TY  - JOUR
A1  - Kreinberg, Sören
A1  - Grbešić, Tomislav
A1  - Strauß, Max
A1  - Carmele, Alexander
A1  - Emmerling, Monika
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Porte, Xavier
A1  - Reitzenstein, Stephan
T1  - Quantum-optical spectroscopy of a two-level system using an electrically driven micropillar laser as a resonant excitation source
JF  - Light: Science & Applications
N2  - Two-level emitters are the main building blocks of photonic quantum technologies and are model systems for the exploration of quantum optics in the solid state. Most interesting is the strict resonant excitation of such emitters to control their occupation coherently and to generate close to ideal quantum light, which is of utmost importance for applications in photonic quantum technology. To date, the approaches and experiments in this field have been performed exclusively using bulky lasers, which hinders the application of resonantly driven two-level emitters in compact photonic quantum systems. Here we address this issue and present a concept for a compact resonantly driven single-photon source by performing quantum-optical spectroscopy of a two-level system using a compact high-β microlaser as the excitation source. The two-level system is based on a semiconductor quantum dot (QD), which is excited resonantly by a fiber-coupled electrically driven micropillar laser. We dress the excitonic state of the QD under continuous wave excitation, and trigger the emission of single photons with strong multi-photon suppression (g\(^{(2)}\)(0)=0.02) and high photon indistinguishability (V = 57±9%) via pulsed resonant excitation at 156 MHz. These results clearly demonstrate the high potential of our resonant excitation scheme, which can pave the way for compact electrically driven quantum light sources with excellent quantum properties to enable the implementation of advanced quantum communication protocols.
KW  - near-infrared spectroscopy
KW  - photonic devices
KW  - semiconductor lasers
KW  - single photons and quantum effects
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229802
VL  - 7
ER  - 
TY  - JOUR
A1  - Waldherr, Max
A1  - Lundt, Nils
A1  - Klaas, Martin
A1  - Betzold, Simon
A1  - Wurdack, Matthias
A1  - Baumann, Vasilij
A1  - Estrecho, Eliezer
A1  - Nalitov, Anton
A1  - Cherotchenko, Evgenia
A1  - Cai, Hui
A1  - Ostrovskaya, Elena A.
A1  - Kavokin, Alexey V.
A1  - Tongay, Sefaattin
A1  - Klembt, Sebastian
A1  - Höfling, Sven
A1  - Schneider, Christian
T1  - Observation of bosonic condensation in a hybrid monolayer MoSe2-GaAs microcavity
JF  - Nature Communications
N2  - Bosonic condensation belongs to the most intriguing phenomena in physics, and was mostly reserved for experiments with ultra-cold quantum gases. More recently, it became accessible in exciton-based solid-state systems at elevated temperatures. Here, we demonstrate bosonic condensation driven by excitons hosted in an atomically thin layer of MoSe2, strongly coupled to light in a solid-state resonator. The structure is operated in the regime of collective strong coupling between a Tamm-plasmon resonance, GaAs quantum well excitons, and two-dimensional excitons confined in the monolayer crystal. Polariton condensation in a monolayer crystal manifests by a superlinear increase of emission intensity from the hybrid polariton mode, its density-dependent blueshift, and a dramatic collapse of the emission linewidth, a hallmark of temporal coherence. Importantly, we observe a significant spin-polarization in the injected polariton condensate, a fingerprint for spin-valley locking in monolayer excitons. Our results pave the way towards highly nonlinear, coherent valleytronic devices and light sources.
KW  - polaritons
KW  - two-dimensional materials
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-233280
VL  - 9
ER  - 
TY  - JOUR
A1  - Schneider, Christian
A1  - Glazov, Mikhail M.
A1  - Korn, Tobias
A1  - Höfling, Sven
A1  - Urbaszek, Bernhard
T1  - Two-dimensional semiconductors in the regime of strong light-matter coupling
JF  - Nature Communications
N2  - The optical properties of transition metal dichalcogenide monolayers are widely dominated by excitons, Coulomb-bound electron–hole pairs. These quasi-particles exhibit giant oscillator strength and give rise to narrow-band, well-pronounced optical transitions, which can be brought into resonance with electromagnetic fields in microcavities and plasmonic nanostructures. Due to the atomic thinness and robustness of the monolayers, their integration in van der Waals heterostructures provides unique opportunities for engineering strong light-matter coupling. We review first results in this emerging field and outline future opportunities and challenges.
KW  - optical physics
KW  - two-dimensional materials
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231295
VL  - 9
ER  - 
TY  - JOUR
A1  - Kreinberg, Sören
A1  - Porte, Xavier
A1  - Schicke, David
A1  - Lingnau, Benjamin
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Kanter, Ido
A1  - Lüdge, Kathy
A1  - Reitzenstein, Stephan
T1  - Mutual coupling and synchronization of optically coupled quantum-dot micropillar lasers at ultra-low light levels
JF  - Nature Communications
N2  - Synchronization of coupled oscillators at the transition between classical physics and quantum physics has become an emerging research topic at the crossroads of nonlinear dynamics and nanophotonics. We study this unexplored field by using quantum dot microlasers as optical oscillators. Operating in the regime of cavity quantum electrodynamics (cQED) with an intracavity photon number on the order of 10 and output powers in the 100 nW range, these devices have high β-factors associated with enhanced spontaneous emission noise. We identify synchronization of mutually coupled microlasers via frequency locking associated with a sub-gigahertz locking range. A theoretical analysis of the coupling behavior reveals striking differences from optical synchronization in the classical domain with negligible spontaneous emission noise. Beyond that, additional self-feedback leads to zero-lag synchronization of coupled microlasers at ultra-low light levels. Our work has high potential to pave the way for future experiments in the quantum regime of synchronization.
KW  - nanoscale devices
KW  - quantum optics
KW  - semiconductor lasers
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229811
VL  - 10
ER  - 
TY  - JOUR
A1  - Holzinger, Steffen
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Porte, Xavier
A1  - Reitzenstein, Stephan
T1  - Quantum-dot micropillar lasers subject to coherent time-delayed optical feedback from a short external cavity
JF  - Scientific Reports
N2  - We investigate the mode-switching dynamics of an electrically driven bimodal quantum-dot micropillar laser when subject to delayed coherent optical feedback from a short external cavity. We experimentally characterize how the external cavity length, being on the same order than the microlaser’s coherence length, influences the spectral and dynamical properties of the micropillar laser. Moreover, we determine the relaxation oscillation frequency of the micropillar by superimposing optical pulse injection to a dc current. It is found that the optical pulse can be used to disturb the feedback-coupled laser within one roundtrip time in such a way that it reaches the same output power as if no feedback was present. Our results do not only expand the understanding of microlasers when subject to optical feedback from short external cavities, but pave the way towards tailoring the properties of this key nanophotonic system for studies in the quantum regime of self-feedback and its implementation to integrated photonic circuits.
KW  - nanophotonics and plasmonics
KW  - photonic devices
KW  - quantum dots
KW  - semiconductor lasers
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322485
VL  - 9
ER  - 
TY  - JOUR
A1  - Li, Donghai
A1  - Shan, Hangyong
A1  - Rupprecht, Christoph
A1  - Knopf, Heiko
A1  - Watanabe, Kenji
A1  - Taniguchi, Takashi
A1  - Qin, Ying
A1  - Tongay, Sefaattin
A1  - Nuß, Matthias
A1  - Schröder, Sven
A1  - Eilenberger, Falk
A1  - Höfling, Sven
A1  - Schneider, Christian
A1  - Brixner, Tobias
T1  - Hybridized exciton-photon-phonon states in a transition-metal-dichalcogenide van-der-Waals heterostructure microcavity
JF  - Physical Review Letters
N2  - Excitons in atomically thin transition-metal dichalcogenides (TMDs) have been established as an attractive platform to explore polaritonic physics, owing to their enormous binding energies and giant oscillator strength. Basic spectral features of exciton polaritons in TMD microcavities, thus far, were conventionally explained via two-coupled-oscillator models. This ignores, however, the impact of phonons on the polariton energy structure. Here we establish and quantify the threefold coupling between excitons, cavity photons, and phonons. For this purpose, we employ energy-momentum-resolved photoluminescence and spatially resolved coherent two-dimensional spectroscopy to investigate the spectral properties of a high-quality-factor microcavity with an embedded WSe\(_2\) van-der-Waals heterostructure at room temperature. Our approach reveals a rich multi-branch structure which thus far has not been captured in previous experiments. Simulation of the data reveals hybridized exciton-photon-phonon states, providing new physical insight into the exciton polariton system based on layered TMDs.
KW  - strong coupling
KW  - laser spectroscopy
KW  - transition metal dichalcogenide
KW  - coherent multidimensional spectroscopy
KW  - exciton
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-351303
UR  - https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.087401
SN  - 1079-7114
ET  - accepted version
ER  - 
TY  - JOUR
A1  - Schlottmann, Elisabeth
A1  - Schicke, David
A1  - Krüger, Felix
A1  - Lingnau, Benjamin
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Lüdge, Kathy
A1  - Porte, Xavier
A1  - Reitzenstein, Stephan
T1  - Stochastic polarization switching induced by optical injection in bimodal quantum-dot micropillar lasers
JF  - Optics Express
N2  - Mutual coupling and injection locking of semiconductor lasers is of great interest in non-linear dynamics and its applications for instance in secure data communication and photonic reservoir computing. Despite its importance, it has hardly been studied in microlasers operating at mu W light levels. In this context, vertically emitting quantum dot micropillar lasers are of high interest. Usually, their light emission is bimodal, and the gain competition of the associated linearly polarized fundamental emission modes results in complex switching dynamics. We report on selective optical injection into either one of the two fundamental mode components of a bimodal micropillar laser. Both modes can lock to the master laser and influence the non-injected mode by reducing the available gain. We demonstrate that the switching dynamics can be tailored externally via optical injection in very good agreement with our theory based on semi-classical rate equations. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
KW  - Nonlinear Dynamics
KW  - Bistability
KW  - Generation
KW  - Subject
KW  - Regimes
KW  - Physics
KW  - Vcsels
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228603
VL  - 27
IS  - 20
ER  - 
TY  - JOUR
A1  - Lundt, Nils
A1  - Klembt, Sebastian
A1  - Cherotchenko, Evgeniia
A1  - Betzold, Simon
A1  - Iff, Oliver
A1  - Nalitov, Anton V.
A1  - Klaas, Martin
A1  - Dietrich, Christof P.
A1  - Kavokin, Alexey V.
A1  - Höfling, Sven
A1  - Schneider, Christian
T1  - Room-temperature Tamm-plasmon exciton-polaritons with a WSe\(_{2}\) monolayer
JF  - Nature Communications
N2  - Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light–matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe\(_{2}\), hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy–momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons.
KW  - optics and photonics
KW  - two-dimensional materials
KW  - electronic properties and materials
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169470
VL  - 7
ER  - 
TY  - JOUR
A1  - He, Yu-Ming
A1  - Iff, Oliver
A1  - Lundt, Nils
A1  - Baumann, Vasilij
A1  - Davanco, Marcelo
A1  - Srinivasan, Kartik
A1  - Höfling, Sven
A1  - Schneider, Christian
T1  - Cascaded emission of single photons from the biexciton in monolayered WSe\(_{2}\)
JF  - Nature Communications
N2  - Monolayers of transition metal dichalcogenide materials emerged as a new material class to study excitonic effects in solid state, as they benefit from enormous Coulomb correlations between electrons and holes. Especially in WSe\(_{2}\), sharp emission features have been observed at cryogenic temperatures, which act as single photon sources. Tight exciton localization has been assumed to induce an anharmonic excitation spectrum; however, the evidence of the hypothesis, namely the demonstration of a localized biexciton, is elusive. Here we unambiguously demonstrate the existence of a localized biexciton in a monolayer of WSe\(_{2}\), which triggers an emission cascade of single photons. The biexciton is identified by its time-resolved photoluminescence, superlinearity and distinct polarization in micro-photoluminescence experiments. We evidence the cascaded nature of the emission process in a cross-correlation experiment, which yields a strong bunching behaviour. Our work paves the way to a new generation of quantum optics experiments with two-dimensional semiconductors.
KW  - lasers
KW  - LED
KW  - quantum dots
KW  - light sources
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169363
VL  - 7
ER  - 
TY  - JOUR
A1  - Nitsche, Wolfgang H.
A1  - Kim, Na Young
A1  - Roumpos, Georgios
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Forchel, Alfred
A1  - Yamamoto, Yoshihisa
T1  - Spatial correlation of two-dimensional bosonic multimode condensates
JF  - Physical Review A
N2  - The Berezinskii-Kosterlitz-Thouless (BKT) theorem predicts that two-dimensional bosonic condensates exhibit quasi-long-range order which is characterized by a slow decay of the spatial coherence. However previous measurements on exciton-polariton condensates revealed that their spatial coherence can decay faster than allowed under the BKT theory, and different theoretical explanations have already been proposed. Through theoretical and experimental study of exciton-polariton condensates, we show that the fast decay of the coherence can be explained through the simultaneous presence of multiple modes in the condensate.
KW  - Exciton-polariton condensate
KW  - Long-range order
KW  - Microcavity
KW  - Vortices
KW  - Systems
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-188897
VL  - 93
IS  - 5
ER  -