Transient Reflection: A Versatile Technique for Ultrafast Spectroscopy of a Single Quantum Dot in Complex Environments

Wolpert, Christian; Dicken, Christian; Atkinson, P.; Wang, Limin; Rastelli, Armando; Schmidt, Oliver G.; Gießen, Harald; Lippitz, Markus

doi:10.1021/nl203804n

Cited by 14 publications

(9 citation statements)

References 33 publications

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“…Two complete cycles of the Rabi oscillation are visible. They show, in contrast to the textbook example, a gradual stretching of the oscillation period 21.…”

Section: Rabi Oscillations In a Quantum Dot On An Absorbing Substratecontrasting

confidence: 71%

“…All these techniques render the fascinating plasmonic nanocircuits discussed above impossible in the worst case or at least hinder them. We demonstrate that far‐field reflection spectroscopy is sufficient to gain not only ultrafast spectroscopic information of single QDs without further restrictions to the structure design 21, but is also capable to obtain control of the quantum state of the dots by all‐optical means. This allows for interesting future experiments with QDs in complex systems.…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast coherent spectroscopy of a single self‐assembled quantum dot

Wolpert

Dicken

Wang

et al. 2012

Physica Status Solidi (b)

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The controlled interaction of several quantum dots (QDs) mediated by plasmonic or photonic nanostructures promises interesting new functionality in the fields of quantum computing and telecommunication. Ultrafast laser pulses can be used to write and read out the state of the QD. We review ultrafast coherent spectroscopy of single QDs. The focus of this article is on the technique of transient reflection spectroscopy which can be applied to a broad range of samples and devices. It only requires optical access to a single quantum system next to a reflecting surface. We demonstrate the versatility of our approach by presenting several quantum optical studies such as Rabi oscillations, perturbed free induction decay, and quantum beats from an entangled excitonic state in weakly absorbing GaAs QDs. We expect this experimental method to make coherent experiments possible in elaborate devices where quantum emitters are interacting with a complex environment such as plasmonic waveguides or antennas. 1 Introduction In recent years substantial efforts were made to produce matter quantum bits (standing qubits) in various systems [1]. These quantum mechanical two-level systems can be realized by atom-like systems such as single molecules, nitrogen vacancy centers in diamond or semiconductor quantum dots (QDs). Photons are acting as flying quantum bits (qubits) which can be used to transfer quantum information from one stationary qubit to the next and in this way form the connections in a quantum network. Artificial atoms are coupled to cavities or waveguides in order to establish an interface between photons and excitations in matter. In order to produce new photonic devices with novel functionalities one needs not only an efficient quantum system that can be addressed by photons but also controlled coupling to the interconnects.Semiconductor QDs are appealing systems in this context as they are a pure solid-state system which makes them stable, long-lived, and compatible with conventional 2D fabrication techniques. Dephasing times of neutral excitons in QDs can be on the order of several hundreds of

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“…Two complete cycles of the Rabi oscillation are visible. They show, in contrast to the textbook example, a gradual stretching of the oscillation period 21.…”

Section: Rabi Oscillations In a Quantum Dot On An Absorbing Substratecontrasting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Ultrafast coherent spectroscopy of a single self‐assembled quantum dot

Wolpert

Dicken

Wang

et al. 2012

Physica Status Solidi (b)

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“…In this context and the context of the single-photon amplifier, it is important to understand the intrinsic relaxation mechanisms which can influence preparation and readout of the few-particle quantum states via ultrashort light pulses. To this end, charge-carrier dynamics in QDs based on III-V semiconductors with shallow quantum confinement has been studied both in large ensembles [18][19][20] and single specimens [7,[21][22][23][24][25][26]. These developments have culminated in demonstrations of optical writing and readout of spin states in single or coupled QDs [13][14][15][16][17]27].…”

Section: Introductionmentioning

confidence: 99%

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

et al. 2018

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We study the dynamics of photoexcited electrons and holes in single negatively charged CdSe/ZnSe quantum dots with two-color femtosecond pump-probe spectroscopy. An initial characterization of the energy level structure is performed at low temperatures and magnetic fields of up to 5 T. Emission and absorption resonances are assigned to specific transitions between few-fermion states by a theoretical model based on a configuration interaction approach. To analyze the dynamics of individual charge carriers, we initialize the quantum system into excited trion states with defined energy and spin. Subsequently, the time-dependent occupation of the trion ground state is monitored by spectrally resolved differential transmission measurements. We observe subpicosecond dynamics for a hole excited to the D shell. The energy dependence of this D-to-S shell intraband transition is investigated in quantum dots of varying size. Excitation of an electron-hole pair in the respective p shells leads to the formation of singlet and triplet spin configurations. Relaxation of the p-shell singlet is observed to occur on a time scale of a few picoseconds. Pumping of p-shell triplet transitions opens up two pathways with distinctly different scattering times. These processes are shown to be governed by the mixing of singlet and triplet states due to exchange interactions enabling simultaneous electron and hole spin flips. To isolate the relaxation channels, we align the spin of the residual electron by a magnetic field and employ laser pulses of defined helicity. This step provides ultrafast preparation of a fully inverted trion ground state of the quantum dot with near unity probability, enabling deterministic addition of a single photon to the probe pulse. Therefore our experiments represent a significant step towards using single quantum emitters with well-controled inversion to manipulate the photon statistics of ultrafast light pulses.

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“…It was previously applied to lateral GaAs interface fluctuation QDMs 16 using a scanning near‐field microscope. We carried out ultrafast coherent spectroscopy of a single QDM using a double modulation scheme 12. Orthogonal linearly polarized pump‐ and probe pulses are obtained from a mode‐locked Ti:sapphire laser having a pulse duration of about 150 fs.…”

Section: Rabi Flopping Of a Single Exciton Transition In A Qdmmentioning

confidence: 99%

“…All operations on the quantum register need to be completed within the coherence time of the quantum dot which is typically in the order of some tens to hundreds of picoseconds 10, 11. In this article we present ultrafast transient reflection spectroscopy 12 on a single InGaAs quantum dot molecule.…”

Section: Introductionmentioning

confidence: 99%

Transient absorption spectroscopy of a single lateral InGaAs quantum dot molecule

Wolpert

Wang

Rastelli

et al. 2012

Physica Status Solidi (b)

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Lateral quantum dot molecules promise a scalable approach to quantum registers. The individual neutral exciton states can be controlled by a lateral bias voltage. In this way radiative emission of localized excitons can be switched between the two quantum dots in the molecule. Here, we report on coherent absorption spectroscopy of a single quantum dot molecule. By transient reflection spectroscopy we demonstrate that not only the emission but also the absorption switches from one dot to the other when varying the applied electric field. This result is consistent with Rabi flopping showing a radically suppressed dipole moment for the non-emitting exciton transition ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Self-assembled quantum dot molecules (QDMs) were studied extensively in recent years due to their potential application as basic building blocks in quantum computation [1] and as tunable singlephoton sources [2]. Individual neighboring quantum dots are coupled in a controlled way by shifting their excitonic states with gate electrodes via the Stark effect. Vertically arranged QDMs [3-5] make the application of individual electrodes technologically demanding and the upscaling to larger quantum registers problematic. An attractive alternative are laterally coupled quantum dot molecules [6]. Their planar geometry allows for coupling in two directions and makes upscaling of the system conceptually straight-forward. Connections between individual QDMs can be realized by plasmonic wires [7] and waveguides [8].While a signature of the coupling between the quantum dots in the QDM is observable in steady-state photoluminescence, an application of the QDM in the field of quantum computing requires ultrafast spectroscopy [9]. All operations on the quantum register need to be completed within the coherence time of the quantum dot which is typically in the order of some tens to hundreds of picoseconds [10,11]. In this article we present ultrafast transient reflection spectroscopy [12] on a single InGaAs quantum dot molecule.

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Transient Reflection: A Versatile Technique for Ultrafast Spectroscopy of a Single Quantum Dot in Complex Environments

Cited by 14 publications

References 33 publications

Ultrafast coherent spectroscopy of a single self‐assembled quantum dot

Ultrafast coherent spectroscopy of a single self‐assembled quantum dot

Charge and spin control of ultrafast electron and hole dynamics in single CdSe/ZnSe quantum dots

Transient absorption spectroscopy of a single lateral InGaAs quantum dot molecule

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