Ultrafast few-fermion optoelectronics in a single self-assembled<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mtext>In</mml:mtext><mml:mtext>Ga</mml:mtext><mml:mtext>As</mml:mtext><mml:mo>/</mml:mo><mml:mtext>GaAs</mml:mtext></mml:mrow></mml:math>quantum dot

Zecherle, M.; Ruppert, Claudia; Clark, E. C.; Abstreiter, G.; Finley, Jonathan J.; Betz, M.

doi:10.1103/physrevb.82.125314

Cited by 28 publications

(31 citation statements)

References 30 publications

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“…We note here that all data presented throughout this manuscript were obtained at a lattice temperature of T = 4.2 K. For the remainder of the manuscript we focus on resonant fluorescence (RF) spectroscopy with linearly crosspolarised suppression of the excitation laser as described in detail in references [29,30]. Thereby, we used a fspulsed Ti:Sa laser and 4f pulse-shaping to obtain tunable picosecond pulses with a temporal bandwidth of ∼ 10 ps [10,20,31] corresponding to a spectral bandwidth of ∼ 0.22 meV . The luminescence intensity obtained from the neutral exciton X 0 under resonant pulsed excitation is presented in figure 1b for a fixed bias of V gate = 0.175 V .…”

mentioning

confidence: 99%

Dissipative preparation of the exciton and biexciton in self-assembled quantum dots on picosecond time scales

Ardelt

Hanschke²,

Fischer³

et al. 2014

Phys. Rev. B

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Pulsed resonant fluorescence is used to probe ultrafast phonon-assisted exciton and biexciton preparation in individual self-assembled InGaAs quantum dots. By driving the system using large area (≥ 10π) near resonant optical pulses, we experimentally demonstrate how phonon mediated dissipation within the manifold of dressed excitonic states can be used to prepare the neutral exciton with a fidelity ≥ 70%. By comparing the phonon-assisted preparation with resonant Rabi oscillations we show that the phonon-mediated process provides the higher fidelity preparation for large pulse areas and is less sensitive to pulse area variations. Moreover, by detuning the laser with respect to the exciton transition we map out the spectral density for exciton coupling to the bulk LA-phonon continuum. Similar phonon mediated processes are shown to facilitate direct biexciton preparation via two photon biexciton absorption, with fidelities > 80%. Our results are found to be in very good quantitative agreement with simulations that model the quantum dot-phonon bath interactions with Bloch-Redfield theory.Due to their discrete electronic structure and strong interaction with light, self-assembled quantum dots (QDs) are often described as artificial atoms in the solid state. Indeed, many quantum optical experiments have recently been performed that exploit these atom-like properties; specific examples including deterministic single [11][12][13]. Moreover, in cavity QED experiments [14] remarkable effects such as photonblockade or photon-tunneling have opened the way to exploit QDs to generate novel quantum states of light [15]. In all these experiments, the solid state environment of the QDs manifests itself primarily in coupling to acoustic phonons -an effect that is unwanted since it results in decoherence of the quantum state, particular examples include incoherent population transfer between a QD and a detuned microcavity mode [16] or intra-molecular tunneling in vertically stacked QD-molecules [17,18]. Moreover, in coherent optical exciton control experiments, coupling to acoustic phonons dominates the damping of Rabi oscillations [19,20], limiting state preparation and control fidelities and the scope for possible applications. However, in other cases the coupling to acoustic phonons was exploited instead, e.g. for the high-fidelity spin initialisation by tunnel ionisation [21] or for achieving population inversion in electrically driven quantum dots [22]. Recently, Glässl et al. [23] proposed that high-fidelity preparation of excitonic states could be achieved by exploiting the coupling of the dressed excitonic states to a quasi continuum of vibrational modes. Their approach involves to combining the relative advantages of both Rabi oscillations and rapid adiabatic passage [24,25] by making use of phonon-mediated relaxation in the presence of a strong, near resonant pulsed optical field.In this paper we investigate the phonon-assisted preparation of neutral exciton (X 0 ) and biexciton (2X) states in QDs using pulsed resonant...

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mentioning

confidence: 99%

Dissipative preparation of the exciton and biexciton in self-assembled quantum dots on picosecond time scales

Ardelt

Hanschke²,

Fischer³

et al. 2014

Phys. Rev. B

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“…In addition, a pronounced negative going dip (pump induced bleaching) is observed at the energy of X at 1310.3 meV. The observed pump-probe spectra can be understood with the level scheme depicted schematically in Fig.3b [17][18][19]. The pump pulse generates an exciton in the upper QD (left part Fig.3b) and, providing that the delay between pump and probe is less than the timescales for electron and hole tunneling, the probe pulse can further excite the system to generate the spatially direct biexciton (right part Fig.3b).…”

Section: Probing Few Fermion Transitionsmentioning

confidence: 81%

Probing ultrafast charge and spin dynamics in a quantum dot molecule

Müller¹,

Bechtold²,

Ruppert

et al. 2012

SPIE Proceedings

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We apply ultrafast pump-probe photocurrent spectroscopy to directly probe few Fermion charge and spin dynamics in an artificial molecule formed by vertically stacking a pair of InGaAs self-assembled quantum dots. As the relative energy of the orbital states in the two dots are energetically tuned by applying static electric fields, pronounced anticrossings are observed arising from electron tunnel couplings. Time resolved photocurrent measurements performed in the vicinity of these anticrossings provide direct information on the comparative roles of elastic and inelastic resonant tunneling processes between the two quantum dots forming the molecule. Resonant pumping of the neutral exciton in the upper dot with circularly polarized light facilitates ultrafast initialization of hole spin qubits over timescales limited only by the laser pulse duration (<5ps) and a near perfect Pauli spin-blockade with a near unity suppression of absorption (>96%) for spin forbidden transitions. Such a spin selective photocurrent response opens the way to probe spin dynamics in the system over ultrafast timescales. VERTICALLY STACKED QUANTUM DOT MOLECULESQuantum dot (QD) nanostructures formed by strain driven self-assembly are ideal for solid state quantum optics experiments due to their discrete optical spectrum, strong interaction with light and robust quantum coherence for both interband polarization [1,2] and spin [3]. The ease with which such nanostructures can be embedded into electrically active devices allows for tuning of the transition frequency and control of charge occupancy [4]. Vertically stacking of optically active QDs produces QD-molecules (QDMs) which exhibit strong electrically tunable dot-dot tunnel coupling when electronic states in the different dots are tuned into resonance. These couplings result in anticrossings of the corresponding exciton transitions that can be observed in optical experiments [5][6][7]. Tunnel coupling occurs either for electrons or holes [8], depending on the relative dot size and couplings between different orbital states can occur due to symmetry breaking [9]. Whilst photoluminescence measurements have revealed a large tuneability of static properties such as Landé g-factors [10,11] or spin dependent couplings (singlet-triplet splittings) [7,12] dynamic properties can only be indirectly studied by comparing the data with models [13,14]. The impact of tunnel coupling on the ultrafast intra-molecular carrier dynamics remains practically unexplored Electrically controlled coupling in vertically stacked quantum dot moleculesThe sample consists of a vertically stacked pair of self-assembled InGaAs quantum dots separated by a 10nm thick GaAs spacer and embedded within the intrinsic region of a GaAs Schottky photodiode. This device permits complementary photocurrent (PC) and photoluminescence (PL) measurements by varying the potential applied to the contacts that

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“…III B is an encouraging milestone on our path toward measuring FWM and multi-dimensional spectra from few nano-objects, especially when considering the prevalence of photocurrent measurements reported in the literature for single QDs, 41,42 nanowires, [43][44][45] and carbon nanotubes. 46 In particular, understanding coherent coupling mechanisms between the QDs of an ensemble 47 would be an important step towards scalable QD exciton-based quantum information processors.…”

Section: Perspectives For the Collinear Setupmentioning

confidence: 98%

Multi-dimensional coherent optical spectroscopy of semiconductor nanostructures: Collinear and non-collinear approaches

Nardin

Autry

Singh

et al. 2015

Journal of Applied Physics

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We review our recent work on multi-dimensional coherent optical spectroscopy (MDCS) of semiconductor nanostructures. Two approaches, appropriate for the study of semiconductor materials, are presented and compared. A first method is based on a non-collinear geometry, where the Four-Wave-Mixing (FWM) signal is detected in the form of a radiated optical field. This approach works for samples with translational symmetry, such as Quantum Wells (QWs) or large and dense ensembles of Quantum Dots (QDs). A second method detects the FWM in the form of a photocurrent in a collinear geometry. This second approach extends the horizon of MDCS to sub-diffraction nanostructures, such as single QDs, nanowires, or nanotubes, and small ensembles thereof. Examples of experimental results obtained on semiconductor QW structures are given for each method. In particular, it is shown how MDCS can assess coupling between excitons confined in separated QWs.

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Ultrafast few-fermion optoelectronics in a single self-assembledInGaAs/GaAsquantum dot

Cited by 28 publications

References 30 publications

Dissipative preparation of the exciton and biexciton in self-assembled quantum dots on picosecond time scales

Dissipative preparation of the exciton and biexciton in self-assembled quantum dots on picosecond time scales

Probing ultrafast charge and spin dynamics in a quantum dot molecule

Multi-dimensional coherent optical spectroscopy of semiconductor nanostructures: Collinear and non-collinear approaches

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