https://ria.asturias.es/RIA/handle/123456789/6461 2025-12-18T11:54:15Z 2025-12-18T11:54:15Z Yuan, Xueyong Weyhausen-Brinkmann, Fritz Martín-Sánchez, Javier Piredda, Giovanni Krapek, Vlastimil Huo, Yongheng Huang, Huiying Schimpf, Christian Schmidt, Oliver G. Edlinger, Johannes Bester, Gabriel Trotta, Rinaldo Rastelli, Armando https://ria.asturias.es/RIA/handle/123456789/12626 2020-04-16T14:33:46Z 2018-08-03T00:00:00Z

Title: Uniaxial stress flips the quantization axis of a quantum dot for integrated quantum photonics Authors: Yuan, Xueyong; Weyhausen-Brinkmann, Fritz; Martín-Sánchez, Javier; Piredda, Giovanni; Krapek, Vlastimil; Huo, Yongheng; Huang, Huiying; Schimpf, Christian; Schmidt, Oliver G.; Edlinger, Johannes; Bester, Gabriel; Trotta, Rinaldo; Rastelli, Armando Abstract: The selection rules of optical transitions in epitaxial quantum dots are determined to a large extent by the orientation of their quantization axis, which is usually parallel to the growth direction. This configuration is well suited for single-photon sources embedded in vertically emitting devices, but not ideal for planar photonic circuits because of the poorly controlled orientation of the transition dipoles in the growth plane. Here we show that, for relatively large and initially unstrained GaAs dots, the quantization axis can be flipped to lie in the growth plane via moderate in-plane uniaxial stress. By using piezoelectric strain-actuators featuring strainamplification we study the evolution of the selection rules and excitonic fine-structure in a previously unexplored regime, in which quantum confinement can be seen as a perturbation compared to strain in determining the symmetry-properties of the system. The experimental and computational results suggest that uniaxial stress – already employed for enhancing the performance of integrated electronic circuits – may be the right strategy to obtain quantum-light sources with ideally oriented transition dipoles and enhanced oscillator strengths for integrated quantum photonic circuits.

2018-08-03T00:00:00Z Iff, Oliver Tedeschi, Davide Martín-Sánchez, Javier Moczala-Dusanowska, Magdalena Tongay, Sefaatin Yumigeta, Kentaro Taboada-Gutiérrez, Javier Saravesi, Matteo Rastelli, Armando Alonso-González, Pablo Höfling, Sven Trotta, Rinaldo Schneider, Christian https://ria.asturias.es/RIA/handle/123456789/12631 2020-04-16T14:33:07Z 2019-09-05T00:00:00Z

Title: Strain-tunable Single Photon Sources in WSe2 Monolayers Authors: Iff, Oliver; Tedeschi, Davide; Martín-Sánchez, Javier; Moczala-Dusanowska, Magdalena; Tongay, Sefaatin; Yumigeta, Kentaro; Taboada-Gutiérrez, Javier; Saravesi, Matteo; Rastelli, Armando; Alonso-González, Pablo; Höfling, Sven; Trotta, Rinaldo; Schneider, Christian Abstract: The appearance of single photon sources in atomically thin semiconductors holds great promises for the development of a flexible and ultra-compact quantum technology, in which elastic strain engineering can be used to tailor their emission properties. Here, we show a compact and hybrid 2D-semiconductorpiezoelectric device that allows for controlling the energy of single photons emitted by quantum emitters localized in wrinkled WSe2 monolayers. We demonstrate that strain fields exerted by the piezoelectric device can be used to tune the energy of localized excitons in WSe2 up to 18 meV in a reversible manner, while leaving the single photon purity unaffected over a wide range. Interestingly, we find that the magnitude and in particular the sign of the energy shift as a function of stress is emitter dependent. With the help of finite element simulations we suggest a simple model that explains our experimental observations and, furthermore, discloses that the type of strain (tensile or compressive) experienced by the quantum emitters strongly depends on their localization across the wrinkles. Our findings are of strong relevance for the practical implementation of single photon devices based on two-dimensional materials as well as for understanding the effects of strain on their emission properties.

2019-09-05T00:00:00Z Huber, Daniel Reindl, Marcus Filipe Covre da Silva, Saimon Schimpf, Christian Martín-Sánchez, Javier Huang, Huiying Piredda, Giovanni Edlinger, Johannes Rastelli, Armando Trotta, Rinaldo https://ria.asturias.es/RIA/handle/123456789/12625 2020-04-16T14:31:19Z 2018-07-18T00:00:00Z

Title: Strain-Tunable GaAs Quantum dot - A Nearly Dephasing-Free Source of Entangled Photon Pairs on Demand Authors: Huber, Daniel; Reindl, Marcus; Filipe Covre da Silva, Saimon; Schimpf, Christian; Martín-Sánchez, Javier; Huang, Huiying; Piredda, Giovanni; Edlinger, Johannes; Rastelli, Armando; Trotta, Rinaldo Abstract: We report on the observation of nearly maximally-entangled photon pairs from semiconductor quantum dots, without resorting to post-selection techniques. We use GaAs quantum dots integrated on a patterned piezoelectric actuator capable of suppressing the exciton fine structure splitting. By using a resonant two-photon excitation we coherently drive the biexciton state and demonstrate experimentally that our device generates polarization-entangled photons with a fidelity of 0.978(5) and a concurrence of 0.97(1) taking into account the nonidealities stemming from the experimental setup. By combining fine-structure-dependent fidelity measurements and a theoretical model, we identify an exciton spin-scattering process as a possible residual decoherence mechanism. We suggest that this imperfection may be overcome using a modest Purcell enhancement so as to achieve fidelities >0.99, thus making quantum dots evenly matched with the best probabilistic entangled photon sources.

2018-07-18T00:00:00Z Vizán García, Jesús Manuel CMS Collaboration https://ria.asturias.es/RIA/handle/123456789/7626 2018-04-18T07:57:43Z 2016-08-06T00:00:00Z

Title: Search for new physics in same-sign dilepton events in proton-proton collisions at sqrt(s) = 13 TeV Authors: Vizán García, Jesús Manuel; CMS Collaboration Abstract: A search for new physics is performed using events with two isolated same-sign leptons, two or more jets, and missing transverse momentum. The results are based on a sample of proton–proton collisions at a center-of-mass energy of 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 fb1. Multiple search regions are defined by classifying events in terms of missing transverse momentum, the scalar sum of jet transverse momenta, the transverse mass associated with a W boson candidate, the number of jets, the number of b quark jets, and the transverse momenta of the leptons in the event. The analysis is sensitive to a wide variety of possible signals beyond the standard model. No excess above the standard model background expectation is observed. Constraints are set on various supersymmetric models, with gluinos and bottom squarks excluded for masses up to 1300 and 680 GeV, respectively, at the 95 % confidence level. Upper limits on the cross sections for the production of two top quark-antiquark pairs (119 fb) and two same-sign top quarks (1.7 pb) are also obtained. Selection efficiencies and model independent limits are provided to allow further interpretations of the results.

2016-08-06T00:00:00Z