Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

Figures & data

Figure 1. Left: Transmission electron microscopy (TEM) picture of a cross section of a single InGaAs QD. Figure by A. Ludwig and J-M. Chauveau [94]${ }^{\copyright }$ Nature Publishing Group. Center: Calculated phonon spectral density for a spherical QD with a size of $3.8$ nm and a flat QD with a lateral size of $5$ nm and a height of $1.5$ nm. Right: Measured effective phonon spectral density (dots) fitted by a theoretical calculation. The measurements were taken at $T=10$ K. The inset shows the calculated effective phonon spectral density for different temperatures. The right part is taken from [100]${ }^{\copyright }$ American Physical Society.

Figure 2. Left: Calculated normalized emission spectrum from a single QD at different temperatures. Note the logarithmic scale. Inset: fraction of the intensity in the sidebands. Taken from Ref [163].${ }^{\copyright }$ American Physical Society. Right: Calculated spectrum from a QD in a photonic cavity (red dotted line) and without cavity (black line). The cavity spectrum is indicated by the blue, dashed line. Note the logarithmic scale. Taken from Ref [168].${ }^{\copyright }$ American Physical Society.

Figure 3. Top: Exciton occupation in a two-level QD coupled to phonons as a function of time and excitation strength for a continuous excitation with the Rabi frequency ${\mathrm{\Omega }}_R$ switched on instantaneously at $t=0$. Bottom: Normalized phonon displacement $\tilde{u}$ at a sphere outside the QD. The dashed lines mark the resonance with the maximum of the phonon spectral density. Results adopted from [118] ${ }^{\copyright }$ IOP Publishing. Right: Dynamics of the Bloch vector on the Bloch sphere for the phonon-damped Rabi oscillations.

Figure 4. (a) Experimentally measured fluorescence and (b) theoretically calculated occupation corresponding to the excited state of a QD driven by a chirped laser pulse with different chirp rates as indicated. Taken from [206]${ }^{\copyright }$ American Physical Society.

Figure 5. Left: Phonon-assisted state preparation using two-photon excitation (TPE) for different laser detunings and two excitation strength $1\pi$ and $7\pi$. Dots are experimental data, while the solid lines are fits. Taken from [218] under a Creative Commons Attribution. Right: Dynamics of the Bloch vector for phonon-assisted state preparation with (a,b) dynamics of the Bloch sphere and (c,d) length of the Bloch vector for excitation with a Gaussian pulse (a,c) and with a rectangular pulse with either a smooth switch on (blue) or off (red) (b,d). Taken from [202] ${ }^{\copyright }$ American Physical Society.

Figure 6. Impact of the temperature on the two-photon interference (TPI) visibility. (a)-(c) TPI histograms for co-polarized configuration at 10, 25, and 35 K and corresponding fits (red solid curves). (d) Experimentally obtained TPI visibilities for various temperatures together with theoretical results accounting for two stochastic forces. Taken from Ref [257].${ }^{\copyright }$ American Physical Society.

Figure 7. Brightness $\mathcal{B}$ (panels a, b) and single-photon purity $\mathcal{P}$ (panels c, d) as a function of the excitation pulse area $\theta$ of a pulse in the pulse train for selected laser-exciton detunings $\mathrm{\Delta }{\omega }_{LX}$. The left column (a, c) is the result of a phonon-free calculation, the right column (b, d) includes the coupling to a continuum of LA phonons. The purity curves have been cut off at the lower end at 50% in order to highlight the behavior at elevated $\mathcal{P}$ values. Results are taken from [288].

Figure 8. Cavity photon distribution at $t$ = 3 ns for different detunings $\delta$ and a cavity coupling $\mathrm{\hslash }g=0.1$ meV equal to the laser driving strength. (a) without dot-phonon interaction and (b) with phonons at temperature $T$ = 4 K. (c) Photon distribution at detuning $\delta =-18\mu$eV with phonons at $T$ = 4 K compared with Poissonian and thermal distributions. Figure taken from [37] © American Physical Society.

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