Quantum dot Rabi rotations beyond the weak exciton–phonon coupling regime

McCutcheon, Dara P. S.; Nazir, Ahsan

doi:10.1088/1367-2630/12/11/113042

Cited by 177 publications

(300 citation statements)

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“…Starting from a microscopic Hamiltonian describing the odorant (as an oscillator), receptor (as a donor-acceptor two-level system), and environment (as a collection of independent oscillators), we derive a polaron-representation master equation for the ET process. [48][49][50][51][52][53][54][55][56][57][58] From this we may extract the relevant ET rates, extending previous analyses to a broader set of parameters and looking in more detail at the assumptions required for the MJ rates to be valid; in fact, these rates arise naturally from our master equation in the semiclassical limit where the temperature is high compared to the energy scales of the environment. In general, we find that the dynamics of donor-acceptor (DA) populations predicted by our master equation can differ considerably from that given by the simpler MJ rates.…”

Section: Introductionmentioning

confidence: 99%

Dissipation enhanced vibrational sensing in an olfactory molecular switch

Chęcińska

Pollock

Heaney

et al. 2015

The Journal of Chemical Physics

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Motivated by a proposed olfactory mechanism based on a vibrationally-activated molecular switch, we study electron transport within a donor-acceptor pair that is coupled to a vibrational mode and embedded in a surrounding environment. We derive a polaron master equation with which we study the dynamics of both the electronic and vibrational degrees of freedom beyond previously employed semiclassical (MarcusJortner) rate analyses. We show: (i) that in the absence of explicit dissipation of the vibrational mode, the semiclassical approach is generally unable to capture the dynamics predicted by our master equation due to both its assumption of one-way (exponential) electron transfer from donor to acceptor and its neglect of the spectral details of the environment; (ii) that by additionally allowing strong dissipation to act on the odorant vibrational mode we can recover exponential electron transfer, though typically at a rate that differs from that given by the Marcus-Jortner expression; (iii) that the ability of the molecular switch to discriminate between the presence and absence of the odorant, and its sensitivity to the odorant vibrational frequency, are enhanced significantly in this strong dissipation regime, when compared to the case without mode dissipation; and (iv) that details of the environment absent from previous Marcus-Jortner analyses can also dramatically alter the sensitivity of the molecular switch, in particular allowing its frequency resolution to be improved. Our results thus demonstrate the constructive role dissipation can play in facilitating sensitive and selective operation in molecular switch devices, as well as the inadequacy of semiclassical rate equations in analysing such behaviour over a wide range of parameters.

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Section: Introductionmentioning

confidence: 99%

Dissipation enhanced vibrational sensing in an olfactory molecular switch

Chęcińska

Pollock

Heaney

et al. 2015

The Journal of Chemical Physics

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“…Most often, these methods fully account for the dotlight coupling but treat the exciton-phonon interaction within further approximations. Examples of such approaches are the time-convolutionless approach [116,120,121], the correlation expansion [122,123,124,125,126], different types of master equations [116,53,64,127,88,128,93] or time-dependent perturbation theory [129,125]. For the Hamiltonian dynamics within the model established by Eqs.…”

Section: Theoretical Methodsmentioning

confidence: 99%

“…For QDs with a harmonic confinement potential in which the carriers are coupled to LA phonons via the deformation potential the phonon spectral density is well approximated by [63,64]: with a strength A and a cut-off frequency ω c determined by the size of the QD. For a spherical QD with equal confinement lengths a for electrons and holes this formula is exact and the parameters are given by…”

Section: Quantum Dot Modelmentioning

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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“…This allows the dominant non-perturbative non-Markovian phonon influence to be included, and permits us to derive analytic expressions in relevant regimes which elucidate the interplay between the Purcell and Franck-Condon factors, and trade-offs between efficiency and indistinguishability. Full details of the polaron transformation are given in the Supplementary information, though the central idea is to apply a displacement to the phonon mode operators dependent on the QD state, b k → b k − |X X| g k /ν k , as this removes the original exciton-phonon coupling from the Hamiltonian 23,38,[42][43][44] . Unitarity of the mode displacement means that the QD states must transform as |0 → |0 and |X → B + |X with…”

Section: Phonon Interactions In Optically Active Qdsmentioning

confidence: 99%

Imaginary echoes

Horiuchi¹

2017

Nature Photon

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Semiconductor quantum dots have recently emerged as a leading platform to efficiently generate highly indistinguishable photons, and this work addresses the timely question of how good these solid-state sources can ultimately be. We establish the crucial role of lattice relaxation in these systems in giving rise to trade-offs between indistinguishability and efficiency. We analyse the two source architectures most commonly employed: a quantum dot embedded in a waveguide and a quantum dot coupled to an optical cavity. For waveguides, we demonstrate that the broadband Purcell effect results in a simple inverse relationship, where indistinguishability and efficiency cannot be simultaneously increased. For cavities, the frequency selectivity of the Purcell enhancement results in a more subtle trade-off, where indistinguishability and efficiency can be simultaneously increased, though by the same mechanism not arbitrarily, limiting a source with near-unity indistinguishability (> 99%) to an efficiency of approximately 96% for realistic parameters.The efficient generation of on-demand highly indistinguishable photons remains a barrier to the scalability of a number of photonic quantum technologies 1-4 . To this end, attention has recently turned towards solid-state systems, and in particular semiconductor quantum dots (QDs) 5-13 , which can not only emit a single photon with high quantum efficiency, but can be easily integrated into larger photonic structures 14 , resulting in photons being emitted into a well-defined mode and direction. Highly directional emission is crucial to the overall efficiency of the source, and is typically achieved by either placing the QD in a waveguide with low out-of-plane scattering 15,16 , or by coupling resonantly to an optical cavity mode 6-9,12,13 . Nevertheless, the solid-state nature of QDs leads to strong coupling between the electronic degrees of freedom and their local environment; fluctuating charges 17 , nuclear spins 18,19 , and lattice vibrations 20-23 all lead to a suppression of photon coherence and a resulting reduction in indistinguishability 11,[24][25][26][27] . While early experiments were indeed limited by these factors 6-9 , improvements in fabrication and resonant excitation techniques have steadily increased photon indistinguishability to levels now exceeding 99% in resonantly coupled QD-cavity systems 12,13 . Photon extraction efficiencies have also steady improved, with the highest values reaching 98% in a photonic crystal waveguide 16 .Despite this impressive progress, a system boasting very high (> 99%) indistinguishability and efficiency as required for e.g. cluster state quantum computing 28 remains elusive. Strategies aimed at achieving such a source typically focus on engineering the photonic environment in order to maximise the Purcell effect 29,30 , where the QD emission rate becomes F P Γ, with Γ the bulk emission rate and F P the Purcell factor 29 . Modelling a QD as a simple two-level-system with a Markovian phenomenological dephasing rate γ, the Purc...

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Quantum dot Rabi rotations beyond the weak exciton–phonon coupling regime

Cited by 177 publications

References 64 publications

Dissipation enhanced vibrational sensing in an olfactory molecular switch

Dissipation enhanced vibrational sensing in an olfactory molecular switch

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

Imaginary echoes

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