arXiv subjects

K. Dini

Publications and source records attributed to K. Dini.

8 recordsLinked to original sources

arXiv2026

A Photonic Tautochrone

We propose to implement an optical analogue of the tautochrone property of the cycloid to allow the focusing of ultrashort pulses inside photonic systems. This allows to enhance nonlinear effects, resulting in orders of magnitude increase of nonlinearity-induced phase shifts, while employing low irradiances. Building upon the optical-mechanical analogy, we show how to produce optical limiters for temporal light pulses, and how to implement temporal bistability and even multistability with large numbers of states. Finally, we move this concept to the quantum realm and predict a tautochrone quantum blockade regime with a stronger antibunching.

physics.optics↗

arXiv2019

On the possibility of a terahertz light emitting diode based on a dressed quantum well

We consider theoretically the realization of a tunable terahertz light emitting diode from a quantum well with dressed electrons placed in a highly doped p-n junction. In the considered system the strong resonant dressing field forms dynamic Stark gaps in the valence and conduction bands and the electric field inside the p-n junction makes the QW asymmetric. It is shown that the electrons transiting through the light induced Stark gaps in the conduction band emit photons with energy directly proportional to the dressing field. This scheme is tunable, compact, and shows a fair efficiency.

cond-mat.mes-hall↗

arXiv2018

All-to-all connected networks by multi-frequency excitation of polaritons

We analyze theoretically a network of all-to-all coupled polariton modes, realized by a trapped polariton condensate excited by a comb of different frequencies. In the low-density regime the system dynamically finds a state with maximal gain defined by the average intensities (weights) of the excitation beams, analogous to active mode locking in lasers, and thus solves a maximum eigenvalue problem set by the matrix of weights. The method opens the possibility to tailor a superposition of populated bosonic modes in the trapped condensate by appropriate choice of drive.

cond-mat.mes-hall↗

arXiv2017

Optically induced Lifshitz transition in bilayer graphene

It is shown theoretically that the renormalization of the electron energy spectrum of bilayer graphene with a strong high-frequency electromagnetic field (dressing field) results in the Lifshitz transition - the abrupt change in the topology of the Fermi surface near the band edge. This effect substantially depends on the polarization of the field: The linearly polarized dressing field induces the Lifshitz transition from the quadruply-connected Fermi surface to the doubly-connected one, whereas the circularly polarized field induces the multicritical point, where the four different Fermi topologies may coexist. As a consequence, the discussed phenomenon creates physical basis to control the electronic properties of bilayer graphene with light.

cond-mat.mes-hall↗

arXiv2016

All-optical band engineering of gapped Dirac materials

We demonstrate theoretically that the interaction of electrons in gapped Dirac materials (gapped graphene and transition-metal dichalchogenide monolayers) with a strong off-resonant electromagnetic field (dressing field) substantially renormalizes the band gaps and the spin-orbit splitting. Moreover, the renormalized electronic parameters drastically depend on the field polarization. Namely, a linearly polarized dressing field always decreases the band gap (and, particularly, can turn the gap into zero), whereas a circularly polarized field breaks the equivalence of valleys in different points of the Brillouin zone and can both increase and decrease corresponding band gaps. As a consequence, the dressing field can serve as an effective tool to control spin and valley properties of the materials and be potentially exploited in optoelectronic applications.

cond-mat.mes-hall↗

arXiv2016

Magnetic properties of a two-dimensional electron gas strongly coupled to light

Considering the quantum dynamics of 2DEG exposed to both a stationary magnetic field and an intense high-frequency electromagnetic wave, we found that the wave decreases the scattering-induced broadening of Landau levels. Therefore, various magnetoelectronic properties of two-dimensional nanostructures (density of electronic states at Landau levels, magnetotransport, etc) are sensitive to the irradiation by light. Thus, the elaborated theory paves a way to optical controlling magnetic properties of 2DEG.

cond-mat.mes-hall↗

arXiv2015

Magnetoelectronic properties of graphene dressed by a high-frequency field

We solved the Schr\"odinger problem for electrons in graphene subjected to both a stationary magnetic field and a strong high-frequency electromagnetic wave (dressing field). The found solutions of the problem are used to describe the magnetoelectronic properties of dressed graphene. It follows from the present analysis that both optical characteristics and electronic transport are very sensitive to the dressing field. Particularly, the field strongly changes the spectra of optical absorption and the Shubnikov-de Haas oscillations. As a result, the developed theory opens a way for controlling magnetoelectronic properties of graphene with light.

cond-mat.mes-hall↗

arXiv2013

Hybrid Boltzmann Gross-Pitaevskii Theory of Bose-Einstein Condensation and Superfluidity in Open Driven-Dissipative Systems

We derive a theoretical model which describes Bose-Einstein condensation in an open driven-dissipative system. It includes external pumping of a thermal reservoir, finite life time of the condensed particles and energy relaxation. The coupling between the reservoir and the condensate is described with semi-classical Boltzmann rates. This results in a dissipative term in the Gross-Pitaevskii equation for the condensate, which is proportional to the energy of the elementary excitations of the system. We analyse the main properties of a condensate described by this hybrid Boltzmann Gross-Pitaevskii model, namely, dispersion of the elementary excitations, bogolon distribution function, first order coherence, dynamic and energetic stability, drag force created by a disorder potential. We find that the dispersion of the elementary excitations of a condensed state fulfils the Landau criterion of superfluidity. The condensate is dynamically and energetically stable as longs it moves at a velocity smaller than the speed of excitations. First order spatial coherence of the condensate is found to decay exponentially in 1D and with a power law in 2D, similarly with the case of conservative systems. The coherence lengths are found to be longer due to the finite life time of the condensate excitations. We compare these properties with the ones of a condensate described by the popular "diffusive" models in which the dissipative term is proportional to the local condensate density. In the latter, the dispersion of excitations is diffusive which as soon as the condensate is put into motion implies finite mechanical friction and can lead to an energetic instability.

cond-mat.quant-gas↗