arXiv subjects

Mohammadreza Eidi

Publications and source records attributed to Mohammadreza Eidi.

3 recordsLinked to original sources

arXiv2021

Photoinduced Nonperturbative Valley Polarization in Graphene

We investigate a valleytronic device based on graphene with charge separation at different sublattices and correspondingly at nonequivalent valleys. We characterize the maximality condition of valley polarization and investigate the parameters and conditions upon which we can coherently control the carriers and store data via valley degree of freedom. The valley polarization is controlled by the amplitude as well as the carrier envelope phase of the pulse and the curvature of the electron trajectory in the reciprocal space. When strong field excitation is taken into account, the optical selection rule in perturbative optics is replaced by the nonadiabatic geometric effects. As a result, a nonperturbative valley polarization in two dimensional Dirac materials is induced regardless of having an intrinsic bandgap. Microscopically, such a nonreciprocal response of graphene in the chiral electric field is encoded by the quantum Berry phase, as a (pseudo) magnetoelectric monopole.

cond-mat.mes-hall↗

arXiv2019

Static coherent states method for investigating high-order harmonic generation in single-electron molecular systems

In this report, a novel methodology based on the static coherent states approach is introduced with the capability of calculating various strong-field laser-induced nonlinearities in full dimensional single-electron molecular systems; an emphasis is made on the high-order harmonic generation. To evaluate the functionality of this approach, we present a case study of the Hydrogen molecular ion \ih interacting with a few-cycle linearly polarized optical laser with trapezoidal waveform. We detected that the accuracy of the obtained harmonics is considerably enhanced by averaging the expectation value of the acceleration of the single electron over a set of identical random simulations. Subsequently, the presented approach demands a significantly lower number of basis sets than the regular exact three dimensional unitary split-operator solvers of time dependent Schr{ö}dinger equation that necessitate an extremely large number of data points in the coordinate space, and so the computational cost. Additionally, applying static coherent states method, we have investigated isolated attosecond pulse generation using the polarization gating technique, which combines two delayed counter rotating circular laser pulses, and opens up a gate at the central portion of the superposed pulse.

quant-ph↗

arXiv2016

A new version of fermion coupled coherent states method: Theory and applications in simulation of two-electron systems

We report a new version of fermion coupled coherent states method (FCCS-II) to simulate two-electron systems based on a self-symmetrized six-dimensional (6D) coherent states grid. Unlike the older fermion coupled coherent states method (FCCS-I), FCCS-II does not need any new equations in comparison with the coupled coherent states method. FCCS-II uses a simpler and more efficient approach for symmetrizing the spatial wave function in the simulation of fermionic systems. This method, has significantly increased the speed of computations and give us the capability to simulate the quantum systems with the larger CS grids. We apply FCCS-II to simulate the Helium atom and the Hydrogen molecule based on grids with a large numbers of coherent states. FCCS-II with a relatively low number of CS gives a potential energy curve for H2 that is very close to the exact potential curve. Moreover, we have re-derived all the important equations of the FCCS-I method.

physics.atom-ph↗