Excitonic Rabi Oscillations Research Articles

Final-state readout of exciton qubits by observing resonantly excited photoluminescence in quantum dots

The authors report on an approach to detect excitonic qubits in semiconductor quantum dots by observing spontaneous emissions from the relevant qubit level. The ground state of excitons is resonantly excited by picosecond optical pulses. Emissions from the same state are temporally resolved with picosecond time resolution. To capture weak emissions, the authors greatly suppress the elastic scattering of excitation beams, by applying obliquely incident geometry to the microphotoluminescence setup. Rabi oscillations of the ground-state excitons appear to be involved in the dependence of emission intensity on excitation amplitude.

Rabi oscillations a quantum dot exposed to quantum light

The influence of the local field on the excitonic Rabi oscillations in an isolated quantum dot driven by the coherent state of light has been theoretically investigated. Local field is predicted to entail the appearance of two oscillatory regimes in the Rabi effect separated by the bifurcation. In the first regime Rabi oscillations are periodic and do not reveal collapse–revivals phenomenon, while in the second one collapse and revivals appear, showing significant difference as compared to those predicted by the standard Jaynes-Cummings model.

Pulse Area Control of Exciton Rabi Oscillation in InAs/GaAs Single Quantum Dot

We investigated the optical properties of an exciton and a charged exciton in an InAs/GaAs single quantum dot (QD) with truncated pyramidal shape by microspectroscopy, and clarified the difference of sub-band structure between the exciton and the charged exciton in the same single QD. We observed the exciton population of the excited states by monitoring the luminescence of the ground state exciton and succeeded in the experimental demonstration of Rabi oscillation of the exciton and the charged exciton. The transition dipole moments estimated from experimental results in a pure InAs QD are 32 and 40 D for the charged exciton and exciton, respectively, which were comparable to those in InGaAs QD.

Local field effects in excitonic population transfer in a driven quantum dot system

We study theoretically the influence of local fields in the excitonic population dynamics of a quantum dot system under the interaction with either CW or pulsed and appropriately chirped electromagnetic fields. Using a microscopic approach for the analysis of the system we present analytical and numerical results from the solution of the optical Bloch equations, with emphasis given to the effects of local fields in excitonic Rabi oscillations and to the conditions that could give rise to population inversion in the system.

Local field effect on Rabi oscillations of excitons localized to quantum islands in a single quantum well

Nonlinear optical response and optical coherence time of excitons localized to quantum islands in a $\mathrm{Ga}\mathrm{As}∕\mathrm{Al}\mathrm{Ga}\mathrm{As}$ single quantum well are studied by the three-pulse photon echo technique. At low temperature, the optical coherence time is estimated to be $1.8\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ from the decay of the photon echo signal. The decay profile for short time delay shows the strong dependence on the input pulse area of the third pulse. Rabi oscillations are also observed. The oscillations show nonlinear behavior affected by the pre-excited polarization. Such behavior can be qualitatively explained by the local field effect due to the exciton-exciton interaction between the localized excitons.

Excitonic dynamics in a single quantum dot within a microcavity

The excitonic dynamics in a single quantum dot within a microcavity is investigated theoretically in terms of the perturbation treatment based on a unitary transformation. The excitonic Rabi oscillations with a damping rate are obtained explicitly. It is shown that the damping rate depends on exciton-phonon coupling constant and the vacuum Rabi frequency. Even at absolute zero temperature and in the vacuum cavity, the exciton-phonon interaction and exciton-photon interaction still cause excitonic decoherence. We also predict that under strong control fields the collapse and revival of excitonic Rabi oscillation may be observed for the quantum dots with small exciton-phonon coupling in the $T\ensuremath{\rightarrow}0$ limit.

Strong light‐matter coupling in a quantum dot: local field effects

Manifestation of local fields in excitonic Rabi oscillations in an isolated arbitrary shaped quantum dot (QD) has been theoretically investigated. Interaction of QD with harmonic electromagnetic field as well as with ultrashort optical pulse has been considered. Bifurcation and anharmonism in the Rabi oscillations in a QD are predicted. Step-like transitions of the inversion as a function of peak pulse strength are demonstrated to be observable in a QD exposed to a Gaussian pulse. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Excitonic Rabi oscillations in a quantum dot: local field impact

The influence of local fields on the excitonic Rabi oscillations in an isolated, arbitrary shaped quantum dot (QD) has been theoretically investigated. QD interaction with both a classical electromagnetic field and quantum light has been considered. In the classical light, time harmonic and ultrashort pulse excitations are analyzed. The general formalism has been formulated for quantum light and applied to the case of a Fock qubit. Noticeable modification of the Rabi oscillation dynamics induced by the local fields is predicted to be observable in QDs exposed to both classical and quantum light. In particular, the bifurcation and anharmonism in the Rabi oscillations have been revealed under time harmonic excitation and a dependence of the Rabi oscillation period on the QD depolarization has been obtained.

Rabi oscillations in a semiconductor quantum dot: Influence of local fields

The influence of electron-hole dipole-dipole interactions (local fields) on the excitonic Rabi oscillations in an isolated quantum dot (QD) has been theoretically investigated. An analysis for the QD interaction with monochromatic field and ultrashort Gaussian pulse has been performed. On the basis of optical Bloch equations the Rabi oscillation dynamics has been investigated. As a result, the bifurcation and essentially anharmonic regimes in the Rabi oscillations in a QD exposed to the monochromatic field have been predicted. The strong dependence of the period of Rabi oscillations on the QD depolarization has been revealed. For the Gaussian pulse it has been shown that the final state of inversion as a function of the pulse peak strength demonstrates step-like transitions.

Rabi Oscillation of Exciton Dressed by Phonons In a QuantumDot

The effect of strong exciton-phonon interaction on the excitonic Rabioscillations in a coherently driven quantum dot in a high-Q single modecavity is investigated theoretically. We show that the Rabi oscillationof exciton dressed by phonons can persists with the Rabi frequencyge-λ/2 at absolute zero temperature, where g is thesingle-photon Rabi frequency and λ is the Huang-Rhys factor. Theresults also present that such coherent oscillations can be modified bymanipulating the Rabi frequency of the driving field.

Exciton Rabi Oscillation in Single Isolated Quantum Dots

The Rabi population oscillation of a single excitonic two-level system in an isolated In x Ga 1-x As quantum dot was examined by quantum wave function interferometry in the time domain. The corresponding energy splitting was also confirmed in an energy-domain measurement. Two-pulse dipole interference on an excited excitonic state revealed a long-lived coherence of zero-dimensional excitonic states and demonstrated coherent population flopping under a strong optical field.

Rabi oscillations of excitons in single quantum dots.

Transient nonlinear optical spectroscopy, performed on excitons confined to single GaAs quantum dots, shows oscillations that are analogous to Rabi oscillations in two-level atomic systems. This demonstration corresponds to a one-qubit rotation in a single quantum dot which is important for proposals using quantum dot excitons for quantum computing. The dipole moment inferred from the data is consistent with that directly obtained from linear absorption studies. The measurement extends the artificial atom model of quantum dot excitonic transitions into the strong-field limit, and makes possible full coherent optical control of the quantum state of single excitons using optical pi pulses.

Excitonic Bloch equations for a two-dimensional system of interacting excitons

We derive the effective Bose Hamiltonian for a system of interacting excitons applying the Usui transformation. The fermionic nonlinearities are consistently included, leading to a density dependent correction to the kinetic Hamiltonian and to a saturation of the exciton oscillator strength. The exciton-exciton interaction potentials due to the Coulomb interaction are calculated, accounting for the spin dependence. Starting from the effective Hamiltonian, we obtain the excitonic Bloch equations. As a first application, we study the problem of excitonic Rabi oscillations in quantum wells.

Three-band excitonic Rabi oscillations in semiconductor quantum wells

Optical Rabi oscillations in atomic two-level systems and excitonic Rabi oscillations in two-band semiconductors are already well established. In contrast to two-level (or two-band) Rabi oscillations, three-level (or three-band) Rabi oscillations offer a rich variety of oscillation dynamics involving both radiative and nonradiative (Raman) transitions. We analyze excitonic three-band Rabi oscillations in semiconductor quantum wells and study, in particular, the role of band-coupling effects and Coulomb effects.

Excitonic Rabi Oscillations in Semiconductors

Excitonic Rabi Oscillations in Semiconductors

Excitonic Rabi Oscillations in Semiconductors

Excitonic Rabi Oscillations in Semiconductors

Dressed semiconductor bloch equations: coherence versus Coulomb scattering in resonantly excited quantum wells

We investigate the role of Coulomb correlation in an electron–hole gas that is strongly driven by an optical pump. Coulomb scattering is treated including Born diagrams and the light-dressing of the carriers is consistently included. When the pump is spectrally tuned at the excitonic resonance, the Born correlation is found to weakly affect the fully coherent Hartree–Fock results. Our model calculations fully support recent and quite unexpected observations of excitonic Rabi oscillations in III–V quantum wells.

Direct Observation of Excitonic Rabi Oscillations in Semiconductors

We observe multiple excitonic optical Rabi oscillations in a semiconductor quantum well. Up to eight oscillation periods of the heavy-hole exciton density on a subpicosecond time scale are observed. An approximate linear dependence of the oscillation frequency on the light field amplitude is established. The experiment is based on a two-color detection scheme which allows for the observation of the heavy-hole exciton density via transmission changes at the light-hole exciton. The observations are in good agreement with theoretical computations based on multiband semiconductor Bloch equations.