@article{36471, abstract = {{Superconducting nanowire single-photon detectors (SNSPDs) show near unity efficiency, low dark count rate, and short recovery time. Combining these characteristics with temporal control of SNSPDs broadens their applications as in active de-latching for higher dynamic range counting or temporal filtering for pump-probe spectroscopy or LiDAR. To that end, we demonstrate active gating of an SNSPD with a minimum off-to-on rise time of 2.4 ns and a total gate length of 5.0 ns. We show how the rise time depends on the inductance of the detector in combination with the control electronics. The gate window is demonstrated to be fully and freely, electrically tunable up to 500 ns at a repetition rate of 1.0 MHz, as well as ungated, free-running operation. Control electronics to generate the gating are mounted on the 2.3 K stage of a closed-cycle sorption cryostat, while the detector is operated on the cold stage at 0.8 K. We show that the efficiency and timing jitter of the detector is not altered during the on-time of the gating window. We exploit gated operation to demonstrate a method to increase in the photon counting dynamic range by a factor 11.2, as well as temporal filtering of a strong pump in an emulated pump-probe experiment.}}, author = {{Hummel, Thomas and Widhalm, Alex and Höpker, Jan Philipp and Jöns, Klaus and Chang, Jin and Fognini, Andreas and Steinhauer, Stephan and Zwiller, Val and Zrenner, Artur and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{1}}, publisher = {{Optica Publishing Group}}, title = {{{Nanosecond gating of superconducting nanowire single-photon detectors using cryogenic bias circuitry}}}, doi = {{10.1364/oe.472058}}, volume = {{31}}, year = {{2023}}, } @article{29716, author = {{Widhalm, Alex and Golla, Christian and Weber, Nils and Mackwitz, Peter and Zrenner, Artur and Meier, Cedrik}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{4}}, publisher = {{The Optical Society}}, title = {{{Electric-field-induced second harmonic generation in silicon dioxide}}}, doi = {{10.1364/oe.443489}}, volume = {{30}}, year = {{2022}}, } @article{30385, abstract = {{AbstractTailored nanoscale quantum light sources, matching the specific needs of use cases, are crucial building blocks for photonic quantum technologies. Several different approaches to realize solid-state quantum emitters with high performance have been pursued and different concepts for energy tuning have been established. However, the properties of the emitted photons are always defined by the individual quantum emitter and can therefore not be controlled with full flexibility. Here we introduce an all-optical nonlinear method to tailor and control the single photon emission. We demonstrate a laser-controlled down-conversion process from an excited state of a semiconductor quantum three-level system. Based on this concept, we realize energy tuning and polarization control of the single photon emission with a control-laser field. Our results mark an important step towards tailored single photon emission from a photonic quantum system based on quantum optical principles.}}, author = {{Jonas, B. and Heinze, D. and Schöll, E. and Kallert, P. and Langer, T. and Krehs, S. and Widhalm, A. and Jöns, K. D. and Reuter, D. and Schumacher, S. and Zrenner, Artur}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, keywords = {{General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Nonlinear down-conversion in a single quantum dot}}}, doi = {{10.1038/s41467-022-28993-3}}, volume = {{13}}, year = {{2022}}, } @article{30384, author = {{Praschan, Tom and Heinze, Dirk and Breddermann, Dominik and Zrenner, Artur and Walther, Andrea and Schumacher, Stefan}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{4}}, publisher = {{American Physical Society (APS)}}, title = {{{Pulse shaping for on-demand emission of single Raman photons from a quantum-dot biexciton}}}, doi = {{10.1103/physrevb.105.045302}}, volume = {{105}}, year = {{2022}}, } @article{40523, abstract = {{AbstractTailored nanoscale quantum light sources, matching the specific needs of use cases, are crucial building blocks for photonic quantum technologies. Several different approaches to realize solid-state quantum emitters with high performance have been pursued and different concepts for energy tuning have been established. However, the properties of the emitted photons are always defined by the individual quantum emitter and can therefore not be controlled with full flexibility. Here we introduce an all-optical nonlinear method to tailor and control the single photon emission. We demonstrate a laser-controlled down-conversion process from an excited state of a semiconductor quantum three-level system. Based on this concept, we realize energy tuning and polarization control of the single photon emission with a control-laser field. Our results mark an important step towards tailored single photon emission from a photonic quantum system based on quantum optical principles.}}, author = {{Jonas, B. and Heinze, Dirk Florian and Schöll, E. and Kallert, P. and Langer, T. and Krehs, S. and Widhalm, A. and Jöns, Klaus and Reuter, Dirk and Schumacher, Stefan and Zrenner, Artur}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, keywords = {{General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Nonlinear down-conversion in a single quantum dot}}}, doi = {{10.1038/s41467-022-28993-3}}, volume = {{13}}, year = {{2022}}, } @article{40431, author = {{Praschan, Tom and Heinze, Dirk and Breddermann, Dominik and Zrenner, Artur and Walther, Andrea and Schumacher, Stefan}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{4}}, publisher = {{American Physical Society (APS)}}, title = {{{Pulse shaping for on-demand emission of single Raman photons from a quantum-dot biexciton}}}, doi = {{10.1103/physrevb.105.045302}}, volume = {{105}}, year = {{2022}}, } @misc{40428, author = {{Jonas, Björn and Heinze, Dirk Florian and Schöll, Eva and Kallert, Patricia and Langer, Timo and Krehs, Sebastian and Widhalm, Alex and Jöns, Klaus and Reuter, Dirk and Zrenner, Artur}}, publisher = {{LibreCat University}}, title = {{{Nonlinear down-conversion in a single quantum dot}}}, doi = {{10.5281/ZENODO.6024228}}, year = {{2022}}, } @unpublished{22802, abstract = {{In our work, we have engineered low capacitance single quantum dot photodiodes as sensor devices for the optoelectronic sampling of ultrafast electric signals. By the Stark effect, a time-dependent electric signal is converted into a time-dependent shift of the transition energy. This shift is measured accurately by resonant ps laser spectroscopy with photocurrent detection. In our experiments, we sample the laser synchronous output pulse of an ultrafast CMOS circuit with high resolution. With our quantum dot sensor device, we were able to sample transients below 20 ps with a voltage resolution in the mV-range.}}, author = {{Widhalm, Alex and Krehs, Sebastian and Siebert, Dustin and Sharma, Nand Lal and Langer, Timo and Jonas, Björn and Reuter, Dirk and Thiede, Andreas and Förstner, Jens and Zrenner, Artur}}, booktitle = {{arXiv:2106.00994}}, title = {{{Optoelectronic sampling of ultrafast electric transients with single quantum dots}}}, year = {{2021}}, } @unpublished{22807, abstract = {{Photonic quantum technologies [1] with applications in quantum communication, sensing as well as quantum simulation and computing, are on the verge of becoming commercially available. One crucial building block are tailored nanoscale integratable quantum light sources, matching the specific needs of use-cases. Several different approaches to realize solid-state quantum emitters [2] with high performance [3] have been pursued. However, the properties of the emitted single photons are always defined by the individual quantum light source and despite numerous quantum emitter tuning techniques [4-7], scalability is still a major challenge. Here we show an emitter-independent method to tailor and control the properties of the single photon emission. We demonstrate a laser-controlled down-conversion process from an excited state of a quantum three-level system [8]. Starting from a biexciton state, a tunable control laser field defines a virtual state in a stimulated process. From there, spontaneous emission to the ground state leads to optically controlled single photon emission. Based on this concept, we demonstrate energy tuning of the single photon emission with a control laser field. The nature of the involved quantum states furthermore provides a unique basis for the future control of polarization and bandwidth, as predicted by theory [9,10]. Our demonstration marks an important step towards tailored single photon emission from a photonic quantum system based on quantum optical principles.}}, author = {{Jonas, B. and Heinze, D. and Schöll, E. and Kallert, P. and Langer, T. and Krehs, S. and Widhalm, A. and Jöns, K. D. and Reuter, D. and Schumacher, S. and Zrenner, Artur}}, booktitle = {{arXiv:2105.12393}}, title = {{{Nonlinear down-conversion in a single quantum dot}}}, year = {{2021}}, } @article{27099, abstract = {{In our work, we have engineered low capacitance single quantum dot photodiodes as sensor devices for the optoelectronic sampling of ultrafast electric signals. By the Stark effect, a time-dependent electric signal is converted into a time-dependent shift of the transition energy. This shift is measured accurately by resonant ps laser spectroscopy with photocurrent detection. In our experiments, we sample the laser synchronous output pulse of an ultrafast CMOS circuit with high resolution. With our quantum dot sensor device, we were able to sample transients below 20 ps with a voltage resolution in the mV-range.}}, author = {{Widhalm, Alex and Krehs, Sebastian and Siebert, Dustin and Sharma, Nand Lal and Langer, Timo and Jonas, Björn and Reuter, Dirk and Thiede, Andreas and Förstner, Jens and Zrenner, Artur}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, keywords = {{tet_topic_qd}}, pages = {{181109}}, title = {{{Optoelectronic sampling of ultrafast electric transients with single quantum dots}}}, doi = {{10.1063/5.0061358}}, volume = {{119}}, year = {{2021}}, } @article{23826, abstract = {{Potassium titanyl phosphate (KTP) is a nonlinear optical material with applications in high-power frequency conversion or quasi-phase matching in submicron period domain grids. A prerequisite for these applications is a precise control and understanding of the poling mechanisms to enable the fabrication of high-grade domain grids. In contrast to the widely used material lithium niobate, the domain growth in KTP is less studied, because many standard methods, such as selective etching or polarization microscopy, provides less insight or are not applicable on non-polar surfaces, respectively. In this work, we present results of confocal Raman-spectroscopy of the ferroelectric domain structure in KTP. This analytical method allows for the visualization of domain grids of the non-polar KTP y-face and therefore more insight into the domain-growth and -structure in KTP, which can be used for improved domain fabrication.}}, author = {{Brockmeier, Julian and Mackwitz, Peter Walter Martin and Rüsing, Michael and Eigner, Christof and Padberg, Laura and Santandrea, Matteo and Silberhorn, Christine and Zrenner, Artur and Berth, Gerhard}}, issn = {{2073-4352}}, journal = {{Crystals}}, title = {{{Non-Invasive Visualization of Ferroelectric Domain Structures on the Non-Polar y-Surface of KTiOPO4 via Raman Imaging}}}, doi = {{10.3390/cryst11091086}}, year = {{2021}}, } @article{22054, author = {{Spychala, K. J. and Mackwitz, P. and Widhalm, A. and Berth, Gerhard and Zrenner, Artur}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, title = {{{Spatially resolved light field analysis of the second-harmonic signal of χ(2)-materials in the tight focusing regime}}}, doi = {{10.1063/1.5133476}}, year = {{2020}}, } @article{17322, author = {{Mukherjee, Amlan and Widhalm, Alex and Siebert, Dustin and Krehs, Sebastian and Sharma, Nandlal and Thiede, Andreas and Reuter, Dirk and Förstner, Jens and Zrenner, Artur}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, keywords = {{tet_topic_qd}}, pages = {{251103}}, title = {{{Electrically controlled rapid adiabatic passage in a single quantum dot}}}, doi = {{10.1063/5.0012257}}, volume = {{116}}, year = {{2020}}, } @inproceedings{39966, author = {{Förstner, Jens and Widhalm, A. and Mukherjee, A. and Krehs, S. and Jonas, B. and Spychala, K. and Förstner, Jens and Thiede, Andreas and Reuter, Dirk and Zrenner, Artur}}, booktitle = {{11th International Conference on Quantum Dots}}, title = {{{Ultrafast electric control of a single QD exciton}}}, year = {{2020}}, } @article{22056, author = {{Spychala, K. J. and Mackwitz, P. and Rüsing, Michael and Widhalm, A. and Berth, Gerhard and Silberhorn, Christine and Zrenner, Artur}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, title = {{{Nonlinear focal mapping of ferroelectric domain walls in LiNbO3: Analysis of the SHG microscopy contrast mechanism}}}, doi = {{10.1063/5.0025284}}, year = {{2020}}, } @article{25920, author = {{Padberg, Laura and Santandrea, Matteo and Rüsing, Michael and Brockmeier, Julian and Mackwitz, Peter and Berth, Gerhard and Zrenner, Artur and Eigner, Christof and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Characterisation of width-dependent diffusion dynamics in rubidium-exchanged KTP waveguides}}}, doi = {{10.1364/oe.397074}}, year = {{2020}}, } @article{3427, abstract = {{We report on the coherent phase manipulation of quantum dot excitons by electric means. For our experiments, we use a low capacitance single quantum dot photodiode which is electrically controlled by a custom designed SiGe:C BiCMOS chip. The phase manipulation is performed and quantified in a Ramsey experiment, where ultrafast transient detuning of the exciton energy is performed synchronous to double pulse p/2 ps laser excitation. We are able to demonstrate electrically controlled phase manipulations with magnitudes up to 3p within 100 ps which is below the dephasing time of the quantum dot exciton.}}, author = {{Widhalm, Alex and Mukherjee, Amlan and Krehs, Sebastian and Sharma, Nandlal and Kölling, Peter and Thiede, Andreas and Reuter, Dirk and Förstner, Jens and Zrenner, Artur}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, keywords = {{tet_topic_qd}}, number = {{11}}, pages = {{111105}}, title = {{{Ultrafast electric phase control of a single exciton qubit}}}, doi = {{10.1063/1.5020364}}, volume = {{112}}, year = {{2018}}, } @article{4769, abstract = {{In recent years, Raman spectroscopy has been used to visualize and analyze ferroelectric domain structures. The technique makes use of the fact that the intensity or frequency of certain phonons is strongly influenced by the presence of domain walls. Although the method is used frequently, the underlying mechanism responsible for the changes in the spectra is not fully understood. This inhibits deeper analysis of domain structures based on this method. Two different models have been proposed. However, neither model completely explains all observations. In this work, we have systematically investigated domain walls in different scattering geometries with Raman spectroscopy in the common ferroelectric materials used in integrated optics, i.e., KTiOPO4, LiNbO3, and LiTaO3. Based on the two models, we can demonstrate that the observed contrast for domain walls is in fact based on two different effects. We can identify on the one hand microscopic changes at the domain wall, e.g., strain and electric fields, and on the other hand a macroscopic change of selection rules at the domain wall. While the macroscopic relaxation of selection rules can be explained by the directional dispersion of the phonons in agreement with previous propositions, the microscopic changes can be explained qualitatively in terms of a simplified atomistic model.}}, author = {{Rüsing, Michael and Neufeld, Sergej and Brockmeier, Julian and Eigner, Christof and Mackwitz, P. and Spychala, K. and Silberhorn, Christine and Schmidt, Wolf Gero and Berth, Gerhard and Zrenner, Artur and Sanna, S.}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{10}}, publisher = {{American Physical Society (APS)}}, title = {{{Imaging of 180∘ ferroelectric domain walls in uniaxial ferroelectrics by confocal Raman spectroscopy: Unraveling the contrast mechanism}}}, doi = {{10.1103/physrevmaterials.2.103801}}, volume = {{2}}, year = {{2018}}, } @article{3433, abstract = {{In this article we demonstrate a fully CMOS compatible fabrication process for the realization of microdisk resonators based on silicon oxynitride. The layer fabrication using plasma enhanced chemical vapor deposition is optimized in terms of surface roughness and internal material absorption. Resulting surface roughness due to the etching process is reduced by using optimized etching parameters. Whispering gallery modes of the fabricated microdisk resonators have been investigated by tapered fiber coupling and show quality factors as high as 10 6.}}, author = {{Hett, T. and Krämmer, S. and Hilleringmann, U. and Kalt, H. and Zrenner, Artur}}, issn = {{0022-2313}}, journal = {{JOURNAL OF LUMINESCENCE}}, pages = {{131----134}}, title = {{{High-Q whispering gallery microdisk resonators based on silicon oxynitride}}}, doi = {{10.1016/j.jlumin.2016.11.016}}, year = {{2017}}, } @article{3435, abstract = {{Semiconductor quantum dots are promising sources for polarization-entangled photons. As an alternative to the usual cascaded biexciton-exciton emission, direct two-photon emission from the biexciton can be used. With a high-quality optical resonator tuned to half the biexciton energy, a large proportion of the photons can be steered into the two-photon emission channel. In this case the degree of polarization entanglement is inherently insensitive to the exciton fine-structure splitting. In the present work we analyze the biexciton emission with particular emphasis on the influence of coupling of the quantum-dot cavity system to its environment. Especially for a high-quality cavity, the coupling to the surrounding semiconductormaterial can open up additional phonon-assisted decay channels. Our analysis demonstrates that with the cavity tuned to half the biexciton energy, the potentially detrimental influence of the phonons on the polarization entanglement is strongly suppressed—high degrees of entanglement can still be achieved. We further discuss spectral properties and statistics of the emitted twin photons.}}, author = {{Heinze, Dirk and Zrenner, Artur and Schumacher, Stefan}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{24}}, title = {{{Polarization-entangled twin photons from two-photon quantum-dot emission}}}, doi = {{10.1103/PhysRevB.95.245306}}, year = {{2017}}, }