@article{51339, author = {{Babai-Hemati, Jonas and vom Bruch, Felix and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, publisher = {{Optica Publishing Group}}, title = {{{Tailored second harmonic generation inTi-diffused PPLN waveguides usingmicro-heaters}}}, doi = {{10.1364/oe.510319}}, year = {{2024}}, } @article{51356, abstract = {{Abstract Lithium niobate has emerged as a promising platform for integrated quantum optics, enabling efficient generation, manipulation, and detection of quantum states of light. However, integrating single-photon detectors requires cryogenic operating temperatures, since the best performing detectors are based on narrow superconducting wires. While previous studies have demonstrated the operation of quantum light sources and electro-optic modulators in LiNbO3 at cryogenic temperatures, the thermal transition between room temperature and cryogenic conditions introduces additional effects that can significantly influence device performance. In this paper, we investigate the generation of pyroelectric charges and their impact on the optical properties of lithium niobate waveguides when changing from room temperature to 25 K, and vice versa. We measure the generated pyroelectric charge flow and correlate this with fast changes in the birefringence acquired through the Sénarmont-method. Both electrical and optical influence of the pyroelectric effect occur predominantly at temperatures above 100 K.}}, author = {{Thiele, Frederik and Hummel, Thomas and Lange, Nina Amelie and Dreher, Felix and Protte, Maximilian and Bruch, Felix vom and Lengeling, Sebastian and Herrmann, Harald and Eigner, Christof and Silberhorn, Christine and Bartley, Tim}}, issn = {{2633-4356}}, journal = {{Materials for Quantum Technology}}, keywords = {{General Earth and Planetary Sciences, General Environmental Science}}, number = {{1}}, publisher = {{IOP Publishing}}, title = {{{Pyroelectric influence on lithium niobate during the thermal transition for cryogenic integrated photonics}}}, doi = {{10.1088/2633-4356/ad207d}}, volume = {{4}}, year = {{2024}}, } @article{45850, abstract = {{Interference between single photons is key for many quantum optics experiments and applications in quantum technologies, such as quantum communication or computation. It is advantageous to operate the systems at telecommunication wavelengths and to integrate the setups for these applications in order to improve stability, compactness and scalability. A new promising material platform for integrated quantum optics is lithium niobate on insulator (LNOI). Here, we realise Hong-Ou-Mandel (HOM) interference between telecom photons from an engineered parametric down-conversion source in an LNOI directional coupler. The coupler has been designed and fabricated in house and provides close to perfect balanced beam splitting. We obtain a raw HOM visibility of (93.5 ± 0.7) %, limited mainly by the source performance and in good agreement with off-chip measurements. This lays the foundation for more sophisticated quantum experiments in LNOI.}}, author = {{Babel, Silia and Bollmers, Laura and Massaro, Marcello and Luo, Kai Hong and Stefszky, Michael and Pegoraro, Federico and Held, Philip and Herrmann, Harald and Eigner, Christof and Brecht, Benjamin and Padberg, Laura and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{14}}, publisher = {{Optica Publishing Group}}, title = {{{Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler}}}, doi = {{10.1364/oe.484126}}, volume = {{31}}, year = {{2023}}, } @article{46138, abstract = {{This work reports a fully guided setup for single-mode squeezing on integrated titanium-indiffused periodically poled nonlinear resonators. A continuous-wave laser beam is delivered and the squeezed field is collected by single-mode fibers; up to −3.17(9) dB of useful squeezing is available in fibers. To showcase the usefulness of such a fiber-coupled device, we applied the generated squeezed light in a fiber-based phase sensing experiment, showing a quantum enhancement in the signal-to-noise ratio of 0.35 dB. Moreover, our investigation of the effect of photorefraction on the cavity resonance condition suggests that it causes system instabilities at high powers.}}, author = {{Domeneguetti, Renato and Stefszky, Michael and Herrmann, Harald and Silberhorn, Christine and Andersen, Ulrik L. and Neergaard-Nielsen, Jonas S. and Gehring, Tobias}}, issn = {{0146-9592}}, journal = {{Optics Letters}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{11}}, publisher = {{Optica Publishing Group}}, title = {{{Fully guided and phase locked Ti:PPLN waveguide squeezing for applications in quantum sensing}}}, doi = {{10.1364/ol.486654}}, volume = {{48}}, year = {{2023}}, } @article{46644, abstract = {{A reliable, but cost-effective generation of single-photon states is key for practical quantum communication systems. For real-world deployment, waveguide sources offer optimum compatibility with fiber networks and can be embedded in hybrid integrated modules. Here, we present what we believe to be the first chip-size fully integrated fiber-coupled heralded single photon source (HSPS) module based on a hybrid integration of a nonlinear lithium niobate waveguide into a polymer board. Photon pairs at 810 nm (signal) and 1550 nm (idler) are generated via parametric down-conversion pumped at 532 nm in the LiNbO3 waveguide. The pairs are split in the polymer board and routed to separate output ports. The module has a size of (2 × 1) cm^2 and is fully fiber-coupled with one pump input fiber and two output fibers. We measure a heralded second-order correlation function of g_h(2)=0.05 with a heralding efficiency of η_h=3.5% at low pump powers}}, author = {{Kießler, Christian and Conradi, Hauke and Kleinert, Moritz and Quiring, Viktor and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{14}}, publisher = {{Optica Publishing Group}}, title = {{{Fiber-coupled plug-and-play heralded single photon source based on Ti:LiNbO3 and polymer technology}}}, doi = {{10.1364/oe.487581}}, volume = {{31}}, year = {{2023}}, } @article{33672, abstract = {{Abstract Lithium niobate is a promising platform for integrated quantum optics. In this platform, we aim to efficiently manipulate and detect quantum states by combining superconducting single photon detectors and modulators. The cryogenic operation of a superconducting single photon detector dictates the optimisation of the electro-optic modulators under the same operating conditions. To that end, we characterise a phase modulator, directional coupler, and polarisation converter at both ambient and cryogenic temperatures. The operation voltage V π / 2 of these modulators increases, due to the decrease in the electro-optic effect, by 74% for the phase modulator, 84% for the directional coupler and 35% for the polarisation converter below 8.5 K . The phase modulator preserves its broadband nature and modulates light in the characterised wavelength range. The unbiased bar state of the directional coupler changed by a wavelength shift of 85 n m while cooling the device down to 5 K . The polarisation converter uses periodic poling to phasematch the two orthogonal polarisations. The phasematched wavelength of the utilised poling changes by 112 n m when cooling to 5 K .}}, author = {{Thiele, Frederik and vom Bruch, Felix and Brockmeier, Julian and Protte, Maximilian and Hummel, Thomas and Ricken, Raimund and Quiring, Viktor and Lengeling, Sebastian and Herrmann, Harald and Eigner, Christof and Silberhorn, Christine and Bartley, Tim}}, issn = {{2515-7647}}, journal = {{Journal of Physics: Photonics}}, keywords = {{Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials}}, number = {{3}}, publisher = {{IOP Publishing}}, title = {{{Cryogenic electro-optic modulation in titanium in-diffused lithium niobate waveguides}}}, doi = {{10.1088/2515-7647/ac6c63}}, volume = {{4}}, year = {{2022}}, } @article{38532, author = {{Trenti, Alessandro and Achleitner, Martin and Prawits, Florian and Schrenk, Bernhard and Conradi, Hauke and Kleinert, Moritz and Incoronato, Alfonso and Zanetto, Francesco and Zappa, Franco and Luch, Ilaria Di and Cirkinoglu, Ozan and Leijtens, Xaveer and Bonardi, Antonio and Bruynsteen, Cedric and Yin, Xin and Kießler, Christian and Herrmann, Harald and Silberhorn, Christine and Bozzio, Mathieu and Walther, Philip and Thiel, Hannah C. and Weihs, Gregor and Hubel, Hannes}}, issn = {{0733-8724}}, journal = {{Journal of Lightwave Technology}}, keywords = {{General Engineering}}, number = {{23}}, pages = {{7485--7497}}, publisher = {{Institute of Electrical and Electronics Engineers (IEEE)}}, title = {{{On-Chip Quantum Communication Devices}}}, doi = {{10.1109/jlt.2022.3201389}}, volume = {{40}}, year = {{2022}}, } @article{26221, author = {{Bartnick, Moritz and Santandrea, Matteo and Höpker, Jan Philipp and Thiele, Frederik and Ricken, Raimund and Quiring, Viktor and Eigner, Christof and Herrmann, Harald and Silberhorn, Christine and Bartley, Tim}}, issn = {{2331-7019}}, journal = {{Physical Review Applied}}, title = {{{Cryogenic Second-Harmonic Generation in Periodically Poled Lithium Niobate Waveguides}}}, doi = {{10.1103/physrevapplied.15.024028}}, year = {{2021}}, } @inproceedings{39027, abstract = {{We experimentally investigate the generation of continuous-wave optical squeezing from a titanium-indiffused lithium niobate waveguide resonator at low and high frequencies. The device promises integration with different platform chips for more complex optical systems.}}, author = {{Domeneguetti, Renato R. and Conradi, Hauke and Kleinert, Moritz and Kießler, Christian and Stefszky, Michael and Herrmann, Harald and Silberhorn, Christine and Andersen, Ulrik L. and Neergaard-Nielsen, Jonas Schou and Gehring, Tobias}}, booktitle = {{2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference}}, keywords = {{Optical systems, Polymer waveguides, Quantum key distribution, Quantum light sources, Squeezed states, Waveguides}}, pages = {{eb_4_1}}, publisher = {{Optica Publishing Group}}, title = {{{Nonlinear waveguides for integrated quantum light source}}}, year = {{2021}}, } @inproceedings{40374, abstract = {{We present a frequency multimode integrated SU (1,1) interferometer with a polarization converter and strong signal-idler photon correlations. Phase sensitivity below the shot noise limit is demonstrated, various filtering and seeding strategies are discussed.}}, author = {{Ferreri, A. and Santandrea, Matteo and Stefszky, Michael and Luo, Kai Hong and Herrmann, Harald and Silberhorn, Christine and Sharapova, Polina}}, booktitle = {{Conference on Lasers and Electro-Optics}}, publisher = {{Optica Publishing Group}}, title = {{{Multimode integrated SU(1,1) interferometer}}}, doi = {{10.1364/cleo_qels.2021.ftu1n.6}}, year = {{2021}}, } @article{26077, abstract = {{Nonlinear SU(1,1) interferometers are fruitful and promising tools for spectral engineering and precise measurements with phase sensitivity below the classical bound. Such interferometers have been successfully realized in bulk and fiber-based configurations. However, rapidly developing integrated technologies provide higher efficiencies, smaller footprints, and pave the way to quantum-enhanced on-chip interferometry. In this work, we theoretically realised an integrated architecture of the multimode SU(1,1) interferometer which can be applied to various integrated platforms. The presented interferometer includes a polarization converter between two photon sources and utilizes a continuous-wave (CW) pump. Based on the potassium titanyl phosphate (KTP) platform, we show that this configuration results in almost perfect destructive interference at the output and supersensitivity regions below the classical limit. In addition, we discuss the fundamental difference between single-mode and highly multimode SU(1,1) interferometers in the properties of phase sensitivity and its limits. Finally, we explore how to improve the phase sensitivity by filtering the output radiation and using different seeding states in different modes with various detection strategies.}}, author = {{Ferreri, Alessandro and Santandrea, Matteo and Stefszky, Michael and Luo, Kai Hong and Herrmann, Harald and Silberhorn, Christine and Sharapova, Polina R.}}, issn = {{2521-327X}}, journal = {{Quantum}}, title = {{{Spectrally multimode integrated SU(1,1) interferometer}}}, doi = {{10.22331/q-2021-05-27-461}}, year = {{2021}}, } @article{26889, author = {{Luo, Kai Hong and Santandrea, Matteo and Stefszky, Michael and Sperling, Jan and Massaro, Marcello and Ferreri, Alessandro and Sharapova, Polina and Herrmann, Harald and Silberhorn, Christine}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, title = {{{Quantum optical coherence: From linear to nonlinear interferometers}}}, doi = {{10.1103/physreva.104.043707}}, year = {{2021}}, } @article{22771, author = {{Stefszky, Michael and Santandrea, Matteo and vom Bruch, Felix and Krapick, S. and Eigner, Christof and Ricken, R. and Quiring, V. and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Waveguide resonator with an integrated phase modulator for second harmonic generation}}}, doi = {{10.1364/oe.412824}}, year = {{2020}}, } @article{20157, author = {{Thiele, Frederik and vom Bruch, Felix and Quiring, Victor and Ricken, Raimund and Herrmann, Harald and Eigner, Christof and Silberhorn, Christine and Bartley, Tim}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Cryogenic electro-optic polarisation conversion in titanium in-diffused lithium niobate waveguides}}}, doi = {{10.1364/oe.399818}}, year = {{2020}}, } @article{40271, author = {{Vergyris, Panagiotis and Babin, Charles and Nold, Raphael and Gouzien, Elie and Herrmann, Harald and Silberhorn, Christine and Alibart, Olivier and Tanzilli, Sébastien and Kaiser, Florian}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, keywords = {{Physics and Astronomy (miscellaneous)}}, number = {{2}}, publisher = {{AIP Publishing}}, title = {{{Two-photon phase-sensing with single-photon detection}}}, doi = {{10.1063/5.0009527}}, volume = {{117}}, year = {{2020}}, } @article{21025, author = {{Eigner, Christof and Padberg, Laura and Santandrea, Matteo and Herrmann, Harald and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{22}}, title = {{{Spatially single mode photon pair source at 800 nm in periodically poled Rubidium exchanged KTP waveguides}}}, doi = {{10.1364/oe.399483}}, volume = {{28}}, year = {{2020}}, } @article{25038, author = {{Massaro, Marcello and Meyer-Scott, Evan and Montaut, Nicola and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1367-2630}}, journal = {{New Journal of Physics}}, title = {{{Improving SPDC single-photon sources via extended heralding and feed-forward control}}}, doi = {{10.1088/1367-2630/ab1ec3}}, year = {{2019}}, } @article{26237, author = {{Luo, Kai-Hong and Ansari, Vahid and Massaro, Marcello and Santandrea, Matteo and Eigner, Christof and Ricken, Raimund and Herrmann, Harald and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Counter-propagating photon pair generation in a nonlinear waveguide}}}, doi = {{10.1364/oe.378789}}, year = {{2019}}, } @inproceedings{9635, author = {{Meyer-Scott, Evan and Prasannan, Nidhin and Montaut, Nicola and Tiedau, Johannes and Eigner, Christof and Harder, Georg and Sansoni, Linda and Nitsche, Thomas and Herrmann, Harald and Ricken, Raimund and Quiring, Viktor and Bartley, Tim and Barkhofen, Sonja and Silberhorn, Christine}}, booktitle = {{Advances in Photonics of Quantum Computing, Memory, and Communication XII}}, editor = {{Hasan, Zameer U. and Hemmer, Philip R. and Migdall, Alan L.}}, isbn = {{9781510625082}}, title = {{{Engineering integrated photon pair sources and multiplexed detectors (Conference Presentation)}}}, doi = {{10.1117/12.2513753}}, year = {{2019}}, } @article{12919, author = {{Georgi, Philip and Massaro, Marcello and Luo, Kai Hong and Sain, Basudeb and Montaut, Nicola and Herrmann, Harald and Weiss, Thomas and Li, Guixin and Silberhorn, Christine and Zentgraf, Thomas}}, issn = {{2047-7538}}, journal = {{Light: Science & Applications}}, pages = {{70}}, title = {{{Metasurface interferometry toward quantum sensors}}}, doi = {{10.1038/s41377-019-0182-6}}, volume = {{8}}, year = {{2019}}, }