@article{64864,
  abstract     = {{Probing novel properties, arising from twisted interfaces, has traditionally relied on the stacking of exfoliated two-dimensional materials and the spontaneous formation of van der Waals bonds. So far, investigations involving intimate covalent or ionic bonds have not been a focus. Yet, we show here that an established technique, involving thermocompressional wafer bonding, works well for creating twisted non-van der Waals interfaces. We have successfully bonded z-cut lithium niobate single crystals to create ferroelectric oxide interfaces with strong polar discontinuities and have mapped the associated emergent interfacial conductivity. In some instances, a dramatic change in microstructure occurs, involving local dipolar switching. A twist-induced collapse in the capability of the system to effec8tively screen interfacial bound charge is implied. Importantly, this only occurs around specific moiré twist angles with sparse coincident lattices and associated short-range aperiodicity. In quasicrystals, aperiodicity is known to induce pseudo-bandgaps and we suspect a similar phenomenon here.}},
  author       = {{Rogers, Andrew and Holsgrove, Kristina and Schäfer, Nils A. and Koppitz, Boris and McCluskey, Conor J. and Yedama, Shivani and Lynch, Ronan and Sloan, Keelan and Porter, Barry and Sykes, Adam and Catalan Daniels, Alex and Silva, Romualdo S. and Bruno, Flavio Y. and Seddon, Sam D. and Lu, Haidong and Rüsing, Michael and Fink, Christa and Fahler-Muenzer, Philipp and Fearn, Sarah and Heutz, Sandrine E. M. and Hadjimichael, Marios and Ramasse, Quentin M. and Alexe, Marin and Kumar, Amit and McQuaid, Raymond G. P. and Gruverman, Alexei and Sanna, Simone and Eng, Lukas M. and Gregg, J. Marty}},
  issn         = {{2041-1723}},
  journal      = {{Nature Communications}},
  number       = {{1}},
  publisher    = {{Springer Science and Business Media LLC}},
  title        = {{{Polar discontinuities, emergent conductivity, and critical twist-angle-dependent behaviour at wafer-bonded ferroelectric interfaces}}},
  doi          = {{10.1038/s41467-026-68553-7}},
  volume       = {{17}},
  year         = {{2026}},
}

@article{65094,
  abstract     = {{<jats:p>
                    The development of practical sensors for optical coherence tomography (OCT) with undetected photons requires miniaturization via integration. To be practical, these sensors must exhibit a large spectral bandwidth and a high brightness, which are linked to a high axial resolution and a sufficient signal-to-noise ratio, respectively. Here, we combine these requirements in a scheme for OCT measurements with undetected photons based on nonlinear
                    <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline">
                      <a:mi>Ti</a:mi>
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                      <a:msub>
                        <a:mrow>
                          <a:mi>Li</a:mi>
                          <a:mi>Nb</a:mi>
                          <a:mi mathvariant="normal">O</a:mi>
                        </a:mrow>
                        <a:mn>3</a:mn>
                      </a:msub>
                    </a:math>
                    waveguides. We investigate the performance benchmarks of the commonly used SU(1,1) scheme in comparison to an induced-coherence scheme and find that the latter is actually better suited when implementing measurements with undetected photons in integrated systems. In both schemes, we perform pump-gain optimization and OCT measurements with undetected photons with an axial resolution as low as
                    <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline">
                      <d:mn>28</d:mn>
                      <d:mspace width="0.2em"/>
                      <d:mtext fontfamily="times">μ</d:mtext>
                      <d:mrow>
                        <d:mi mathvariant="normal">m</d:mi>
                      </d:mrow>
                    </d:math>
                    .
                  </jats:p>}},
  author       = {{Roeder, Franz and Pollmann, René and Quiring, Viktor and Eigner, Christof and Brecht, Benjamin and Silberhorn, Christine}},
  issn         = {{2331-7019}},
  journal      = {{Physical Review Applied}},
  number       = {{3}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Toward integrated sensors for optimized optical coherence tomography with undetected photons}}},
  doi          = {{10.1103/cwsx-42c4}},
  volume       = {{25}},
  year         = {{2026}},
}

@article{65096,
  abstract     = {{<jats:p>
                    Precise measurements of both the arrival time and carrier frequency of light pulses are essential for time–frequency-encoded quantum technologies. Quantum mechanics, however, imposes fundamental limits on the simultaneous determination of these quantities. In this work, we derive and experimentally verify the quantum uncertainty bounds governing joint time–frequency measurements. We show that when detection is restricted to finite time windows, the problem is naturally described by a quantum rotor, rendering the commonly used Heisenberg uncertainty relation inapplicable. We further propose an optimal detection scheme that saturates these fundamental limits. By sampling the
                    <jats:italic toggle="yes">Q</jats:italic>
                    -function, we demonstrate the reconstruction of the Wigner function beyond the harmonic oscillator. Using an experimental implementation based on a quantum pulse gate, we confirm that the proposed scheme approaches the ultimate quantum limit for simultaneous time–frequency measurements. These results provide a framework for joint time–frequency detection with direct implications for precision measurements and quantum information processing.
                  </jats:p>}},
  author       = {{Folge, Patrick Fabian and Serino, Laura Maria and Mišta, Ladislav and Brecht, Benjamin and Silberhorn, Christine and Řeháček, Jaroslav and Hradil, Zdeněk}},
  issn         = {{2334-2536}},
  journal      = {{Optica}},
  number       = {{3}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Quantum-limited detection of the arrival time and the carrier frequency of time-dependent signals}}},
  doi          = {{10.1364/optica.579459}},
  volume       = {{13}},
  year         = {{2026}},
}

@article{63451,
  abstract     = {{<jats:p>Superconducting nanowire single-photon detectors (SNSPDs) can enable photon-number resolution (PNR) based on accurate measurements of the detector’s response time to few-photon optical pulses. In this work, we investigate the impact of the optical pulse shape and duration on the accuracy of this method. We find that Gaussian temporal pulse shapes yield cleaner arrival-time histograms and, thus, more accurate PNR, compared to bandpass-filtered pulses of equal bandwidth. For low system jitter and an optical pulse duration comparable to the other jitter contributions, photon numbers can be discriminated in our system with a commercial SNSPD. At 60 ps optical pulse duration, photon-number discrimination is significantly reduced. Furthermore, we highlight the importance of using the correct arrival-time histogram model when analyzing photon-number assignment. Using exponentially modified Gaussian distributions, instead of the commonly used Gaussian distributions, we can more accurately determine photon-number misidentification probabilities. Finally, we reconstruct the positive operator-valued measures of the detector, revealing sharp features that indicate the intrinsic PNR capabilities.</jats:p>}},
  author       = {{Schapeler, Timon and Mischke, Isabell and Schlue, Fabian and Stefszky, Michael and Brecht, Benjamin and Silberhorn, Christine and Bartley, Tim}},
  issn         = {{2835-0103}},
  journal      = {{APL Quantum}},
  number       = {{1}},
  publisher    = {{AIP Publishing}},
  title        = {{{Practical considerations for assignment of photon numbers with SNSPDs}}},
  doi          = {{10.1063/5.0304127}},
  volume       = {{3}},
  year         = {{2026}},
}

@article{65095,
  abstract     = {{<jats:p>
                    We provide experimental validation of tight entropic uncertainty relations for the Shannon entropies of observables with mutually unbiased eigenstates in high dimensions. In particular, we address the cases of dimensions
                    <a:math xmlns:a="http://www.w3.org/1998/Math/MathML">
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                        <a:mi>d</a:mi>
                        <a:mo>=</a:mo>
                        <a:mn>3</a:mn>
                      </a:mrow>
                    </a:math>
                    , 4, and 5 and consider from 2 to
                    <b:math xmlns:b="http://www.w3.org/1998/Math/MathML">
                      <b:mrow>
                        <b:mi>d</b:mi>
                        <b:mo>+</b:mo>
                        <b:mn>1</b:mn>
                      </b:mrow>
                    </b:math>
                    mutually unbiased bases. The experiment is based on pulsed frequency bins measured with a multioutput quantum pulse gate, which can perform projective measurements on a complete high-dimensional basis in the time-frequency domain. Our results fit the theoretical predictions: the bound on the sum of the entropies is never violated and is saturated by the states that minimize the uncertainty relations.
                  </jats:p>}},
  author       = {{Serino, Laura Maria and Chesi, Giovanni and Brecht, Benjamin and Maccone, Lorenzo and Macchiavello, Chiara and Silberhorn, Christine}},
  issn         = {{2469-9926}},
  journal      = {{Physical Review A}},
  number       = {{3}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Experimental entropic uncertainty relations in dimensions three to five}}},
  doi          = {{10.1103/f6c4-jtlc}},
  volume       = {{113}},
  year         = {{2026}},
}

@article{63734,
  abstract     = {{Quantum dots (QDs) are a promising source of single photons mainly due to their on-demand operation. However, their emission wavelength depends on their size and immediate surroundings in the solid-state environment. By applying a serrodyne electro-optic phase modulation, we achieve a spectral shift up to 0.01 nm (3.5 GHz) while preserving the purity and indistinguishability of the photons. This method provides an efficient and scalable approach for tuning the emission wavelength of QDs without relying on nonlinear frequency mixing or probabilistic processes. Our results show that the electro-optic phase modulation enables stable and tunable spectral shifts, making it suitable for applications such as quantum communication, quantum key distribution, and primarily integrating remote quantum dot sources into large-scale quantum networks.}},
  author       = {{Kapoor, Sanjay and Rodek, Aleksander and Mikołajczyk, Michał and Szuniewicz, Jerzy and Sośnicki, Filip Maksymilian and Kazimierczuk, Tomasz and Kossacki, Piotr and Karpiński, Michał}},
  issn         = {{2192-8614}},
  journal      = {{Nanophotonics}},
  number       = {{11}},
  pages        = {{1775--1782}},
  publisher    = {{Walter de Gruyter GmbH}},
  title        = {{{Electro-optic frequency shift of single photons from a quantum dot}}},
  doi          = {{10.1515/nanoph-2024-0550}},
  volume       = {{14}},
  year         = {{2025}},
}

@article{63732,
  abstract     = {{Time lenses have been recognized as crucial components for manipulating ultrafast optical pulses in various applications, from ultrafast spectroscopy to the interfacing of optical quantum systems. A time lens is characterized by its chirp rate, which determines the focusing strength of the time lens, and accurate knowledge of this chirp is critical for precise dispersion compensation and minimizing aberrations. Here, we introduce a tunable time aperture model for sinusoidal time lenses that provides a more accurate estimate of the effective chirp rate without modifying the device. We derive a closed-form expression for the maximum phase error and show how it depends on the time aperture. We experimentally demonstrate a 1.6-fold improvement in spectral bandwidth compression of Gaussian pulses compared to the conventional approach. Our framework offers a practical tool for designing efficient temporal optical systems, benefiting applications in both classical and quantum optics where accurate spectro-temporal shaping is essential.}},
  author       = {{Kapoor, Sanjay and Sośnicki, Filip Maksymilian and Karpiński, Michał}},
  issn         = {{2378-0967}},
  journal      = {{APL Photonics}},
  number       = {{9}},
  publisher    = {{AIP Publishing}},
  title        = {{{Aberration-optimized electro-optic time lens model using a tunable aperture}}},
  doi          = {{10.1063/5.0270904}},
  volume       = {{10}},
  year         = {{2025}},
}

@article{59069,
  abstract     = {{<jats:p>Stable and bright single photon sources are key components for future quantum applications. A simple fabrication method is an important requirement for such sources. Here, we present a single photon source based on diced ridge waveguides in titanium indiffused LiNbO<jats:sub>3</jats:sub>. These waveguides can be easily fabricated by combining planar titanium in-diffusion without lithographic patterning and easy-to-handle precision dicing. Such devices have the potential to generate high single photon rates because ridge structures are typically less prone to the photorefractive effect. We achieve waveguide propagation losses &lt;0.4dBcm and a SHG conversion efficiency of about 81%Wcm<jats:sup>2</jats:sup>. Harnessing a type-0 SPDC process to generate 1550 nm photons, we obtain a SPDC brightness of 3⋅10<jats:sup>5</jats:sup>1s⋅mW⋅nm, with a heralding efficiency of <jats:italic>η</jats:italic><jats:sub>h</jats:sub>=45% (<jats:italic>η</jats:italic><jats:sub>h,wg</jats:sub>=77.5% for the waveguide itself excluded setup losses) and a heralded second-order correlation function of <jats:italic>g</jats:italic><jats:sub>h</jats:sub><jats:sup>2</jats:sup>(0)&lt;0.003 at low pump powers.</jats:p>}},
  author       = {{Kießler, Christian and Kirsch, Michelle and Lengeling, Sebastian and Herrmann, Harald and Silberhorn, Christine}},
  issn         = {{2770-0208}},
  journal      = {{Optics Continuum}},
  number       = {{3}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{SPDC single-photon source in Ti-indiffused diced ridge LiNbO<sub>3</sub> waveguides}}},
  doi          = {{10.1364/optcon.557439}},
  volume       = {{4}},
  year         = {{2025}},
}

@article{59276,
  abstract     = {{Stress plays a crucial role in thin films and layered systems, and thus significantly influences the material's electrical, mechanical and (nonlinear) optical responses. Despite lithium niobate's wide applicability as a nonlinear optical material, the impact of mechanical stress on its nonlinear optical properties is not well characterized. In this work, we systematically study both experimentally and theoretically, the nonlinear optical responses of thin film lithium niobate (TFLN) single crystals. Compressive and tensile stress is applied in our experiment using a piezodriven strain cell. We then record the second-harmonic-generated (SHG) response in back-reflection geometry, and compare these results to theoretical modeling using density functional theory (DFT). Both methods consistently reveal that uniaxial stress induces changes of the nonlinear optical susceptibility of certain tensor elements on the order of up to 1 pm/(V GPa). The exact value depends on the tensor element that is addressed in our SHG analysis, on the crystal orientation, and also whether using compressive or tensile stresses. Furthermore, a lowering of the crystal symmetry when applying stress along the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>x</a:mi></a:math> or <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mi>y</b:mi></b:math> crystallographic axes is observed by the appearance of new nonlinear optical tensor elements within the strained crystals.}},
  author       = {{Pionteck, Mike N. and Roeper, Matthias and Koppitz, Boris and Seddon, Samuel D. and Rüsing, Michael and Padberg, Laura and Eigner, Christof and Silberhorn, Christine and Sanna, Simone and Eng, Lukas M.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{6}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Second-order nonlinear piezo-optic properties of single crystal lithium niobate thin films}}},
  doi          = {{10.1103/physrevb.111.064109}},
  volume       = {{111}},
  year         = {{2025}},
}

@article{61338,
  abstract     = {{Conductive ferroelectric domain walls (DWs) represent a promising topical system for the development of nanoelectronic components and device sensors to be operational at elevated temperatures. DWs show very different properties as compared to their hosting bulk crystal, in particular with respect to the high local electrical conductivity. The objective of this work is to demonstrate DW conductivity up to temperatures as high as 400 °C which extends previous studies significantly. Experimental investigation of the DW conductivity of charged, inclined DWs is performed using 5 mol % MgO-doped lithium niobate single crystals. Current–voltage (  ) curves are determined by DC electrometer measurements and impedance spectroscopy and found to be identical. Moreover, impedance spectroscopy enables to recognize artifacts such as damaged electrodes. Temperature dependent measurements over repeated heating cycles reveal two distinct thermal activation energies for a given DW, with the higher of the activation energies only measured at higher temperatures. Depending on the specific sample, the higher activation energy is found above 160 °C to 230 °C. This suggests, in turn, that more than one type of defect/polaron is involved, and that the dominant transport mechanism changes with increasing temperature. First principles atomistic modeling suggests that the conductivity of inclined domain walls cannot be solely explained by the formation of a 2D carrier gas and must be supported by hopping processes. This holds true even at temperatures as high as 400 °C. Our investigations underline the potential to extend DW current based nanoelectronic and sensor applications even into the so-far unexplored temperature range up to 400 °C.}},
  author       = {{Wulfmeier, Hendrik and Yakhnevych, Uliana and Boekhoff, Cornelius and Diima, Allan and Kunzner, Marlo and Verhoff, Leonard M. and Paul, Jonas and Ratzenberger, Julius and Beyreuther, Elke and Gössel, Joshua and Kiseleva, Iuliia and Rüsing, Michael and Sanna, Simone and Eng, Lukas M. and Fritze, Holger}},
  issn         = {{0167-2738}},
  journal      = {{Solid State Ionics}},
  publisher    = {{Elsevier BV}},
  title        = {{{Demonstration of domain wall current in MgO-doped lithium niobate single crystals up to 400°C}}},
  doi          = {{10.1016/j.ssi.2025.116949}},
  volume       = {{429}},
  year         = {{2025}},
}

@misc{62639,
  author       = {{Kruse, Stephan and Silberhorn, Christine and Brecht, Benjamin and Schwabe, Tobias}},
  title        = {{{Optisch basierter Digital-Analog-Umsetzer}}},
  year         = {{2025}},
}

@article{62749,
  abstract     = {{Coherent Raman scattering techniques as coherent anti-Stokes Raman scattering (CARS), offer significant advantages in terms of pixel dwell times and speed as compared to spontaneous Raman scattering for investigations of crystalline materials. However, the spectral information in CARS is often hampered by the presence of a nonresonant contribution to the scattering process that shifts and distorts the Raman peaks. In this work, we apply a method to obtain nonresonant background-free spectra based on time-delayed, broadband CARS (TD-BCARS) using an intrapulse excitation scheme. In particular, this method can measure the phononic dephasing times across the full phonon spectrum at once. We test the methodology on amorphous SiO2 (glass), which is used to characterize the setup-specific and material-independent response times, and then apply TD-BCARS to the analysis of single crystals of diamond and ferroelectrics of potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA). For diamond, we determine a dephasing time of 𝜏=7.81 ps for the single 𝑠⁢𝑝3 peak.}},
  author       = {{Hempel, F. and Rüsing, Michael and Vernuccio, F. and Spychala, K. J. and Buschbeck, R. and Cerullo, G. and Polli, D. and Eng, L. M.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{22}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Phonon dephasing times determined with time-delayed broadband coherent anti-Stokes Raman scattering}}},
  doi          = {{10.1103/1ctr-csjy}},
  volume       = {{112}},
  year         = {{2025}},
}

@article{62911,
  abstract     = {{<jats:p>In this paper, we theoretically study the spectral and temporal properties of pulsed spontaneous parametric down-conversion (SPDC) generated in lossy waveguides. Our theoretical approach is based on the formalism of Gaussian states and the Langevin equation, which is elaborated for weak parametric down-conversion and photon-number-unresolved click detection. Using the example of frequency-degenerate type-II SPDC generated under the pump-idler group-velocity-matching condition, we show how the joint-spectral intensity, mode structure, normalized second-order correlation function, and Hong-Ou-Mandel interference pattern depend on internal losses of the SPDC process. We found that the joint-spectral intensity is almost insensitive to internal losses, while the second-order correlation function shows a strong dependence on them, being different for the signal and idler beams in the presence of internal losses. Based on the sensitivity of the normalized second-order correlation function, we show how its measurement can be used to experimentally determine internal losses.</jats:p>}},
  author       = {{Kopylov, Denis A. and Stefszky, Michael and Meier, Torsten and Silberhorn, Christine and Sharapova, Polina R.}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{3}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Spectral and temporal properties of type-II parametric down-conversion: The impact of losses during state generation}}},
  doi          = {{10.1103/zp72-7qwl}},
  volume       = {{7}},
  year         = {{2025}},
}

@article{62269,
  abstract     = {{The titanium in-diffused lithium niobate waveguide platform is well-established for reliable prototyping and packaging of many quantum photonic components at room temperature. Nevertheless, compatibility with certain quantum light sources and superconducting detectors requires operation under cryogenic conditions. We characterize alterations in phase-matching and mode guiding of a non-degenerate spontaneous parametric down-conversion process emitting around 1556 nm and 950 nm, under cryogenic conditions. Despite the effects of pyroelectricity and photorefraction, the spectral properties match our theoretical model. Nevertheless, these effects cause small but significant variations within and between cooling cycles. These measurements provide a first benchmark against which other nonlinear photonic integration platforms, such as thin-film lithium niobate, can be compared.}},
  author       = {{Lange, Nina Amelie and Lengeling, Sebastian and Mues, Philipp and Quiring, Viktor and Ridder, Werner and Eigner, Christof and Herrmann, Harald and Silberhorn, Christine and Bartley, Tim}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  number       = {{24}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Widely non-degenerate nonlinear frequency conversion in cryogenic titanium in-diffused lithium niobate waveguides}}},
  doi          = {{10.1364/oe.578108}},
  volume       = {{33}},
  year         = {{2025}},
}

@article{63192,
  abstract     = {{Lithium niobate (LiNbO3) is a widely used material with several desirable physical properties, such as high second-order nonlinear optical and strong electro-optical effects. Thus LiNbO3 is used for various applications such as electro-optic modulation or nonlinear frequency conversion and mixing. But LiNbO3 also exhibits a strong photorefractive effect, which limits the intensity of the optical fields involved. Various approaches to reduce the photorefractive effect have been investigated, such as increasing the temperature, doping the crystal or using different waveguide designs in LiNbO3. Here, we present an analysis of the approach to increase the photorefractive damage threshold by using different waveguide designs. Contrary to previous claims and investigations, our SHG measurements revealed no significant difference in resistance to photorefractive damage when comparing conventional Ti-doped channel waveguides and Ti-doped diced ridge waveguides in LiNbO3. Furthermore, we have investigated the effect of photorefractive cleaning and curing using a light field at 532 nm. Here, we observe a reduction in the photorefractive effect at room temperature during and after SHG measurements, which is an easy alternative to conventional approaches.}},
  author       = {{Kirsch, Michelle and Kießler, Christian and Lengeling, Sebastian and Stefszky, Michael and Eigner, Christof and Herrmann, Harald and Silberhorn, Christine}},
  issn         = {{0030-3992}},
  journal      = {{Optics & Laser Technology}},
  publisher    = {{Elsevier BV}},
  title        = {{{Photorefraction and in-situ optical cleaning in various types of LiNbO3 waveguides}}},
  doi          = {{10.1016/j.optlastec.2025.114260}},
  volume       = {{193}},
  year         = {{2025}},
}

@article{63091,
  abstract     = {{We present the design and characterization of a guided-wave, bright, and highly frequency non-degenerate parametric down-conversion (PDC) source in thin-film lithium niobate. The source generates photon pairs with wavelengths of 815 nm and 1550 nm, linking the visible wavelength regime with telecommunication wavelengths. We confirm the high quality of the generated single photons by determining a value for the heralded second-order correlation function as low as g_h^(2)=(6.7+/-1.1)*10^8-3). Furthermore, we achieve a high spectral brightness of 0.44·10pairs/(smWGHz) which is two orders of magnitude higher than sources based on weakly guiding waveguides. The shape of the PDC spectrum and the strong agreement between the effective and nominal bandwidth highlight our high fabrication quality of periodically poled waveguides. The good agreement between the measured and simulated spectral characteristics of our source demonstrates our excellent understanding of the PDC process. Our result is a valuable step towards practical and scalable quantum communication networks as well as photonic quantum computing.}},
  author       = {{Babel, Silia and Bollmers, Laura and Roeder, Franz and Ridder, Werner and Golla, Christian and Köthemann, Ronja and Reineke, Bernhard and Herrmann, Harald and Brecht, Benjamin and Eigner, Christof and Padberg, Laura and Silberhorn, Christine}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  number       = {{25}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Ultrabright, two-color photon pair source based on thin-film lithium niobate for bridging visible and telecom wavelengths}}},
  doi          = {{10.1364/oe.571605}},
  volume       = {{33}},
  year         = {{2025}},
}

@article{62713,
  abstract     = {{Periodically poled thin-film lithium niobate (TFLN) crystals are the fundamental building block for highly-efficient quantum light sources and frequency converters. The efficiency of these devices is strongly dependent on the interaction length between the light and the nonlinear material, scaling quadratically with this parameter. Nevertheless, the fabrication of long, continuously poled areas in TFLN remains challenging, the length of continuously poled areas rarely exceeds 10 mm. In this work, we demonstrate a significant progress in this field achieving the periodic poling of continuous poled areas of 70 mm length with a 3 μm poling period and a close to 50 % duty cycle. We compare two poling electrode design approaches to fabricate long, continuous poled areas. The first approach involves the poling of a single, continuous 70 mm long electrode. The second utilize a segmented approach including the poling of more than 20 individual sections forming together a 70 mm long poling area with no stitching errors. While the continuous electrode allows for faster fabrication, the segmented approach allows to individually optimize the poling resulting in less duty cycle variation. A detailed analysis of the periodic poling results reveals that the results of both are consistent with previously reported poling outcomes for shorter devices. Thus, we demonstrate wafer-scale periodic poling exceeding chiplet-size without any loss in the periodic poling quality. Our work presents a key step towards highly-efficient, narrow-bandwidth and low-pump power nonlinear optical devices.}},
  author       = {{Bollmers, Laura and Spiegelberg, Noah and Rüsing, Michael and Eigner, Christof and Padberg, Laura and Silberhorn, Christine}},
  issn         = {{2192-8606}},
  journal      = {{Nanophotonics}},
  pages        = {{4761}},
  publisher    = {{Walter de Gruyter GmbH}},
  title        = {{{Segmented finger electrodes to optimize ultra-long continuous wafer-scale periodic poling in thin-film lithium niobate}}},
  doi          = {{10.1515/nanoph-2025-0461}},
  volume       = {{14}},
  year         = {{2025}},
}

@article{60566,
  author       = {{Bocchini, Adriana and Rüsing, Michael and Bollmers, Laura and Lengeling, Sebastian and Mues, Philipp and Padberg, Laura and Gerstmann, Uwe and Silberhorn, Christine and Eigner, Christof and Schmidt, Wolf Gero}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  number       = {{7}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Mg dopants in lithium niobate: Defect models and impact on domain inversion}}},
  doi          = {{10.1103/5wz1-bjyr}},
  volume       = {{9}},
  year         = {{2025}},
}

@article{63733,
  abstract     = {{<jats:p>We study a possibility of measuring the time-resolved second-order autocorrelation function of one of two beams generated in type-II parametric down-conversion by means of temporal magnification of this beam, bringing its correlation time from the picosecond to the nanosecond scale, which can be resolved by modern photodetectors. We show that such a measurement enables one to infer directly the degree of global coherence of that beam, which is linked by a simple relation to the number of modes characterizing the entanglement between the two generated beams. We illustrate the proposed method by an example of photon pairs generated in a periodically poled potassium titanyl phosphate (KTP) crystal with a symmetric group velocity matching for various durations of the pump pulse, resulting in different numbers of modes. Our theoretical model also shows that the magnified double-heralded autocorrelation function of one beam exhibits a local maximum around zero delay time, corresponding to photon bunching at a short time scale.</jats:p>}},
  author       = {{Horoshko, Dmitri B. and Srivastava, Shivang and Sośnicki, Filip Maksymilian and Mikołajczyk, Michał and Karpiński, Michał and Brecht, Benjamin and Kolobov, Mikhail I.}},
  issn         = {{2469-9926}},
  journal      = {{Physical Review A}},
  number       = {{2}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Time-resolved second-order autocorrelation function of parametric down-conversion}}},
  doi          = {{10.1103/7ckm-tm3r}},
  volume       = {{112}},
  year         = {{2025}},
}

@article{51156,
  abstract     = {{Ferroelectric domain wall (DW) conductivity (DWC) can be attributed to two separate mechanisms: (a) the injection/ejection of charge carriers across the Schottky barrier formed at the (metal-)electrode-DW junction and (b) the transport of those charge carriers along the DW. Current-voltage (I-U) characteristics, recorded at variable temperatures from LiNbO3 (LNO) DWs, are clearly able to differentiate between these two contributions. Practically, they allow us to directly quantify the physical parameters relevant to the two mechanisms (a) and (b) mentioned above. These are, for example, the resistance of the DW, the saturation current, the ideality factor, and the Schottky barrier height of the electrode-DW junction. Furthermore, the activation energies needed to initiate the thermally activated electronic transport along the DWs can be extracted. In addition, we show that electronic transport along LNO DWs can be elegantly viewed and interpreted in an adapted semiconductor picture based on a double-diode, double-resistor equivalent-circuit model, the R2D2 model. Finally, our R2D2 model was checked for its universality by successfully fitting the I-U curves of not only z-cut LNO bulk DWs, but equally of z-cut thin-film LNO DWs, and of x-cut thin-film DWs as reported in literature.}},
  author       = {{Zahn, Manuel and Beyreuther, Elke and Kiseleva, Iuliia and Lotfy, Ahmed Samir and McCluskey, Conor J. and Maguire, Jesi R. and Suna, Ahmet and Rüsing, Michael and Gregg, J. Marty and Eng, Lukas M.}},
  issn         = {{2331-7019}},
  journal      = {{Physical Review Applied}},
  keywords     = {{General Physics and Astronomy}},
  number       = {{2}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Equivalent-circuit model that quantitatively describes domain-wall conductivity in ferroelectric lithium }}},
  doi          = {{10.1103/physrevapplied.21.024007}},
  volume       = {{21}},
  year         = {{2024}},
}