation

This paper shows that WKB wave function can be expressed in the form of an adiabatic expansion. To build a bridge between two widely invoked approximation schemes seems pedagogically instructive. Further "cubic-WKB" method that has been devised in order to overcome the divergence problem of WKB can be also presented in the form of an adiabatic approximation: The adiabatic expansion of a wave function contains a certain parameter. When this parameter is adjusted so as to make the next order correction vanish approximately, the adiabatic wave function becomes equivalent to that of the "cubic-WKB".

quant-ph↗

arXiv2006

A new stochastic cellular automaton model on traffic flow and its jamming phase transition

A general stochastic traffic cellular automaton (CA) model, which includes slow-to-start effect and driver's perspective, is proposed in this paper. It is shown that this model includes well known traffic CA models such as Nagel-Schreckenberg model, Quick-Start model, and Slow-to-Start model as specific cases. Fundamental diagrams of this new model clearly show metastable states around the critical density even when stochastic effect is present. We also obtain analytic expressions of the phase transition curve in phase diagrams by using approximate flow-density relations at boundaries. These phase transition curves are in excellent agreement with numerical results.

cond-mat.stat-mech↗

arXiv2003

Energy level statistics in weakly disordered systems: from quantum to diffusive regime

We calculate two-point energy level correlation function in weakly disorderd metallic grain with taking account of localization corrections to the universal random matrix result. Using supersymmetric nonlinear sigma model and exactly integrating out spatially homogeneous modes, we derive the expression valid for arbitrary energy differences from quantum to diffusive regime for the system with broken time reversal symmetry. Our result coincides with the one obtained by Andreev and Altshuler [Phys. Rev. Lett. 72, 902 (1995)] where homogeneous modes are perturbatively treated.

cond-mat.dis-nn↗

arXiv2001

Energy-level correlations in chiral symmetric disordered systems: Corrections to the universal results

We investigate the deviation of the level-correlation functions from the universal form for the chiral symmetric classes. Using the supersymmetric nonlinear sigma model we formulate the perturbation theory. The large energy behavior is compared with the result of the diagrammatic perturbation theory. We have the diffuson and cooperon contributions even in the average density of states. For the unitary and orthogonal classes we get the small energy behavior that suggests a weakening of the level repulsion. For the symplectic case we get a result with opposite tendency.

cond-mat.dis-nn↗