Energy transport and coherence properties of acoustic phonons generated by optical excitation of a quantum dot

Wigger, Daniel; Lüker, Sebastian; Reiter, Doris E.; Axt, Vollrath M.; Machnikowski, Paweł; Kuhn, Thomas

doi:10.1088/0953-8984/26/35/355802

Cited by 29 publications

(62 citation statements)

References 55 publications

(137 reference statements)

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“…The pulse area θ in Eq. (14) determines to which amount the system is brought into the excited state and, therefore, which fraction of the phonon state switches into the shifted potential. A nonvanishing decay rate of the excited state makes the phonons go back to the unshifted potential associated with the ground state of the TLS as depicted in Let us start by considering the excitation by a pulse with θ = π in a system with an electron-phonon coupling constant γ = 2 and an excited state decay constant Γ = 0.5 ω ph .…”

Section: A Single-pulse Excitationmentioning

confidence: 99%

Influence of excited state decay and dephasing on phonon quantum state preparation

et al. 2019

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The coupling between single-photon emitters and phonons opens many possibilities to store and transmit quantum properties. In this paper we apply the independent boson model to describe the coupling between an optically driven two-level system and a discrete phonon mode. Tailored optical driving allows not only to generate coherent phonon states, but also to generate coherent superpositions in the form of Schrödinger cat states in the phonon system. We analyze the influence of decay and dephasing of the two-level system on these phonon preparation protocols. We find that the decay transforms the coherent phonon state into a circular distribution in phase space. Although the dephasing between two exciting laser pulses leads to a reduction of the interference ability in the phonon system, the decay conserves it during the transition into the ground state. This allows to store the phonon quantum state properties in the ground state of the single-photon emitter.

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Section: A Single-pulse Excitationmentioning

confidence: 99%

Influence of excited state decay and dephasing on phonon quantum state preparation

et al. 2019

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“…For higher pulse areas, theory predicts that the electronic oscillations become so fast such that the phonons decouple and the Rabi oscillations recover, the reappearance phenomenon. The existence of a pulse area for which the coupling to the phonons is maximal is a consequence of the nonmonotonic electron-phonon coupling [1,16].For the pulses used so far experimentally (pulses of 1-10 ps duration), the reappearance regime for Rabi oscillations can only be entered at extremely high pulse areas (>20π ) and has therefore remained out of reach. We switch to an alternative technique here, rapid adiabatic passage (RAP) [17][18][19][20][21][22][23][24][25], and use the full bandwidth of 100 fs pulses.…”

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Demonstrating the decoupling regime of the electron-phonon interaction in a quantum dot using chirped optical excitation

et al. 2017

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Excitation of a semiconductor quantum dot with a chirped laser pulse allows excitons to be created by rapid adiabatic passage. In quantum dots this process can be greatly hindered by the coupling to phonons. Here we add a high chirp rate to ultrashort laser pulses and use these pulses to excite a single quantum dot. We demonstrate that we enter a regime where the exciton-phonon coupling is effective for small pulse areas, while for higher pulse areas a decoupling of the exciton from the phonons occurs. We thus discover a reappearance of rapid adiabatic passage, in analogy to the predicted reappearance of Rabi rotations at high pulse areas. The measured results are in good agreement with theoretical calculations. DOI: 10.1103/PhysRevB.95.241306 In semiconductors, a driven electron is damped by the interaction with phonons. In the context of quantum control, phonons lead to dephasing. The electron-phonon interaction is therefore important in the development of quantum technology with semiconductors. It is a rich and subtle subject.One possible way to suppress electron-phonon damping is to drive the electronic system so quickly that the relatively large inertia of the phonons prevents them from reacting to the driven electron. In the context of Rabi oscillations, the driven oscillations of a two-level system, a "reappearance" has been predicted [1]. As the drive is increased, the Rabi oscillations are initially damped more and more by the phonons, but then the damping decreases and is eventually suppressed. The reappearance regime represents phonon-free quantum control. It has, however, never been observed experimentally. Here, we demonstrate the experimental realization of the reappearance regime. Validation comes from a full microscopic theory.Our quantum system is a single self-assembled quantum dot (QD), an emitter of highly coherent single photons [2,3] and polarization-entangled photon pairs [4,5]. Quantum control of the exciton, an electron-hole pair, proceeds on picosecond timescales well before spontaneous emission takes place (timescale ∼1 ns). Phonons lead to a deterioration of the exciton preparation fidelity for schemes using resonant excitation [1,[6][7][8][9][10]. In fact, the interaction with the phonons is sufficiently strong that an exciton state can be prepared by relying on it (phonon-mediated relaxation following excitation with a detuned pulse) [11][12][13][14][15]. In a Rabi experiment, phonons lead to a clear damping [6,7]. The specific dephasing mechanism was identified as a coupling to longitudinal acoustic (LA) phonons. For higher pulse areas, theory predicts that the electronic oscillations become so fast such that the phonons decouple and the Rabi oscillations recover, the reappearance phenomenon. The existence of a pulse area for which the coupling to the phonons is maximal is a consequence of the nonmonotonic electron-phonon coupling [1,16].For the pulses used so far experimentally (pulses of 1-10 ps duration), the reappearance regime for Rabi oscillations can only be entered at ex...

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“…2, this frequency depends on the QD size; it can be roughly identified as the frequency of phonons with a wave length of the order of the QD size. The nonmonotonic behavior of the damping can now be understood in terms of a resonance between the exciton dynamics characterized by the Rabi frequency Ω Rabi and the dynamics of the most strongly coupled phonons characterized by ω max [129,125,174]. If these two frequencies coincide, the damping will be strongest.…”

Section: Rabi Rotationsmentioning

confidence: 99%

The role of phonons for exciton and biexciton generation in an optically driven quantum dot

Reiter

Kuhn

Glässl

et al. 2014

J. Phys.: Condens. Matter

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Abstract. For many applications of semiconductor quantum dots in quantum technology a well controlled state preparation of the quantum dot states is mandatory. Since quantum dots are embedded in the semiconductor matrix, the interaction with phonons plays often a major role in the preparation process. In this review, we discuss the influence of phonons on three basically different optical excitation schemes which can be used for the preparation of exciton, biexciton, and superposition states: a resonant excitation leading to Rabi rotations in the excitonic system, an excitation with chirped pulses exploiting the effect of adiabatic rapid passage, and an off-resonant excitation giving rise to a phononassisted state preparation. We give an overview over experimental and theoretical results showing the role of the phonons and compare the performance of the schemes for state preparation.

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Energy transport and coherence properties of acoustic phonons generated by optical excitation of a quantum dot

Cited by 29 publications

References 55 publications

Influence of excited state decay and dephasing on phonon quantum state preparation

Influence of excited state decay and dephasing on phonon quantum state preparation

Demonstrating the decoupling regime of the electron-phonon interaction in a quantum dot using chirped optical excitation

The role of phonons for exciton and biexciton generation in an optically driven quantum dot

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