arXiv subjects

S. V. Poltavtsev

Publications and source records attributed to S. V. Poltavtsev.

25 records · Page 2Linked to original sources

arXiv2014

Noise spectroscopy of the optical microcavity: nonlinear amplification of the spin noise signal and giant noise

The spin-fluctuations-related Kerr rotation noise of the optical beam reflected from a microcavity with a quantum well in the intermirror gap is studied. In the regime of anti-crossing of the cavity polariton branches, the several hundred times enhancement of the noise signal, or giant noise, is observed. The effect of the amplification of the noise signal is explained by the nonlinear instability of the microcavity. In the frame of the developed model of built-in amplifier, the non-trivial properties of the noise signal in the regime of the negative detuning of microcavity are described.

cond-mat.mes-hall↗

arXiv2014

Optics of spin-noise-induced gyrotropy of asymmetric microcavity

The optical gyrotropy noise of a high-finesse semiconductor Bragg microcavity with an embedded quantum well (QW) is studied at different detunings of the photon mode and the QW exciton resonances. A strong suppression of the noise magnitude for the photon mode frequencies lying above exciton resonances is found. We show that such a critical behavior of the observed optical noise power is specific of asymmetric Fabry-Perot resonators. As follows from our analysis, at a certain level of intracavity loss, the reflectivity of the asymmetric resonator vanishes, while the polarimetric sensitivity to the gyrotropy changes dramatically when moving across the critical point. The results of model calculations are in a good agreement with our experimental data on the spin noise in a single-quantum-well microcavity and are confirmed also by the spectra of the photo-induced Kerr rotation in the pump-probe experiments.

cond-mat.mes-hall↗

arXiv2014

Spin noise spectroscopy of a single-quantum-well microcavity

We report on the first experimental observation of spin noise in a single semiconductor quantum well embedded into a microcavity. The great cavity-enhanced sensitivity to fluctuations of optical anisotropy has allowed us to measure the Kerr rotation and ellipticity noise spectra in the strong coupling regime. The spin noise spectra clearly show two resonant features: a conventional magneto-resonant component shifting towards higher frequencies with magnetic field and an unusual "nonmagnetic" component centered at zero frequency and getting suppressed with increasing magnetic field. We attribute the first of them to the Larmor precession of free electron spins, while the second one being presumably due to hyperfine electron-nuclei spin interactions.

cond-mat.mes-hall↗

arXiv2014

Photon echoes retrieved from semiconductor spins: access to basis for long-term optical memories

The possibility to store optical information is important for classical and quantum communication. Atoms or ions as well as color centers in crystals offer suitable two-level systems for absorbing incoming photons. To obtain a reliable transfer of coherence, strong enough light-matter interaction is required, which may enforce use of ensembles of absorbers, but has the disadvantage of unavoidable inhomogeneities leading to fast dephasing. This obstacle can be overcome by echo techniques that allow recovery of the information as long as the coherence is preserved. Albeit semiconductor quantum structures appear appealing for information storage due to the large oscillator strength of optical transitions, inhomogeneity typically is even more pronounced for them and most importantly the optical coherence is limited to nanoseconds or shorter. Here we show that by transferring the information to electron spins the storage times for the optical coherence can be extended by orders of magnitude up to the spin relaxation time. From the spin reservoir it can be retrieved on purpose by inducing a stimulated photon echo. We demonstrate this for an n-doped CdTe/(Cd,Mg)Te quantum well for which the storage time thereby could be increased by more than three orders of magnitude from the picosecond-range up to tens of nanoseconds.

cond-mat.mes-hall↗

arXiv2013

Optically Controlled Excitonic Transistor

Optical control of exciton fluxes is realized for indirect excitons in a crossed-ramp excitonic device. The device demonstrates experimental proof of principle for all-optical excitonic transistors with a high ratio between the excitonic signal at the optical drain and the excitonic signal due to the optical gate. The device also demonstrates experimental proof of principle for all-optical excitonic routers.

cond-mat.mes-hall↗

arXiv2012

Magnetic field control of photon echo in the electron-trion system: Shuffling of coherences between optically accessible and inaccessible states

We report on magnetic field induced oscillations of the photon echo signal from negatively charged excitons in a CdTe/(Cd,Mg)Te semiconductor quantum well. The oscillatory signal is due to Larmor precession of the electron spin about a transverse magnetic field and depends sensitively on the polarization configuration of the exciting and refocusing pulses. The echo amplitude can be fully tuned from maximum down to zero depending on the time delay between the two pulses and the magnetic field strength. The results are explained in terms of the optical Bloch equations accounting for the spin level structure of electron and trion.

cond-mat.mes-hall↗

arXiv2008

Effect of annealing on the hyperfine interaction in InAs/GaAs quantum dots

The hyperfine interaction of an electron with nuclei in the annealed self-assembled InAs/GaAs quantum dots is theoretically analyzed. For this purpose, the annealing process, and energy structure of the quantum dots are numerically modeled. The modeling is verified by comparison of the calculated optical transitions and of the experimental data on photoluminescence for set of the annealed quantum dots. The localization volume of the electron in the ground state and the partial contributions of In, Ga, and As nuclei to the hyperfine interaction are calculated as functions of the annealing temperature. It is established that the contribution of indium nuclei into the hyperfine interaction becomes predominant up to high annealing temperatures (T = 980 C) when the In content in the quantum dots does not exceed 25%. Effect of the nuclear spin fluctuations on the electron spin polarization is numerically modeled. Effective field of the fluctuations is found to be in good agreement with experimental data available.

cond-mat.other↗