Dynamically Controlled Resonance Fluorescence Spectra from a Doubly Dressed Single InGaAs Quantum Dot

Abstract

We report the first experimental demonstration of the interference-induced spectral line elimination predicted by Zhu and Scully [Phys. Rev. Lett. 76, 388 (1996)] and Ficek and Rudolph [Phys. Rev. A 60, R4245 (1999)]. We drive an exciton transition of a self-assembled quantum dot in order to realize a twolevel system exposed to a bichromatic laser field and observe the nearly complete elimination of the resonance fluorescence spectral line at the driving laser frequency. This is caused by quantum interference between coupled transitions among the doubly dressed excitonic states, without population trapping. We also demonstrate a multiphoton ac Stark effect with shifted subharmonic resonances and dynamical modifications of resonance fluorescence spectra by using double dressing. New physics beyond the Mollow fluorescence triplet arises when a two-level system is exposed to strong bichromatic driving fields, exhibiting a range of nonlinear and multiphoton dynamics of light-matter interaction [22,23]. In particular, it has been pointed out that a dynamical cancellation of the spontaneous emission spectral line, initially predicted for a three-level system [24,25], may be possible in a two-level atom [26,27], which is not due to population trapping, but induced by quantum interferences between different transition channels in a doubly dressed atom. This occurs when a two-level atom is driven by a strong resonant laser with a Rabi frequency 2Ω [28], and a second, weaker laser is detuned by 2Ω from the strong field. The suppression of spontaneous emission spectral lines also appears when the second laser is coupled to the shifted subharmonics of 2Ω, which can be attributed to the multiphoton ac Stark effect [22]. Despite the extensive efforts undertaken to observe this phenomenon [29][30][31][32][33][34], the experimental demonstration of a complete cancellation of spontaneous emission lines has been claimed once in a V-type level atom [29], where there was also an alternative interpretation based on population trapping possible [32]. Here, we use a single QD, doubly dressed by bichromatic fields, to demonstrate unequivocally the complete cancellation of spontaneous emission spectral lines and other features arising from this phenomenon including shifted subharmonic resonances and modifications of sideband spectra.Our experiments are carried out on self-assembled InGaAs QDs embeded in a low-Q planar microcavity (Q ≈ 200) and housed in a cryogen-free bath cryostat operating at 4.2 K, as shown in Fig. 1(a). The measurements are performed on the neutral exciton transition of a single QD with a confocal microscope allowing bichromatic excitations of the QD from the side arm and collection of PRL 114, 097402 (2015) P H Y S I C A L

Highly efficient two-photon generation from a coherently pumped quantum dot embedded in a microcavity

“…Further in strong driving limit the peak corresponding to ω − ω c = ∆ 2 , splits into other peaks. The appearance of many peaks at ω − ω c = ∆ 2 can we understood using dressed state picture 27 .…”

Efficient control of coulomb enhanced second harmonic generation from excitonic transitions in quantum dot ensembles

“…Regarding dynamic control of the nonlinear response, [40,41] this actually represents an advantage of such interband scheme as compared to intraband systems where the presence of confined carriers in the quantum dot ensemble is achieved by conventional doping. Furthermore if compared to systems where population is controlled by gate voltages, [42] this optically activated occupation of the dots seems still more efficient and deterministic, because using voltages to depopulate may require very strong fields to deplete deeply bound states (far below the band offset).…”

Engineering a squeezed phonon reservoir with a bichromatic driving of a quantum dot

“…A number of different situations have been investigated [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. These include experimental studies of the effect of phonons on the Rabi oscillations, Autler-Townes splitting, and the Mollow triplet of the fluorescence field emitted by a driven quantum dot [16][17][18][19][20][21][22][23][24]. In particular, it has been observed that the linewidths of the Rabi sidebands of the Mollow triplet increase linearly with temperature and with the square of the driving field strength [25,26].…”