TY  - JOUR
A1  - Kim, Seonghoon
A1  - Zhang, Bo
A1  - Wang, Zhaorong
A1  - Fischer, Julian
A1  - Brodbeck, Sebastian
A1  - Kamp, Martin
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Deng, Hui
T1  - Coherent Polariton Laser
JF  - Physical Review X
N2  - The semiconductor polariton laser promises a new source of coherent light, which, compared to conventional semiconductor photon lasers, has input-energy threshold orders of magnitude lower. However, intensity stability, a defining feature of a coherent state, has remained poor. Intensity noise many times the shot noise of a coherent state has persisted, attributed to multiple mechanisms that are difficult to separate in conventional polariton systems. The large intensity noise, in turn, limits the phase coherence. Thus, the capability of the polariton laser as a source of coherence light is limited. Here, we demonstrate a polariton laser with shot-noise-limited intensity stability, as expected from a fully coherent state. This stability is achieved by using an optical cavity with high mode selectivity to enforce single-mode lasing, suppress condensate depletion, and establish gain saturation. Moreover, the absence of spurious intensity fluctuations enables the measurement of a transition from exponential to Gaussian decay of the phase coherence of the polariton laser. It suggests large self-interaction energies in the polariton condensate, exceeding the laser bandwidth. Such strong interactions are unique to matter-wave lasers and important for nonlinear polariton devices. The results will guide future development of polariton lasers and nonlinear polariton devices.
KW  - polariton laser
KW  - condensed matter physics
KW  - photonics
KW  - quantum physics
KW  - coherent light
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166597
VL  - 6
IS  - 011026
ER  - 
TY  - JOUR
A1  - Redlich, Christoph
A1  - Lingnau, Benjamin
A1  - Holzinger, Steffen
A1  - Schlottmann, Elisabeth
A1  - Kreinberg, Sören
A1  - Schneider, Christian
A1  - Kamp, Martin
A1  - Höfling, Sven
A1  - Wolters, Janik
A1  - Reitzenstein, Stephan
A1  - Lüdge, Kathy
T1  - Mode-switching induced super-thermal bunching in quantum-dot microlasers
JF  - New Journal of Physics
N2  - The super-thermal photon bunching in quantum-dot (QD) micropillar lasers is investigated both experimentally and theoretically via simulations driven by dynamic considerations. Using stochastic multi-mode rate equations we obtain very good agreement between experiment and theory in terms of intensity profiles and intensity-correlation properties of the examined QD micro-laser's emission. Further investigations of the time-dependent emission show that super-thermal photon bunching occurs due to irregular mode-switching events in the bimodal lasers. Our bifurcation analysis reveals that these switchings find their origin in an underlying bistability, such that spontaneous emission noise is able to effectively perturb the two competing modes in a small parameter region. We thus ascribe the observed high photon correlation to dynamical multistabilities rather than quantum mechanical correlations.
KW  - microlaser
KW  - nonlinear dynamics
KW  - correlation properties
KW  - photon statistics
KW  - noise and multimode dynamics
KW  - quantum dot laser
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166286
VL  - 18
IS  - 063011
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  - 
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  - Amthor, Matthias
A1  - Weißenseel, Sebastian
A1  - Fischer, Julian
A1  - Kamp, Martin
A1  - Schneider, Christian
A1  - Höfling, Sven
T1  - Electro-optical switching between polariton and cavity lasing in an InGaAs quantum well microcavity
N2  - We report on the condensation of microcavity exciton polaritons under optical excitation in a microcavity with four embedded InGaAs quantum wells. The polariton laser is characterized by a distinct nonlinearity in the input-output-characteristics, which is accompanied by a drop of the emission linewidth indicating temporal coherence and a characteristic persisting emission blueshift with increased particle density. The temporal coherence of the device at threshold is underlined by a characteristic drop of the second order coherence function to a value close to 1. Furthermore an external electric field is used to switch between polariton regime, polariton condensate and photon lasing.
KW  - Quantum-well, -wire and -dot devices
KW  - Scattering
KW  - stimulated
KW  - Resonators
KW  - Microcavity devices
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-111130
ER  - 
TY  - JOUR
A1  - Winkler, Karol
A1  - Fischer, Julian
A1  - Schade, Anne
A1  - Amthor, Matthias
A1  - Dall, Robert
A1  - Geßler, Jonas
A1  - Emmerling, Monika
A1  - Ostrovskaya, Elena A.
A1  - Kamp, Martin
A1  - Schneider, Christian
A1  - Höfling, Sven
T1  - A polariton condensate in a photonic crystal potential landscape
JF  - New Journal of Physics
N2  - The possibility of investigating macroscopic coherent quantum states in polariton condensates and of engineering polariton landscapes in semiconductors has triggered interest in using polaritonic systems to simulate complex many-body phenomena. However, advanced experiments require superior trapping techniques that allow for the engineering of periodic and arbitrary potentials with strong on-site localization, clean condensate formation, and nearest-neighbor coupling. Here we establish a technology that meets these demands and enables strong, potentially tunable trapping without affecting the favorable polariton characteristics. The traps are based on a locally elongated microcavity which can be formed by standard lithography. We observe polariton condensation with non-resonant pumping in single traps and photonic crystal square lattice arrays. In the latter structures, we observe pronounced energy bands, complete band gaps, and spontaneous condensation at the M-point of the Brillouin zone.
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125050
VL  - 17
ER  - 
TY  - JOUR
A1  - Maier, Sebastian
A1  - Gold, Peter
A1  - Forchel, Alfred
A1  - Gregersen, Niels
A1  - Mork, Jesper
A1  - Höfling, Sven
A1  - Schneider, Christian
A1  - Kamp, Martin
T1  - Bright single photon source based on self-aligned quantum dot-cavity systems
JF  - Optics Express
N2  - We report on a quasi-planar quantum-dot-based single-photon source that shows an unprecedented high extraction efficiency of 42% without complex photonic resonator geometries or post-growth nanofabrication. This very high efficiency originates from the coupling of the photons emitted by a quantum dot to a Gaussian shaped nanohill defect that naturally arises during epitaxial growth in a self-aligned manner. We investigate the morphology of these defects and characterize the photonic operation mechanism. Our results show that these naturally arising coupled quantum dot-defects provide a new avenue for efficient (up to 42% demonstrated) and pure (g(2)(0) value of 0.023) single-photon emission.
KW  - photon statistics
KW  - quantum communications
KW  - resonators
KW  - quantum-well -wire and -dot devices
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119801
SN  - 1094-4087
VL  - 22
IS  - 7
ER  - 
TY  - JOUR
A1  - Motyka, Marcin
A1  - Sęk, Grzegorz
A1  - Ryczko, Krzysztof
A1  - Dyksik, Mateusz
A1  - Weih, Robert
A1  - Patriarche, Gilles
A1  - Misiewicz, Jan
A1  - Kamp, Martin
A1  - Höfling, Sven
T1  - Interface Intermixing in Type II InAs/GaInAsSb Quantum Wells Designed for Active Regions of Mid-Infrared-Emitting Interband Cascade Lasers
JF  - Nanoscale Research Letters
N2  - The effect of interface intermixing in W-design GaSb/AlSb/InAs/Ga\(_{0.665}\)In\(_{0.335}\)As\(_x\)Sb\(_{1-x}\)/InAs/AlSb/GaSb quantum wells (QWs) has been investigated by means of optical spectroscopy supported by structural data and by band structure calculations. The fundamental optical transition has been detected at room temperature through photoluminescence and photoreflectance measurements and appeared to be blueshifted with increasing As content of the GaInAsSb layer, in contrast to the energy-gap-driven shifts calculated for an ideally rectangular QW profile. The arsenic incorporation into the hole-confining layer affects the material and optical structure also altering the InAs/GaInAsSb interfaces and their degree of intermixing. Based on the analysis of cross-sectional transmission electron microscopy images and energy-dispersive X-ray spectroscopy, we could deduce the composition distribution across the QW layers and hence simulate more realistic confinement potential profiles. For such smoothed interfaces that indicate As-enhanced intermixing, the energy level calculations have been able to reproduce the experimentally obtained trend.
KW  - FTIR spectroscopy
KW  - type II GaIn(As)Sb/GaSb
KW  - QW interface profile
KW  - intermixing
KW  - interband cascade lasers
KW  - EDX spectra
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-136386
VL  - 10
IS  - 471
ER  - 
TY  - JOUR
A1  - Dyksik, Mateusz
A1  - Motyka, Marcin
A1  - Sęk, Grzegorz
A1  - Misiewicz, Jan
A1  - Dallner, Matthias
A1  - Weih, Robert
A1  - Kamp, Martin
A1  - Höfling, Sven
T1  - Submonolayer Uniformity of Type II InAs/GaInSb W-shaped Quantum Wells Probed by Full-Wafer Photoluminescence Mapping in the Mid-infrared Spectral Range
JF  - Nanoscale Research Letters
N2  - The spatial uniformity of GaSb- and InAs substrate-based structures containing type II quantum wells was probed by means of large-scale photoluminescence (PL) mapping realized utilizing a Fourier transform infrared spectrometer. The active region was designed and grown in a form of a W-shaped structure with InAs and GaInSb layers for confinement of electrons and holes, respectively. The PL spectra were recorded over the entire 2-in. wafers, and the parameters extracted from each spectrum, such as PL peak energy position, its linewidth and integrated intensity, were collected in a form of two-dimensional spatial maps. Throughout the analysis of these maps, the wafers' homogeneity and precision of the growth procedure were investigated. A very small variation of PL peak energy over the wafer indicates InAs quantum well width fluctuation of only a fraction of a monolayer and hence extraordinary thickness accuracy, a conclusion further supported by high uniformity of both the emission intensity and PL linewidth.
KW  - interband cascade lasers
KW  - fourier transform spectroscopy
KW  - mid-infrared
KW  - type II quantum wells
KW  - spatially resolved photoluminescence
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-139733
VL  - 10
IS  - 402
ER  - 
TY  - JOUR
A1  - Yu, Leo
A1  - Natarajan, Chandra M.
A1  - Horikiri, Tomoyuki
A1  - Langrock, Carsten
A1  - Pelc, Jason S.
A1  - Tanner, Michael G.
A1  - Abe, Eisuke
A1  - Maier, Sebastian
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Kamp, Martin
A1  - Hadfield, Robert H.
A1  - Fejer, Martin M.
A1  - Yamamoto, Yoshihisa
T1  - Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits
JF  - Nature Communications
N2  - Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances.
KW  - atom
KW  - 1550 nm
KW  - up-conversion
KW  - heralded entanglement
KW  - emission
KW  - interface
KW  - generation
KW  - communication
KW  - downconversion
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138677
VL  - 6
ER  - 
TY  - JOUR
A1  - Tempel, Jean-Sebastian
A1  - Veit, Tempel
A1  - Assmann, Marc
A1  - Kreilkamp, Lars Erik
A1  - Höfling, Sven
A1  - Kamp, Martin
A1  - Forchel, Alfred
A1  - Bayer, Manfred
T1  - Temperature dependence of pulsed polariton lasing in a GaAs microcavity
JF  - New Journal of Physics
N2  - The second-order correlation function g\(^2\)(\(\tau\) = 0), input-output curves and pulse duration of the emission from a microcavity exciton-polariton system subsequent to picosecond-pulsed excitation are measured for different temperatures. At low temperatures a two-threshold behaviour emerges, which has been attributed to the onset of polariton lasing and conventional lasing at the first and the second threshold, respectively. We observe that polariton lasing is stable up to temperatures comparable with the exciton binding energy. At higher temperatures a single threshold displays the direct transition from thermal emission to photon lasing.
KW  - semiconductor microavity
KW  - quantized vortices
KW  - cavity polaritons
KW  - room temperature
KW  - excitons
KW  - time
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134022
VL  - 14
IS  - 083014
ER  - 
TY  - JOUR
A1  - Rau, Markus
A1  - Heindel, Tobias
A1  - Unsleber, Sebastian
A1  - Braun, Tristan
A1  - Fischer, Julian
A1  - Frick, Stefan
A1  - Nauerth, Sebastian
A1  - Schneider, Christian
A1  - Vest, Gwenaelle
A1  - Reitzenstein, Stephan
A1  - Kamp, Martin
A1  - Forchel, Alfred
A1  - Höfling, Sven
A1  - Weinfurter, Harald
T1  - Free space quantum key distribution over 500 meters using electrically driven quantum dot single-photon sources-a proof of principle experiment
JF  - New Journal of Physics
N2  - Highly efficient single-photon sources (SPS) can increase the secure key rate of quantum key distribution (QKD) systems compared to conventional attenuated laser systems. Here we report on a free space QKD test using an electrically driven quantum dot single-photon source (QD SPS) that does not require a separate laser setup for optical pumping and thus allows for a simple and compact SPS QKD system. We describe its implementation in our 500 m free space QKD system in downtown Munich. Emulating a BB84 protocol operating at a repetition rate of 125 MHz, we could achieve sifted key rates of 5-17 kHz with error ratios of 6-9% and g((2))(0)-values of 0.39-0.76.
KW  - QKD
KW  - electrically driven
KW  - free space
KW  - quantum dots
KW  - quantum key distribution
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-116760
VL  - 16
IS  - 043003
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  - Lee, Eun-Hye
A1  - Song, Jin-Dong
A1  - Han, Il-Ki
A1  - Chang, Soo-Kyung
A1  - Langer, Fabian
A1  - Höfling, Sven
A1  - Forchel, Alfred
A1  - Kamp, Martin
A1  - Kim, Jong-Su
T1  - Structural and optical properties of position-retrievable low-density GaAs droplet epitaxial quantum dots for application to single photon sources with plasmonic optical coupling
JF  - Nanoscale Research Letters
N2  - The position of a single GaAs quantum dot (QD), which is optically active, grown by low-density droplet epitaxy (DE) (approximately 4 QDs/μm\(^{2}\)), was directly observed on the surface of a 45-nm-thick Al\(_{0.3}\)Ga\(_{0.7}\)As capping layer. The thin thickness of AlGaAs capping layer is useful for single photon sources with plasmonic optical coupling. A micro-photoluminescence for GaAs DE QDs has shown exciton/biexciton behavior in the range of 1.654 to 1.657 eV. The direct observation of positions of low-density GaAs DE QDs would be advantageous for mass fabrication of devices that use a single QD, such as single photon sources.
KW  - quantum dot
KW  - droplet epitaxy
KW  - micro-photoluminescence
KW  - single photon
KW  - GaAs
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143692
VL  - 10
IS  - 114
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  - 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  - Jahnke, Frank
A1  - Gies, Christopher
A1  - Aßmann, Marc
A1  - Bayer, Manfred
A1  - Leymann, H.A.M.
A1  - Foerster, Alexander
A1  - Wiersig, Jan
A1  - Schneider, Christian
A1  - Kamp, Martin
A1  - Höfling, Sven
T1  - Giant photon bunching, superradiant pulse emission and excitation trapping in quantum-dot nanolasers
JF  - Nature Communications
N2  - Light is often characterized only by its classical properties, like intensity or coherence. When looking at its quantum properties, described by photon correlations, new information about the state of the matter generating the radiation can be revealed. In particular the difference between independent and entangled emitters, which is at the heart of quantum mechanics, can be made visible in the photon statistics of the emitted light. The well-studied phenomenon of superradiance occurs when quantum–mechanical correlations between the emitters are present. Notwithstanding, superradiance was previously demonstrated only in terms of classical light properties. Here, we provide the missing link between quantum correlations of the active material and photon correlations in the emitted radiation. We use the superradiance of quantum dots in a cavity-quantum electrodynamics laser to show a direct connection between superradiant pulse emission and distinctive changes in the photon correlation function. This directly demonstrates the importance of quantum–mechanical correlations and their transfer between carriers and photons in novel optoelectronic devices.
KW  - photon bunching
KW  - quantum mechanics
KW  - superradiant pulse emission
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166144
VL  - 7
IS  - 11540
ER  - 
TY  - JOUR
A1  - Dietrich, Christof P.
A1  - Steude, Anja
A1  - Tropf, Laura
A1  - Schubert, Marcel
A1  - Kronenberg, Nils M.
A1  - Ostermann, Kai
A1  - Höfling, Sven
A1  - Gather, Malte C.
T1  - An exciton-polariton laser based on biologically produced fluorescent protein
JF  - Science Advances
N2  - Under adequate conditions, cavity polaritons form a macroscopic coherent quantum state, known as polariton condensate. Compared to Wannier-Mott excitons in inorganic semiconductors, the localized Frenkel excitons in organic emitter materials show weaker interaction with each other but stronger coupling to light, which recently enabled the first realization of a polariton condensate at room temperature. However, this required ultrafast optical pumping, which limits the applications of organic polariton condensates. We demonstrate room temperature polariton condensates of cavity polaritons in simple laminated microcavities filled with biologically produced enhanced green fluorescent protein (eGFP). The unique molecular structure of eGFP prevents exciton annihilation even at high excitation densities, thus facilitating polariton condensation under conventional nanosecond pumping. Condensation is clearly evidenced by a distinct threshold, an interaction-induced blueshift of the condensate, long-range coherence, and the presence of a second threshold at higher excitation density that is associated with the onset of photon lasing.
KW  - polarition condensate
KW  - enhanced green fluorescent protein
KW  - photon lasing
KW  - quantum physics
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-171305
VL  - 2
IS  - 8
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  - 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  - 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  - Horikiri, Tomoyuki
A1  - Yamaguchi, Makoto
A1  - Kamide, Kenji
A1  - Matsuo, Yasuhiro
A1  - Byrnes, Tim
A1  - Ishida, Natsuko
A1  - Löffler, Andreas
A1  - Höfling, Sven
A1  - Shikano, Yutaka
A1  - Ogawa, Tetsuo
A1  - Forchel, Alfred
A1  - Yamamoto, Yoshihisa
T1  - High-energy side-peak emission of exciton-polariton condensates in high density regime
JF  - Scientific Reports
N2  - In a standard semiconductor laser, electrons and holes recombine via stimulated emission to emit coherent light, in a process that is far from thermal equilibrium. Exciton-polariton condensates–sharing the same basic device structure as a semiconductor laser, consisting of quantum wells coupled to a microcavity–have been investigated primarily at densities far below the Mott density for signatures of Bose-Einstein condensation. At high densities approaching the Mott density, exciton-polariton condensates are generally thought to revert to a standard semiconductor laser, with the loss of strong coupling. Here, we report the observation of a photoluminescence sideband at high densities that cannot be accounted for by conventional semiconductor lasing. This also differs from an upper-polariton peak by the observation of the excitation power dependence in the peak-energy separation. Our interpretation as a persistent coherent electron-hole-photon coupling captures several features of this sideband, although a complete understanding of the experimental data is lacking. A full understanding of the observations should lead to a development in non-equilibrium many-body physics.
KW  - side-peak emission
KW  - exciton-polariton condensates
KW  - standard semiconductor laser
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167711
VL  - 6
IS  - 25655
ER  - 
TY  - JOUR
A1  - Lee, Chang-Min
A1  - Lim, Hee-Jin
A1  - Schneider, Christian
A1  - Maier, Sebastian
A1  - Höfling, Sven
A1  - Kamp, Martin
A1  - Lee, Yong-Hee
T1  - Efficient single photon source based on \(\mu\)-fibre-coupled tunable microcavity
JF  - Scientific Reports
N2  - Efficient and fast on-demand single photon sources have been sought after as critical components of quantum information science. We report an efficient and tunable single photon source based on an InAs quantum dot (QD) embedded in a photonic crystal cavity coupled with a highly curved \(\mu\)-fibre. Exploiting evanescent coupling between the \(\mu\)-fibre and the cavity, a high collection efficiency of 23% and Purcell-enhanced spontaneous emissions are observed. In our scheme, the spectral position of a resonance can be tuned by as much as 1.5 nm by adjusting the contact position of the \(\mu\)-fibre, which increases the spectral coupling probability between the QD and the cavity mode. Taking advantage of the high photon count rate and the tunability, the collection efficiencies and the decay rates are systematically investigated as a function of the QD-cavity detuning.
KW  - tapers
KW  - semiconductor quantum dots
KW  - crystal
KW  - nanowire
KW  - generation
KW  - nanoactivity
KW  - mode
KW  - emission
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145835
VL  - 5
IS  - 14309
ER  - 
TY  - JOUR
A1  - Wurdack, Matthias
A1  - Lundt, Nils
A1  - Klaas, Martin
A1  - Baumann, Vasilij
A1  - Kavokin, Alexey V.
A1  - Höfling, Sven
A1  - Schneider, Christian
T1  - Observation of hybrid Tamm-plasmon exciton-polaritons with GaAs quantum wells and a MoSe\(_{2}\) monolayer
JF  - Nature Communications
N2  - Strong light matter coupling between excitons and microcavity photons, as described in the framework of cavity quantum electrodynamics, leads to the hybridization of light and matter excitations. The regime of collective strong coupling arises, when various excitations from different host media are strongly coupled to the same optical resonance. This leads to a well-controllable admixture of various matter components in three hybrid polariton modes. Here, we study a cavity device with four embedded GaAs quantum wells hosting excitons that are spectrally matched to the A-valley exciton resonance of a MoSe\(_{2}\) monolayer. The formation of hybrid polariton modes is evidenced in momentum resolved photoluminescence and reflectivity studies. We describe the energy and k-vector distribution of exciton-polaritons along the hybrid modes by a thermodynamic model, which yields a very good agreement with the experiment.
KW  - two-dimensional materials
KW  - microresonators
KW  - nanophotonics and plasmonics
KW  - cavity device
KW  - strong coupling
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170480
VL  - 8
IS  - 259
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  - 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  -