Hirobumi Mineo

We consider evolution with a reservoir in which old versions of viral strains persist. This phenomenon is typical for HIV infection and is in fact one of the main obstacles in treating the infectio...

Controlling the unidirectional rotation of π-electrons is a key challenge in the development of organic electronic and optoelectronic devices. In our recent study [Mineo et al., J. Chem. Phys. 161, 194311 (2024)], we explored the generation of unidirectional π-electron rotations in both low- and high-symmetry molecules by utilizing helical photon-dressed states. These states were formed using circularly or elliptically polarized laser fields within a minimal three-state electronic model under the frozen-nuclei approximation. However, that approach did not address the preparation of appropriate initial conditions or the tailored light–matter interactions required to create photon-dressed states. To overcome this limitation, it is crucial to consider a process that prepares the photon-dressed states from the electronic ground state through optical pumping with pulsed lasers. In this work, we analytically design such pulsed lasers to induce helical photon-dressed states in both low- and high-symmetry aromatic rings, starting from the ground state. We further incorporate the nuclear vibrational effects within the adiabatic approximation and apply those designed laser fields to low-symmetry aromatic rings. Finally, we numerically demonstrate the generation of angular momenta associated with the photon-dressed states using the analytically designed laser fields. Vibrational effects are found to selectively influence the stability of specific photon-dressed states.

We theoretically demonstrated that helical-photon-dressed states determine the rotational directions of the π-electrons of aromatic ring molecules formed by a circularly polarized or an elliptically polarized laser. This theory was verified using a minimal three-electronic-state model under the frozen nuclei condition. The model consists of the ground state and either a doubly degenerate electronic excited state or two quasi-degenerate excited states. Three helical-photon-dressed states were derived by solving the time-dependent Schrödinger equation within the semi-classical treatment of light–molecule interactions and rotating wave approximation. The angular momenta of the two helical-photon-dressed states represent the classical rotational direction, and that of the remaining state represents the opposite rotation, that is, non-classical rotation. Classical rotation means that π-electrons have the same rotational direction as that of a given helical electric field vector and obeys the classical equations of motion. Non-classical rotation indicates that the rotational direction is opposite to that of the helical electric field vector. Non-classical rotation is forbidden in an aromatic ring molecule with high symmetry formed by a circularly polarized laser but is allowed in a low symmetric aromatic ring molecule. The sum of the angular momenta of the three dressed states is zero. This is called the sum law for the angular momentum components in this paper. Benzene (D6h) and toluene (CS) were adopted as typical aromatic ring molecules of high and low symmetries, respectively. Finally, considering the effects of nuclear vibrations in the adiabatic approximation, an expression for the π-electron angular momentum was derived and applied to toluene.

In this paper, we study the phase structure of the product of D * D order matrices. In each round, we randomly choose a matrix from a finite set of d matrices and multiply it with the product from the previous round. Initially, we derived a functional equation for the case of matrices with real eigenvalues and correlated choice of matrices, which led to the identification of several phases. Subsequently, we explored the case of uncorrelated choice of matrices and derived a simpler functional equation, again identifying multiple phases. In our investigation, we observed a phase with a smooth distribution in steady-state and phases with singularities. For the general case of D-dimensional matrices, we derived a formula for the phase transition point. Additionally, we solved a related evolution model. Moreover, we examined the relaxation dynamics of the considered models. In both the smooth phase and the phase with singularities, the relaxation is exponential. The superiority of relaxation in the smooth phase depends on the specific case.

Herein we review a theoretical study of unidirectional π-electron rotation in aromatic ring molecules, which originates from two quasi-degenerate electronic excited states created coherently by a linearly polarized ultraviolet/visible laser with a properly designed photon polarization direction. Analytical expressions for coherent π-electron angular momentum, ring current and ring current-induced magnetic field are derived in the quantum chemical molecular orbital (MO) theory. The time evolution of the angular momentum and the ring current are expressed using the density matrix method under Markov approximation or by solving the time-dependent Schrödinger equation. In this review we present the results of the following quantum control scenarios after a fundamental theoretical description of coherent angular momentum, ring current and magnetic field: first, two-dimensional coherent π-electron dynamics in a non-planar (P)-2,2’-biphenol molecule; second, localization of the coherent π-electron ring current to a designated benzene ring in polycyclic aromatic hydrocarbons; third, unidirectional π-electron rotations in low-symmetry aromatic ring molecules based on the dynamic Stark shift of two relevant excited states that form a degenerate state using the non-resonant ultraviolet lasers. The magnetic fields induced by the coherent π-electron ring currents are also estimated, and the position dependence of the magnetic fluxes is demonstrated.