Excitonic dynamics of a quantum dot coupled to a laser-driven semiconductor microcavity (original) (raw)
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Dynamics of the excitations of a quantum dot in a microcavity
Physical Review B, 2004
We study the dynamics of a quantum dot embedded in a three-dimensional microcavity in the strong coupling regime in which the quantum dot exciton has an energy close to the frequency of a confined cavity mode. Under the continuous pumping of the system, confined electron and hole can recombine either by spontaneous emission through a leaky mode or by stimulated emission of a cavity mode that can escape from the cavity. The numerical integration of a master equation including all these effects gives the dynamics of the density matrix. By using the quantum regression theorem, we compute the first and second order coherence functions required to calculate the photon statistics and the spectrum of the emitted light. Our main result is the determination of a range of parameters in which a state of cavity modes with poissonian or sub-poissonian (non-classical) statistics can be built up within the microcavity. Depending on the relative values of pumping and rate of stimulated emission, either one or two peaks close to the excitation energy of the dot and/or to the natural frequency of the cavity are observed in the emission spectrum. The physics behind these results is discussed.
Coherent excitation of a strongly coupled quantum dot - cavity system
2009
We have studied the coherent excitation of a strongly coupled QD/photonic crystal cavity system. Time-resolved reflectivity measurements show the vacuum Rabi oscillation of the dot in the cavity. Next, we considered the resonant driving of a cavity-detuned dot, which efficiently populates the cavity mode. This cavity-controlled read-out channel allows high-resolution single quantum dot spectroscopy. Autocorrelation measurements on the cavity mode show antibunching and suggest the use of the resonantly driven QD/cavity system as an on-demand source of single photons with potentially near-unity indistinguishability.
Optik, 2019
The recent developments in quantum technology physics have shown tremendous progress in the storage,processing and transfer of quantum information using quantum bits (Qubits) [1-3]. Quantum coherence which is a necessary requirement for realistic quantum communication system is extremely fragile and can be destroyed by interaction with the environment. Semiconductor quantum dots (QDs) embedded in micro-cavity have recently emerged as an attractive candidate for the implementation of quantum computing platforms [4-8]. Instead of the usual two-level real atoms, excitons in the QDs are considered as an alternative two level systems characterized by strong exciton-phonon interactions [9-12]. For practical implementation of quantum information processing based on QDs, it is important to minimize the influence of lattice vibrations which tends to destroy their coherence. Thus it is important to take into account exciton-phonon interactions in the study of quantum-dot cavity system. Experimental observation of vacuum Rabi Oscillations in atomic [13] as well as in solid state systems [14-16] provides evidence for strong coupling regime in micro cavity systems. Thus QDs embedded in semiconductor micro-cavity have emerged as an exciting platform to study cavity QED [17-19]. Recently proposals have been put forward to use nano structured photonic nanocavities made of χ (2) nonlinear materials as prospectives devices for application in quantum information processing, quantum logic gates and all optical switches [20, 21].One of the main aims of working with such systems is to have a scalable integrated quantum photonic technology with the probability to work at telecommunication wavelengths. In this paper, we seek to theoretically study the quantum oscillations in a coherently driven quantum dot-cavity system in the presence of a χ (2) nonlinear substrate and strong exciton-phonon interactions.
Electronic/Optical Coherence in Low Dimensional Semiconductors and Atomic Gases Session II
In recent experiments on coupled quantum dot (QD) optical cavity systems a pronounced interaction between the dot and the cavity has been observed even for detunings of many cavity linewidths. This interaction has been attributed to an incoherent phonon-mediated scattering process and is absent in atomic systems. Here, we demonstrate that despite its incoherent nature, this process preserves the signatures of coherent interaction between a QD and a strong driving laser, which may be observed via the optical emission from the off-resonant cavity. Under bichromatic driving of the QD, the cavity emission exhibits spectral features consistent with optical dressing of the QD transition. In addition to revealing new aspects of the off-resonant QD-cavity interaction, this result provides a new, simpler means of coherently probing QDs than traditional approaches and opens the possibility of employing off-resonant cavities to optically interface QD-nodes in quantum networks.
Detuning effect in quantum dynamics of a strongly coupled single quantum dot–cavity system
Journal of Physics: Condensed Matter, 2008
The quantum dynamics of a strongly coupled single quantum dot-cavity system with non-zero detuning in a phonon bath is investigated theoretically in terms of a perturbation treatment based on a unitary transformation and an operator displacement. The decoherence due to phonons as a function of the detuning between the cavity mode and exciton is obtained analytically. It is shown that the detuning has a significant impact on the quantum dot exciton lifetime. In realistic experimental conditions, the calculated exciton lifetimes are in good agreement with recent experimental observation (Hennessy et al 2007 Nature 445 896).
Controlling the excitation spectrum of a quantum dot array with a photon cavity
Physical Review B
We use a recently proposed quantum electrodynamical density theory functional in a real-time excitation calculation for a two-dimensional electron gas in a square array of quantum dots in an external constant perpendicular magnetic field to model the influence of cavity photons on the excitation spectra of the system. The excitation is generated by a short electrical pulse. The quantum dot array is defined in an AlGaAs-GaAs heterostructure, which is in turn embedded in a parallel plate far-infrared photon microcavity. The required exchange and correlation energy functionals describing the electron-electron and electron-photon interactions have therefore been adapted for a two-dimensional electron gas in a homogeneous external magnetic field. We predict that the energies of the excitation modes activated by the pulse are generally redshifted to lower values in the presence of a cavity. The redshift can be understood in terms of the polarization of the electron charge by the cavity photons and depends on the magnetic flux, the number of electrons in a unit cell of the lattice, and the electron-photon interaction strength. We find an interesting interplay of the exchange forces in a spin-polarized two-dimensional electron gas and the square-lattice structure leading to a small but clear blueshift of the excitation mode spectra when one electron resides in each dot.
Cavity quantum electrodynamics with semiconductor quantum dots
The Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement meeting, 2013
We describe a coherent control technique for coupling electron spin states associated with semiconductor double-dot molecule to a microwave stripline resonator on a chip. We identify a novel regime of operation in which strong interaction between a molecule and a resonator can be achieved with minimal decoherence, reaching the so-called strong coupling regime of cavity QED. We describe potential applications of such a system, including low-noise coherent electrical control, fast QND measurements of spin states, and long-range spin coupling.
Microcavity controlled coupling of excitonic qubits
Nature Communications, 2013
Controlled non-local energy and coherence transfer enables light harvesting in photosynthesis and non-local logical operations in quantum computing. The most relevant mechanism of coherent coupling of distant qubits is coupling via the electromagnetic field. Here, we demonstrate the controlled coherent coupling of spatially separated excitonic qubits via the photon mode of a solid state microresonator. This is revealed by two-dimensional spectroscopy of the sample's coherent response, a sensitive and selective probe of the coherent coupling. The experimental results are quantitatively described by a rigorous theory of the cavity mediated coupling within a cluster of quantum dots excitons. Having demonstrated this mechanism, it can be used in extended coupling channels -sculptured, for instance, in photonic crystal cavities -to enable a long-range, non-local wiring up of individual emitters in solids. arXiv:1206.0592v1 [quant-ph]
Quantum Information Processing, 2021
We systematically study the influence of simultaneously modulating the input laser intensity and quantum dot (QD) resonance frequecy on the mean-field dynamics, fluctuation energy transfer and entanglement in a optomechanical semiconductor resonator embedded with a QD. We show that the modulation and the hybrid system can be engineered to attain the desired mean-field values, control the fluctuation energy transfer and the entanglement between the various degrees of freedom. A remarkably high degree of entanglement can be achieved by modulating only the QD frequency. The interplay between the two modulations leads to an entanglement which lies between that generated solely by modulating either the QD or the pump laser intensity. A transition from low stationary to large dynamical entanglement occurs as we switch on the modulation. This study opens up new possibilities for optimal control strategies and can be used for data signal transfer and storage in quantum communication platforms.
Physical Review B, 2010
Semiconductor microcavities play a key role in connecting exciton states and photons in advancing quantum information in solids. In this work we report on coherent interaction between high quality microcavity photon modes and spin states of a quantum dot in the strong coupling regime of cavity quantum electrodynamics. The coupling between the photon and exciton modes is studied by varying the temperature, where the spin states are resolved with a magnetic field applied in Faraday configuration. A detailed oscillator model is used to extract coupling parameters of the individual spin and cavity modes, which shows that the coupling depends on features of the mode symmetries. Our results demonstrate an effective coupling between photon modes that is mediated by the exciton spin states.