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  - Wyborski, Paweł
A1  - Podemski, Paweł
A1  - Wroński, Piotr Andrzej
A1  - Jabeen, Fauzia
A1  - Höfling, Sven
A1  - Sęk, Grzegorz
T1  - Electronic and optical properties of InAs QDs grown by MBE on InGaAs metamorphic buffer
JF  - Materials
N2  - We present the optical characterization of GaAs-based InAs quantum dots (QDs) grown by molecular beam epitaxy on a digitally alloyed InGaAs metamorphic buffer layer (MBL) with gradual composition ensuring a redshift of the QD emission up to the second telecom window. Based on the photoluminescence (PL) measurements and numerical calculations, we analyzed the factors influencing the energies of optical transitions in QDs, among which the QD height seems to be dominating. In addition, polarization anisotropy of the QD emission was observed, which is a fingerprint of significant valence states mixing enhanced by the QD confinement potential asymmetry, driven by the decreased strain with increasing In content in the MBL. The barrier-related transitions were probed by photoreflectance, which combined with photoluminescence data and the PL temperature dependence, allowed for the determination of the carrier activation energies and the main channels of carrier loss, identified as the carrier escape to the MBL barrier. Eventually, the zero-dimensional character of the emission was confirmed by detecting the photoluminescence from single QDs with identified features of the confined neutral exciton and biexciton complexes via the excitation power and polarization dependences.
KW  - molecular beam epitaxy
KW  - quantum dot
KW  - metamorphic buffer layer
KW  - band structure
KW  - photoluminescence
KW  - photoreflectance
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-297037
SN  - 1996-1944
VL  - 15
IS  - 3
ER  - 
TY  - JOUR
A1  - Pfenning, Andreas
A1  - Krüger, Sebastian
A1  - Jabeen, Fauzia
A1  - Worschech, Lukas
A1  - Hartmann, Fabian
A1  - Höfling, Sven
T1  - Single-photon counting with semiconductor resonant tunneling devices
JF  - Nanomaterials
N2  - Optical quantum information science and technologies require the capability to generate, control, and detect single or multiple quanta of light. The need to detect individual photons has motivated the development of a variety of novel and refined single-photon detectors (SPDs) with enhanced detector performance. Superconducting nanowire single-photon detectors (SNSPDs) and single-photon avalanche diodes (SPADs) are the top-performer in this field, but alternative promising and innovative devices are emerging. In this review article, we discuss the current state-of-the-art of one such alternative device capable of single-photon counting: the resonant tunneling diode (RTD) single-photon detector. Due to their peculiar photodetection mechanism and current-voltage characteristic with a region of negative differential conductance, RTD single-photon detectors provide, theoretically, several advantages over conventional SPDs, such as an inherently deadtime-free photon-number resolution at elevated temperatures, while offering low dark counts, a low timing jitter, and multiple photon detection modes. This review article brings together our previous studies and current experimental results. We focus on the current limitations of RTD-SPDs and provide detailed design and parameter variations to be potentially employed in next-generation RTD-SPD to improve the figure of merits of these alternative single-photon counting devices. The single-photon detection capability of RTDs without quantum dots is shown.
KW  - single-photon detectors
KW  - resonant tunneling diode
KW  - photon counting
KW  - III–V semiconductor devices
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-281922
SN  - 2079-4991
VL  - 12
IS  - 14
ER  - 
TY  - JOUR
A1  - Rothmayr, Florian
A1  - Guarin Castro, Edgar David
A1  - Hartmann, Fabian
A1  - Knebl, Georg
A1  - Schade, Anne
A1  - Höfling, Sven
A1  - Koeth, Johannes
A1  - Pfenning, Andreas
A1  - Worschech, Lukas
A1  - Lopez-Richard, Victor
T1  - Resonant tunneling diodes: mid-infrared sensing at room temperature
JF  - Nanomaterials
N2  - Resonant tunneling diode photodetectors appear to be promising architectures with a simple design for mid-infrared sensing operations at room temperature. We fabricated resonant tunneling devices with GaInAsSb absorbers that allow operation in the 2–4 μm range with significant electrical responsivity of 0.97 A/W at 2004 nm to optical readout. This paper characterizes the photosensor response contrasting different operational regimes and offering a comprehensive theoretical analysis of the main physical ingredients that rule the sensor functionalities and affect its performance. We demonstrate how the drift, accumulation, and escape efficiencies of photogenerated carriers influence the electrostatic modulation of the sensor's electrical response and how they allow controlling the device's sensing abilities.
KW  - resonant tunneling diode
KW  - mid-infrared sensing
KW  - photosensor
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-267152
SN  - 2079-4991
VL  - 12
IS  - 6
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  - Wyborski, Paweł
A1  - Musiał, Anna
A1  - Mrowiński, Paweł
A1  - Podemski, Paweł
A1  - Baumann, Vasilij
A1  - Wroński, Piotr
A1  - Jabeen, Fauzia
A1  - Höfling, Sven
A1  - Sęk, Grzegorz
T1  - InP-substrate-based quantum dashes on a DBR as single-photon emitters at the third telecommunication window
JF  - Materials
N2  - We investigated emission properties of photonic structures with InAs/InGaAlAs/InP quantum dashes grown by molecular beam epitaxy on a distributed Bragg reflector. In high-spatial-resolution photoluminescence experiment, well-resolved sharp spectral lines are observed and single-photon emission is detected in the third telecommunication window characterized by very low multiphoton events probabilities. The photoluminescence spectra measured on simple photonic structures in the form of cylindrical mesas reveal significant intensity enhancement by a factor of 4 when compared to a planar sample. These results are supported by simulations of the electromagnetic field distribution, which show emission extraction efficiencies even above 18% for optimized designs. When combined with relatively simple and undemanding fabrication approach, it makes this kind of structures competitive with the existing solutions in that spectral range and prospective in the context of efficient and practical single-photon sources for fiber-based quantum networks applications.
KW  - single-photon emitter
KW  - III–V quantum dot
KW  - telecommunication spectral range
KW  - photonic structure
KW  - extraction efficiency
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228773
SN  - 1996-1944
VL  - 14
IS  - 4
ER  - 
TY  - JOUR
A1  - Wroński, Piotr Andrzej
A1  - Wyborski, Paweł
A1  - Musiał, Anna
A1  - Podemski, Paweł
A1  - Sęk, Grzegorz
A1  - Höfling, Sven
A1  - Jabeen, Fauzia
T1  - Metamorphic Buffer Layer Platform for 1550 nm Single-Photon Sources Grown by MBE on (100) GaAs Substrate
JF  - Materials
N2  - We demonstrate single-photon emission with a low probability of multiphoton events of 5% in the C-band of telecommunication spectral range of standard silica fibers from molecular beam epitaxy grown (100)-GaAs-based structure with InAs quantum dots (QDs) on a metamorphic buffer layer. For this purpose, we propose and implement graded In content digitally alloyed InGaAs metamorphic buffer layer with maximal In content of 42% and GaAs/AlAs distributed Bragg reflector underneath to enhance the extraction efficiency of QD emission. The fundamental limit of the emission rate for the investigated structures is 0.5 GHz based on an emission lifetime of 1.95 ns determined from time-resolved photoluminescence. We prove the relevance of a proposed technology platform for the realization of non-classical light sources in the context of fiber-based quantum communication applications.
KW  - single-photon source
KW  - quantum dots
KW  - telecommunication spectral range
KW  - metamorphic buffer layer
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-246145
SN  - 1996-1944
VL  - 14
IS  - 18
ER  - 
TY  - JOUR
A1  - van Loock, Peter
A1  - Alt, Wolfgang
A1  - Becher, Christoph
A1  - Benson, Oliver
A1  - Boche, Holger
A1  - Deppe, Christian
A1  - Eschner, Jürgen
A1  - Höfling, Sven
A1  - Meschede, Dieter
A1  - Michler, Peter
A1  - Schmidt, Frank
A1  - Weinfurter, Harald
T1  - Extending Quantum Links: Modules for Fiber‐ and Memory‐Based Quantum Repeaters
JF  - Advanced Quantum Technologies
N2  - Elementary building blocks for quantum repeaters based on fiber channels and memory stations are analyzed. Implementations are considered for three different physical platforms, for which suitable components are available: quantum dots, trapped atoms and ions, and color centers in diamond. The performances of basic quantum repeater links for these platforms are evaluated and compared, both for present‐day, state‐of‐the‐art experimental parameters as well as for parameters that can in principle be reached in the future. The ultimate goal is to experimentally explore regimes at intermediate distances—up to a few 100 km—in which the repeater‐assisted secret key transmission rates exceed the maximal rate achievable via direct transmission. Two different protocols are considered, one of which is better adapted to the higher source clock rate and lower memory coherence time of the quantum dot platform, while the other circumvents the need of writing photonic quantum states into the memories in a heralded, nondestructive fashion. The elementary building blocks and protocols can be connected in a modular form to construct a quantum repeater system that is potentially scalable to large distances.
KW  - color centers
KW  - quantum communication
KW  - quantum dots
KW  - quantum repeaters
KW  - trapped atoms/ions
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228322
VL  - 3
IS  - 11
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  -