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2022, Physical Review Letters
We develop an exact analytical approach to the optical response of a quantum dot-microcavity system for arbitrary excitation strengths. The response is determined in terms of the complex amplitudes of transitions between the rungs of the Jaynes-Cummings ladder, explicitly isolating nonlinearities of different orders. Increasing the pulse area of the excitation field, we demonstrate the formation of a quantum Mollow quadruplet (QMQ), quantizing the semi-classical Mollow triplet into a coherent superposition of a large number of transitions between rungs of the ladder, with inner and outer doublets of the QMQ formed by densely lying inner and outer quantum transitions between the split rungs. Remarkably, a closed-form analytic approximation for the QMQ of any order of nonlinearity is found in the high-field low-damping limit.
Nature Materials, 2010
In spite of their different natures, light and matter can be unified under the strong-coupling regime, yielding superpositions of the two, referred to as dressed states or polaritons. After initially being demonstrated in bulk semiconductors 1 and atomic systems 2 , strong-coupling phenomena have been recently realized in solid-state optical microcavities 3 . Strong coupling is an essential ingredient in the physics spanning from many-body quantum coherence phenomena, such as Bose-Einstein condensation 4 and superfluidity 5 , to cavity quantum electrodynamics. Within cavity quantum electrodynamics, the Jaynes-Cummings model 6-8 describes the interaction of a single fermionic two-level system with a single bosonic photon mode. For a photon number larger than one, known as quantum strong coupling, a significant anharmonicity is predicted for the ladder-like spectrum of dressed states. For optical transitions in semiconductor nanostructures, first signatures of the quantum strong coupling were recently reported 9 . Here we use advanced coherent nonlinear spectroscopy to explore a strongly coupled exciton-cavity system 10,11 . We measure and simulate its four-wave mixing response 12,13 , granting direct access to the coherent dynamics of the first and second rungs of the Jaynes-Cummings ladder. The agreement of the rich experimental evidence with the predictions of the Jaynes-Cummings model is proof of the quantum strong-coupling regime in the investigated solid-state system.
Physical Review B, 2008
The optical emission spectrum of a quantum dot in strong coupling with the single mode of a microcavity is obtained in the nonlinear regime. We study how exciton-exciton interactions alter the emission spectrum of the system, bringing the linear Rabi doublet into a multiplet structure that is strongly dependent on the cavity-exciton energy detuning. We emphasise how nonlinearity can be used to evidence the genuine quantum nature of the coupling by producing satellites peaks of the Rabi doublet that originate from the quantized energy levels of the interactions.
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.
Physical Review B, 2010
We investigate theoretically two-photon processes in a microcavity containing one quantum dot in the strong coupling regime. The cavity mode can be tuned to resonantly drive the two-photon transition between the ground and the biexciton states, while the exciton states are far-off resonance due to the biexciton binding energy. We study the steady state of the quantum dot and cavity field in presence of a continuous incoherent pumping. We identify the regime where the system acts as two-photon emitter and discuss the feasibility and performance of realistic single quantum dot devices for two-photon lasing.
Proceedings of SPIE, 2012
We analyze the impact of both an incoherent and a coherent continuous excitation in our proposal to generate a two-photon state from a quantum dot in a microcavity [New J. Phys. 13, 113014 (2011)]. A comparison between exact numerical results and analytical formulas provides the conditions to efficiently generate indistinguishable and simultaneous pairs of photons under both types of excitation.
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.
Physical Review B, 2015
We demonstrate the emission of highly indistinguishable photons from a quasi-resonantly pumped coupled quantum dot-microcavity system operating in the regime of cavity quantum electrodynamics. Changing the sample temperature allows us to vary the quantum dot-cavity detuning and, on spectral resonance, we observe a threefold improvement in the Hong-Ou-Mandel interference visibility, reaching values in excess of 80%. Our measurements off-resonance allow us to investigate varying Purcell enhancements, and to probe the dephasing environment at different temperatures and energy scales. By comparison with our microscopic model, we are able to identify pure dephasing and not time jitter as the dominating source of imperfections in our system.
2011
We discuss the spectral lineshapes of N quantum dots in strong coupling with the single mode of a microcavity. Nontrivial features are brought by detuning the emitters or probing the direct exciton emission spectrum. We describe dark states, quantum nonlinearities, emission dips and interferences and show how these various effects may coexist, giving rise to highly peculiar lineshapes.
2013
Charge-neutral excitons in semiconductor quantum dots have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, thus generalizing the Mollow triplet to become a Mollow quintuplet. We experimentally confirm such spectral quintuplets for In(Ga)As quantum dots and obtain very good agreement with theory.
Physica E: Low-dimensional Systems and Nanostructures, 2009
Cooperative exciton-photon dynamics of a linear chain consisting of closely spaced quantum dots has been studied numerically in the simplified Jaynes-Cummings model with dipole-dipole interaction and only nearest neighbor interactions. In the aggregate, quantum dots are assumed to be coupled with a single mode field of a perfect microcavity. In the chain, the transport of the excitation energy via resonance dipole-dipole interaction generates propagating exciton-waves which interfere with themselves in the mediation of photon field. We show that the absorption and emission of the field is inhibited or enhanced depending on system parameters and the excitation of specified quantum dots is also suppressed or enforced depending on dipole-dipole coupling constant.
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.
2009
This work has been withdrawn as we wish to rework and clarify several aspects of the paper. A related and reworked paper will be submitted at a later date.
New Journal of Physics, 2011
We analyze the impact of both an incoherent and a coherent continuous excitation in our proposal to generate a two-photon state from a quantum dot in a microcavity [New J. Phys. 13, 113014 (2011)]. A comparison between exact numerical results and analytical formulas provides the conditions to efficiently generate indistinguishable and simultaneous pairs of photons under both types of excitation. arXiv:1201.0284v1 [cond-mat.mes-hall] 31 Dec 2011 * In fact, this is an alternative way to estimate κ1P, κ2P, and then g1P, g2P with Eq. (4). The effective photonic decay rate of |H1 is its photonic component |C1P| 2 times the associated decay rate κ, etc. † One can estimate them by comparing populations ρV,V and ρB,B in Eq. (9), to second order in 1/χ, with the occupation of a two-level system in the linear regime, given by 4Ω 2 /Γ, with Γ its decay rate.
Journal of Modern Optics, 2021
We theoretically investigate optical bistability, mechanically induced absorption (MIA) and Fano resonance of a hybrid system comprising of a single quantum dot (QD) embedded in a solid state microcavity interacting with the quantized cavity mode and the deformation potential associated with the lattice vibration. We find that the bistability can be tuned by the QD-cavity mode coupling. We further show that the normalized power transmission displays anomalous dispersion indicating that the system can be used to generate slow light. We also demonstrate the possibility of using the system as all optomechanical Kerr switch.
2006
A single atom in a cavity is the model system of cavity quantum electrodynamics (CQED). The strong coupling regime between the atom and cavity-confined photon corresponds to the reversible exchange of energy between the two modes, and underpins a wide range of CQED phenomena with applications in quantum information science, including for example as quantum logic gates and as sources of entangled states. 2,3,4 An important advance was achieved recently when strong coupling between excitons and cavity photons was reported for the first time for localized quantum dots (QDs) in micron-size solid state cavities, 5-8 . This has significance in terms of scalability and integration with other optical devices, and could lead to the emergence of 'quantum optics on a chip' technology. However the results presented so far for quantum dots are in the linear regime, corresponding to coupling to the vacuum field (vacuum Rabi splitting); they are not a true QED effect and can equally well be described by classical physics as the coupling between two oscillators. 9 In this paper, we present evidence for a purely quantum phenomenon for the QD/cavity photon system, namely the increase in splitting of the levels when the mean number of photons in the cavity is increased. This corresponds to non-linearities on the single-photon scale: the presence of a single excitation in the cavity changes the level structure, affecting the emission energies for a second photon. Such results are a first step in demonstrating the promise of quantum dots for CQED applications.
Nature Photonics, 2012
Emission from a resonantly excited quantum emitter is a fascinating research topic within the field of quantum optics and is a useful source for different types of quantum light fields. The resonance spectrum consists of a single spectral line that develops into a triplet above saturation of the quantum emitter. The three closely spaced photon channels from the resonance fluorescence
Physical Review Letters, 2011
We measure the detuning-dependent dynamics of a quasi-resonantly excited single quantum dot coupled to a micropillar cavity. The system is modeled with the dissipative Jaynes-Cummings model where all experimental parameters are determined by explicit measurements. We observe non-Markovian dynamics when the quantum dot is tuned into resonance with the cavity leading to a non-exponential decay in time. Excellent agreement between experiment and theory is observed with no free parameters providing the first quantitative description of an all-solid-state cavity QED system based on quantum dot emitters.
Physica E: Low-dimensional Systems and Nanostructures, 2006
We theoretically study the coupled modes of a medium-size quantum dot, which may confine a maximum of ten electron-hole pairs, and a single photonic mode of an optical microcavity. Groundstate and excitation energies, exciton-photon mixing in the wave functions and the emission of light from the microcavity are computed as functions of the pair-photon coupling strength, photon detuning, and polariton number.
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.
Nature, 2008
The already very active field of cavity quantum electrodynamics (QED), traditionally studied in atomic systems , has recently gained additional momentum by the advent of experiments with semiconducting [4, 5, 6, 7, 8] and superconducting [9, 10, 11] systems. In these solid state implementations, novel quantum optics experiments are enabled by the possibility to engineer many of the characteristic parameters at will. In cavity QED, the observation of the vacuum Rabi mode splitting is a hallmark experiment aimed at probing the nature of matter-light interaction on the level of a single quantum. However, this effect can, at least in principle, be explained classically as the normal mode splitting of two coupled linear oscillators . It has been suggested that an observation of the scaling of the resonant atom-photon coupling strength in the Jaynes-Cummings energy ladder with the square root of photon number n is sufficient to prove that the system is quantum mechanical in nature . Here we report a direct spectroscopic observation of this characteristic quantum nonlinearity. Measuring the photonic degree of freedom of the coupled system, our measurements provide unambiguous, long sought for spectroscopic evidence for the quantum nature of the resonant atom-field interaction in cavity QED. We explore atom-photon superposition states involving up to two photons, using a spectroscopic pump and probe technique. The experiments have been performed in a circuit QED setup , in which ultra strong coupling is realized by the large dipole coupling strength and the long coherence time of a superconducting qubit embedded in a high quality on-chip microwave cavity. Circuit QED systems also provide a natural quantum interface between flying qubits (photons) and stationary qubits for applications in quantum information processing and communication (QIPC) .
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