Electron-phonon interaction is a major source of optical dephasing in semiconductor quantum dots. Within density matrix theory the electron-phonon considered up to second order correlation expansion, allowing calculation kinetic dynamics optically induced nonlinearities GaAs dots for arbitrary pulse strengths and shapes. We find Rabi oscillations renormalized damping that depends on input strength, behavior not known from exponential mechanisms.

We use time-resolved x-ray absorption spectroscopy to investigate the unoccupied electronic density of states warm dense copper that is produced isochorically through an ultrafast optical pulse. The temperature superheated electron-hole plasma, which ranges from 4000 10 000 K, was determined by comparing measured spectrum with a simulation. structure adequately described high state calculated functional theory. dynamics electron consistent two-temperature model, while temperature-dependent...

The adsorption of molecules to the surface carbon nanostructures opens a new field hybrid systems with distinct and controllable properties. We present microscopic study optical absorption in nanotubes functionalized molecular spiropyran photoswitches. switching process induces change dipole moment leading significant coupling charge carriers nanotube. As result, spectra tubes reveal considerable redshift transition energies depending on state molecule. Our results suggest that are excellent...

Ultrafast experiments using sub-picosecond pulses of light are poised to play an important role in the study and use topological materials and, particularly, three-dimensional Dirac Weyl semimetals. Many these materials’ characteristic properties—their linear band dispersion, Berry curvature, near-vanishing density states at Fermi energy, sensitivity crystalline time-reversal symmetries—are closely related their sub- few-picosecond response light. measurements offer opportunity explore...

We describe measurements of spin dynamics in the two-dimensional electron gas GaAs/GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe relaxation rates polarization waves wavevector range from zero $6\times 10^4$ cm$^{-1}$. find that lifetime is maximal at nonzero wavevector, contrast with expectation based on ordinary diffusion, but quantitative agreement recent theories treat diffusion presence spin-orbit coupling.

We combine the results of terahertz time-domain spectroscopy with far-infrared transmission and reflectivity to obtain conductivity SrRuO3 over an unprecedented continuous range in frequency, allowing us characterize approach zero frequency as a function temperature. show that follows simple phenomenological form, analytic structure fundamentally different from predicted by standard theory metals.

Abstract Ninety-two individuals of Sitobion avenae (F.) collected throughout Britain in 1979 and 1980, were cloned investigated genetically by electrophoresis 14 enzymes representing 26 loci. Percentage polymorphism (P) differed considerably between years, 64% (16/25 loci) 19% (5/26) whereas average heterozygosity ( ) was low ca . 2%) both years confined mainly to one locus, EST-1. The prevalence homozygous allozyme variation supports ecological findings suggesting S. be largely anholocyclic...

The impact of coherence on the nonlinear optical response and stationary transport is studied in quantum cascade laser structures. Nonequilibrium effects such as pump-probe signals, spatiotemporally resolved electron density evolution, subband population dynamics (Rabi flopping) well current characteristics are investigated within a microscopic density-matrix approach. Focusing recently observed gain oscillations, it found that inclusion leads to observable coherent opposite parameter...

Strong radial confinement in semiconductor nanowires leads to modified electronic and phononic energy spectra. We analyze the current response interplay between quantum effects of electron phonon systems a gate-defined double dot nanowire. show that spectroscopy inelastic transitions two dots can be used as an experimental probe confined environment. The resulting discrete peak structure measurements is explained by theoretical modeling mode spectrum, where piezoelectric coupling crucial importance.

We report ultrafast transient-grating measurements of crystals the three-dimensional Dirac semimetal cadmium arsenide, Cd3As2, at both room temperature and 80 K. After photoexcitation with 1.5-eV photons, charge-carriers relax by two processes, one duration 500 fs other 3.1 ps. By measuring complex phase change in reflectance, we determine that faster signal corresponds to a decrease absorption, slower light's velocity, probe energy. attribute these signals electrons' filling space, first...

We review the different aspects of interaction mesoscopic quantum systems with gravitational fields. first discuss briefly foundations general relativity and mechanics. Then, we consider non-relativistic expansions Klein-Gordon Dirac equations in post-Newtonian approximation. After a short overview classical waves, two proposed mechanisms: (i) use fluids as generator and/or detector waves laboratory, (ii) inclusion gravitomagnetic fields study properties rotating superconductors. The...

Recent years have seen the rapid discovery of solids whose low-energy electrons a massless, linear dispersion, such as Weyl, line-node, and Dirac semimetals. The remarkable optical properties predicted in these materials show their versatile potential for optoelectronic uses. However, little is known response picoseconds after absorbing photon. Here, we measure ultrafast dynamics four that share non-trivial band structure topology but differ chemically, structurally, structures: ZrSiS, which...

We demonstrate an intrinsically fast Seebeck-type metal–semimetal–metal infrared photodetector based on Cd3As2 crystals. The Seebeck voltage is induced under off-center illumination, leading to asymmetric temperature gradients and a net current flow. room-temperature responsivity of the sensor 0.27 mA/W. photocurrent signal readily registered at modulation frequency 6 kHz, intrinsic bandwidth predicted approach terahertz range. depends optical power frequency. Our study demonstrates that...

An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on gold photocathode at angle of 20° and photoemitted electrons focused by large aperture magnetic solenoid lens. The high quantum efficiency, 600 fs temporal resolution, 6 mm imaging length in the spectral direction. Its single shot capability eliminates smearing due to sweep jitter, allows recording dynamics samples that undergo nonreversible changes.

Infrared spectroscopy is used to investigate the electronic structure and charge carrier relaxation in crystalline films of ${\mathrm{CrO}}_{2}$ which simplest all half-metallic ferromagnets. Chromium dioxide a bad metal at room temperature but it has remarkably low residual resistivity $(<5 \ensuremath{\mu}\ensuremath{\Omega}\mathrm{cm})$ despite small spectral weight associated with free absorption. The infrared measurements show that due collapse scattering rate $\ensuremath{\omega}<2000...

The ultrafast optical response of nodal-line semimetals ZrSiS and ZrSiSe was studied in the near-infrared using transient reflectivity. materials exhibit similar responses, characterized by two features, well-resolved time energy; first decays after hundreds femtoseconds, second lasts for nanoseconds. Using Drude-Lorentz fits materials' equilibrium reflectance, we show that these are well-represented a sudden change electronic properties (increase screening or reduction plasma frequency)...

Using density matrix theory, the linear and ultrafast nonlinear optical properties of a recently developed terahertz quantum cascade laser are investigated. All relevant excitation regimes, from coherent Rabi flopping up to scattering dominated stationary response, covered by theory. It is shown that coherence transfer between different periods important describe effects.

${\mathrm{SrMnSb}}_{2}$ is a candidate Dirac semimetal whose electrons near the $Y$ point have linear dispersion and low mass of cone. Here we demonstrate that ultrafast, 800-nm optical pulses can launch coherent phonon oscillations in ${\mathrm{Sr}}_{0.94}{\mathrm{Mn}}_{0.92}{\mathrm{Sb}}_{2}$, particularly an ${A}_{g}$ mode at 4.4 THz. Through first-principles calculations electronic phononic structure ${\mathrm{SrMnSb}}_{2}$, show high-amplitude this would displace atoms way transiently...

The occurrence of non-Lorentzian lineshapes is analyzed for a variety nanooptical semiconductor systems such as quantum wells and dots. Their origin traced back to light–matter interaction (light propagation) many-particle correlations (electron–electron electron–phonon interaction).

We report ultrafast optical measurements of the Dirac line-node semimetal ZrSiS and Weyl NbAs, using mid-infrared pump photons from 86 meV to 500 directly excite fermions within linearly dispersing bands. In photoexcited initially form a non-thermal distribution, signified by brief spike in differential reflectivity whose sign is controlled relative energy probe photons. ZrSiS, electron-electron scattering rapidly thermalizes electrons, not observed. Subsequently, hot carriers both materials...

We study the influence of environment on an optically induced rotation a single electron spin in charged semiconductor quantum dot. analyze decoherence mechanisms resulting from dynamical lattice response to charge evolution trion-based optical control scheme. Moreover, we effect finite trion lifetime and imperfections unitary such as off-resonant excitations nonadiabaticity driving. calculate total error operation spin-based qubit $\mathrm{In}\mathrm{As}∕\mathrm{Ga}\mathrm{As}$ dot system...

Abstract We review the different aspects of interaction mesoscopic quantum systems with gravitational fields. first discuss briefly foundations general relativity and mechanics. Then, we consider non‐relativistic expansions Klein‐Gordon Dirac equations in post‐Newtonian approximation. After a short overview classical waves, two proposed mechanisms: (i) use fluids as generator and/or detector waves laboratory, (ii) inclusion gravitomagnetic fields study properties rotating superconductors....

The transfer of heat between electrons and phonons plays a key role for thermal management in future nanowire-based devices, but only few experimental measurements electron-phonon (e-ph) coupling nanowires are available. Here, we combine temperature on an InAs/InP heterostructure nanowire system with finite element modeling to extract information flow mediated by e-ph coupling. We find that the electron phonon temperatures our highly coupled even at as low 2 K. Additionally, evidence usual...