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Physique de l'exciton, du photon et du spin
(78) Production(s) de l'année 2017
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Giant Interatomic Energy-Transport Amplification with Nonreciprocal Photonic Topological Insulators
Auteur(s): Doyeux P., Hassani Gangaraj S. Ali, Hanson George W., Antezza M.
(Article) Publié:
Physical Review Letters, vol. 119 p.173901 (2017)
Texte intégral en Openaccess :
Ref HAL: hal-01624891_v1
DOI: 10.1103/PhysRevLett.119.173901
WoS: 000413770200001
Exporter : BibTex | endNote
9 Citations
Résumé: We show that the energy-transport efficiency in a chain of two-level emitters can be drastically enhanced by the presence of a photonic topological insulator (PTI). This is obtained by exploiting the peculiar properties of its nonreciprocal surface plasmon polariton (SPP), which is unidirectional, and immune to backscattering, and propagates in the bulk band gap. This amplification of transport efficiency can be as much as 2 orders of magnitude with respect to reciprocal SPPs. Moreover, we demonstrate that despite the presence of considerable imperfections at the interface of the PTI, the efficiency of the SPP-assisted energy transport is almost unaffected by discontinuities. We also show that the SPP properties allow energy transport over considerably much larger distances than in the reciprocal case, and we point out aparticularly simple way to tune the transport. Finally, we analyze the specific case of a two-emitter chain and unveil the origin of the efficiency amplification. The efficiency amplification and the practical advantages highlighted in this work might be particularly useful in the development of new devices intended to manage energy at the atomic scale.
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Carrier spin relaxation in diluted magnetic quantum wells: Effect of Mn spin correlations
Auteur(s): Krainov I. V., Vladimirova M., Scalbert D., Lahderanta E., Dmitriev A. P., Averkiev N. S.
(Article) Publié:
Physical Review B, vol. 96 p.165304 (2017)
Ref HAL: hal-01621240_v1
DOI: 10.1103/PhysRevB.96.165304
WoS: WOS:000412747900006
Exporter : BibTex | endNote
1 Citation
Résumé: We demonstrate theoretically that the presence of holes, either resident or photocreated, in diluted magnetic quantum wells accelerates the spin relaxation of electrons via a mechanismwhich has been previously overlooked. This effect is due to the spin correlations, which establish between magnetic ions coupled via hole-mediated Ruderman-Kittel-Kasuya-Yoshida interactions in the paramagnetic phase. As a consequence, the electron spin relaxation becomes temperature and hole density dependent, in contrast to existing theories. Our theory qualitatively reproduces the increase of the electron spin relaxation rate with pump power observed in n-doped CdMnTe magnetic quantum wells [Ben Cheikh et al., Phys. Rev. B 88, 201306 (2013)]. It also predicts a decrease of the spin relaxation rate with temperature, as observed, although not in the same temperature range.
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Spin temperature concept verified by optical magnetometry of nuclear spins
Auteur(s): Scalbert D.
Conférence invité: 9th Russian-French Workshop on Nanosciences and Nanotechnologies (Suzdal, RU, 2017-10-04)
Ref HAL: hal-01619882_v1
Exporter : BibTex | endNote
Résumé: We develop a method of non-perturbative optical control over adiabatic remagnetisation of the nuclear spin system in semiconductors and apply it to study nuclear spin thermodynamics in GaAs microcavities. The nuclear spin system is found to exactly follow the predictions of the spin-temperature theory, despite the quadrupole interactionthat was earlier reported to disrupt nuclear spin thermalisation [2]. These findings open a way to deep cooling of nuclear spins in semiconductor structures, with a prospect of realisation of nuclear spin-ordered states for high fidelity spin-photon interfaces.References[1] A. S. Oja, O. V. Lounasmaa, Rev. Mod. Phys 69, 1 (1997).[2] P. Maletinsky, M. Kroner, A. Imamoglu, Nat. Phys 5, 407 (2009).
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Stimulated Raman adiabatic control of a nuclear spin in diamond
Auteur(s): Coto Raul, Jacques V., Hetet Gabriel, Maze Jeronimo R.
(Article) Publié:
Physical Review B, vol. 96 p.085420 (2017)
Texte intégral en Openaccess :
Ref HAL: hal-01588967_v1
DOI: 10.1103/PhysRevB.96.085420
WoS: WOS:000407549100007
Exporter : BibTex | endNote
5 Citations
Résumé: Coherent manipulation of nuclear spins is a highly desirable tool for both quantum metrology and quantum computation. However, most of the current techniques to control nuclear spins lack fast speed, impairing their robustness against decoherence. Here, based on stimulated Raman adiabatic passage, and its modification including shortcuts to adiabaticity, we present a fast protocol for the coherent manipulation of nuclear spins. Our proposed Λ scheme is implemented in the microwave domain and its excited-state relaxation can be optically controlled through an external laser excitation. These features allow for the initialization of a nuclear spin starting from a thermal state. Moreover we show how to implement Raman control for performing Ramsey spectroscopy to measure the dynamical and geometric phases acquired by nuclear spins.
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Influence of the heterostructure design on the optical properties of GaN and Al0.1Ga0.9N quantum dots for ultraviolet emission
Auteur(s): Matta S., Brault Julien, Ngo T. H., Damilano B., Korytov Maxim, Vennegues P, Nemoz Maud, Massies Jean, Leroux Mathieu, Gil B.
(Article) Publié:
Journal Of Applied Physics, vol. 122 p.085706 (2017)
Ref HAL: hal-01579358_v1
DOI: 10.1063/1.5000238
WoS: 000409117200061
Exporter : BibTex | endNote
9 Citations
Résumé: The optical properties of AlyGa1-yN quantum dots (QDs), with y 1⁄4 0 or y 1⁄4 0.1, in an AlxGa1 xN matrix are studied. The influence of the QD layer design is investigated pointing out the correlations between the QD structural and optical properties. In a first part, the role of the epitaxial strain in the dot self-assembling process is studied by fabricating GaN QD layers on different AlxGa1 xN layers with 0.5 x 0.7. Photoluminescence (PL) measurements show the main influ- ence of the increase of the internal electric field (Fint) on the QD optical response inducing a strong red shift in the emission energy as x increases. Time resolved combined with temperature depen- dent PL measurements enabled the estimation of the QD internal quantum efficiencies at low tem- perature showing values around 50%. In addition, a PL integrated intensity ratio up to 74% is shown, between 300 and 9 K. In the second part, the design of Al0.1Ga0.9N QDs was investigated, by varying the Al0.1Ga0.9N amount deposited. An increase of the transition energy (from 3.65 eV up to 3.83eV) is obtained while decreasing the deposited amount. Calculations of the ground state transition energies as a function of the Al0.1Ga0.9N dot height give a value of Fint around 2.060.5MV/cm. Therefore, the propensity of Al0.1Ga0.9N dots to emit at much higher energies than GaN dots (a PL shift of 1 eV using a low excitation power) is seen as the consequence of the reduced Fint together with their smaller sizes.
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Transition from spin-orbit to hyperfine interaction dominated spin relaxation in a cold fluid of dipolar excitons
Auteur(s): Finkelstein Ran, Cohen Kobi, Jouault B., West Ken, Pfeiffer Loren N., Vladimirova M., Rapaport Ronen
(Article) Publié:
Physical Review B, vol. 96 p.085404 (2017)
Texte intégral en Openaccess :
Ref HAL: hal-01577957_v2
DOI: 10.1103/PhysRevB.96.085404
WoS: WOS:000406752500006
Exporter : BibTex | endNote
3 Citations
Résumé: We measure the spin-resolved transport of dipolar excitons in a biased GaAs double quantum well structure. From these measurements we extract both spin lifetime and mobility of the excitons. We find that below a temperature of 4.8K there is a sharp increase in the spin lifetime of the excitons, together with a sharp reduction in their mobility. Below a critical power the spin lifetime increases with increasing mobility and density, while above the critical power the opposite trend is observed. We interpret this transition as evidence of the interplay between two different spin dephasing mechanisms: at low mobility the dephasing is dominated by the hyperfine interaction with the lattice nuclei spins, while at higher mobility the spin-orbit interaction dominates and a Dyakonov-Perel spin relaxation takes over. The excitation power and temperature regime where the hyperfine interaction induced spin dephasing is observed correlates with the regime where a dark dipolar quantum liquid was reported recently on a similar sample.
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Polarization Properties of Laser Solitons
Auteur(s): Rodriguez Pedro, Jimenez Jesus, Guillet T., Ackemann Thorsten
(Article) Publié:
Applied Sciences, vol. 7 p.442 (2017)
Texte intégral en Openaccess :
Ref HAL: hal-01576088_v1
DOI: 10.3390/app7050442
WoS: WOS:000404449000010
Exporter : BibTex | endNote
1 Citation
Résumé: The objective of this paper is to summarize the results obtained for the state of polarization in the emission of a vertical-cavity surface-emitting laser with frequency-selective feedback added. We start our research with the single soliton, this situation presents two perpendicular main orientations, connected by a hysteresis loop. In addition, we also find the formation of a ring shaped intensity distribution, the vortex state, that shows two homogeneous states of polarization with very close values to those find in the soliton. For both cases above, the study shows the spatially resolved value of the orientation angle. It's important to remark too the appearance of a non negligible amount of circular light that gives vectorial character to all the different emissions investigated.
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