Fluctuation properties of phonons generated by ultrafast optical excitation of a quantum dot

Reiter, Doris E.; Wigger, Daniel; Daniels, J. M.; Papenkort, Thomas; Vagov, Alexei; Axt, Vollrath M.; Kuhn, Thomas

doi:10.1002/pssb.201000783

Cited by 6 publications

(7 citation statements)

References 19 publications

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“…For the largest considered dephasing rate of β = 0.5 ω ph the incoherent limit of a statistical mixture of all four coherent states (dashed lines) is almost reached. The minimum of the momentum's EIF is S Π = 0 whereas the displacement's EIF remains always positive as is expected for the statistical mixture of four coherent states oscillating around equilibrium positions shifted in the U direction [32].…”

Section: B Two-pulse Excitationsupporting

confidence: 63%

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: B Two-pulse Excitationsupporting

confidence: 63%

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

et al. 2019

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“…In the case of a phase difference φ = 0 as taken in Fig. 3 the expectation value then evaluates to û(r, t) φ=0 ≃ u 0 [2P (r) + W (r, t + τ ) + W (r, t)], (13) where P (r) and W (r, t) are defined in Eqs. ( 8) and ( 9).…”

Section: B Two Pulse Excitationmentioning

confidence: 99%

“…2,3 Phonons are another type of bosons where nonclassical states have become of growing interest in the past years. Squeezed phonons have been the subject of many experimental [4][5][6][7][8] and theoretical [9][10][11][12][13][14][15] studies. In most cases the considered phonons had a fixed frequency, either because they were optical phonons [4][5][6][9][10][11][12][13][14] or a van Hove singularity appeared in the spectrum of acoustic phonons.…”

Section: Introductionmentioning

confidence: 99%

“…Squeezed phonons have been the subject of many experimental [4][5][6][7][8] and theoretical [9][10][11][12][13][14][15] studies. In most cases the considered phonons had a fixed frequency, either because they were optical phonons [4][5][6][9][10][11][12][13][14] or a van Hove singularity appeared in the spectrum of acoustic phonons. 7 An indication for squeezing is then the appearance of an oscillation with the double phonon frequency, however this alone is not yet an unambiguous proof for squeezing.…”

Section: Introductionmentioning

confidence: 99%

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Fluctuation properties of acoustic phonons generated by ultrafast optical excitation of a quantum dot

et al. 2013

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We study theoretically the fluctuation properties of acoustic phonons created in a semiconductor quantum dot after ultrafast optical excitation. An excitation with a single ultrafast pulse creates an exciton confined to the quantum dot, which is coupled to longitudinal acoustic phonons. This leads to the formation of a polaron in the quantum dot accompanied by the emission of a phonon wave packet. We show that the fluctuations of the lattice displacement associated with the wave packet after a single laser pulse excitation in resonance with the exciton transition are always larger than their respective vacuum values. Manipulating the exciton with a second pulse can result in a reduction of the fluctuations below their vacuum limit, which means that the phonons are squeezed. We show that the squeezing properties of the wave packet strongly depend on the relative phase and the time delay between the two laser pulses.

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“…The correlation expansion has been shown to compare well with the numerically exact path integral formalism [63]. An advantage of the correlation expansion is that the phonon dynamics is explicitly taken into account, such that also phonon properties like fluctuation dynamics can directly be extracted from the calculations [64,65]. To evaluate the influence of phonons on the preparation schemes, we also analyze the corresponding phonon dynamics.…”

Section: Electron-phonon Interactionmentioning

confidence: 99%

Phonon wave packet emission during state preparation of a semiconductor quantum dot using different schemes

Bracht,

Seidelmann,

Kuhn

et al. 2022

Preprint

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The carrier-phonon interaction in semiconductor quantum dots can greatly affect the optical preparation of the excited state. For resonant excitation used in the Rabi preparation scheme, the polaron is formed accompanied by the emission of a phonon wave packet, leading to a degradation of preparation fidelity. In this paper, phonon wave packets for different coherent excitation schemes are analyzed. One example is the adiabatic rapid passage scheme relying on a chirped excitation. Here, also a phonon wave packet is emitted, but the preparation fidelity can still be approximately unity. A focus is on the phonon impact on a recently proposed swing-up scheme, induced by two detuned pulses. Similar to the Rabi scheme, a degradation and a phonon wave packet emission is found, despite the detuning. If the swing-up frequency coincides with the maximum of the phonon spectral density, a series of wave packets is emitted yielding an even stronger degradation. The insight gained from our results will further help in designing an optimal preparation scheme for quantum dots.

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Fluctuation properties of phonons generated by ultrafast optical excitation of a quantum dot

Cited by 6 publications

References 19 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

Fluctuation properties of acoustic phonons generated by ultrafast optical excitation of a quantum dot

Phonon wave packet emission during state preparation of a semiconductor quantum dot using different schemes

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