@article{63048, title = {{{High-throughput antibody screening with high-quality factor nanophotonics and bioprinting}}}, doi = {{10.48550/ARXIV.2411.18557}}, year = {{2024}}, } @misc{63047, author = {{Güsken, Nicholas Alexander}}, title = {{{Schottky-barrier type infrared photodetector }}}, year = {{2024}}, } @article{63044, author = {{Hoessbacher, C. and Baeuerle, B. and Del Medico, N. and De Leo, E. and Güsken, Nicholas Alexander and Heni, W. and Langenbach, A. and Tedaldi, V.}}, issn = {{2732-4494}}, journal = {{IET Conference Proceedings}}, number = {{34}}, pages = {{1606--1608}}, publisher = {{Institution of Engineering and Technology (IET)}}, title = {{{Plasmonic modulators: bringing a new light to silicon}}}, doi = {{10.1049/icp.2023.2642}}, volume = {{2023}}, year = {{2024}}, } @article{63049, author = {{Güsken, Nicholas Alexander and Brongersma, Mark L.}}, issn = {{2791-1748}}, journal = {{Photonics Insights}}, number = {{4}}, publisher = {{Shanghai Institute of Optics and Fine Mechanics}}, title = {{{Electrifying the field of metasurface optics}}}, doi = {{10.3788/pi.2024.c08}}, volume = {{3}}, year = {{2024}}, } @article{53202, abstract = {{At large scales, quantum systems may become advantageous over their classical counterparts at performing certain tasks. Developing tools to analyze these systems at the relevant scales, in a manner consistent with quantum mechanics, is therefore critical to benchmarking performance and characterizing their operation. While classical computational approaches cannot perform like-for-like computations of quantum systems beyond a certain scale, classical high-performance computing (HPC) may nevertheless be useful for precisely these characterization and certification tasks. By developing open-source customized algorithms using high-performance computing, we perform quantum tomography on a megascale quantum photonic detector covering a Hilbert space of 106. This requires finding 108 elements of the matrix corresponding to the positive operator valued measure (POVM), the quantum description of the detector, and is achieved in minutes of computation time. Moreover, by exploiting the structure of the problem, we achieve highly efficient parallel scaling, paving the way for quantum objects up to a system size of 1012 elements to be reconstructed using this method. In general, this shows that a consistent quantum mechanical description of quantum phenomena is applicable at everyday scales. More concretely, this enables the reconstruction of large-scale quantum sources, processes and detectors used in computation and sampling tasks, which may be necessary to prove their nonclassical character or quantum computational advantage.}}, author = {{Schapeler, Timon and Schade, Robert and Lass, Michael and Plessl, Christian and Bartley, Tim}}, journal = {{Quantum Science and Technology}}, number = {{1}}, publisher = {{IOP Publishing}}, title = {{{Scalable quantum detector tomography by high-performance computing}}}, doi = {{10.1088/2058-9565/ad8511}}, volume = {{10}}, year = {{2024}}, } @article{63219, abstract = {{We introduce the framework of Bayesian relative belief that directly evaluates whether or not the experimental data at hand support a given hypothesis regarding a quantum system by directly comparing the prior and posterior probabilities for the hypothesis. In model-dimension certification tasks, we show that the relative-belief procedure typically chooses Hilbert spaces that are never smaller in dimension than those selected from optimizing a broad class of information criteria, including Akaike's criterion. As a concrete and focused exposition of this powerful evidence-based technique, we apply the relative-belief procedure to an important application: . In particular, just by comparing prior and posterior probabilities based on data, we demonstrate its capability of tracking multiphoton emissions using (realistically lossy) single-photon detectors in order to assess the actual quality of photon sources without making assumptions, thereby reliably safeguarding source integrity for general quantum-information and communication tasks with Bayesian reasoning. Finally, we discuss how relative belief can be exploited to carry out parametric model certification and estimate the total dimension of the quantum state for the combined (measured) physical and interacting external systems described by the Tavis-Cummings model. Published by the American Physical Society 2024 }}, author = {{Teo, Y. S. and Shringarpure, S. U. and Jeong, H. and Prasannan, Nidhin and Brecht, Benjamin and Silberhorn, Christine and Evans, M. and Mogilevtsev, D. and Sánchez-Soto, L. L.}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Relative-belief inference in quantum information theory}}}, doi = {{10.1103/physreva.110.012231}}, volume = {{110}}, year = {{2024}}, } @article{63216, abstract = {{The characterization of the complex spectral amplitude, that is, the spectrum and spectral phase, of single-photon-level light fields is a crucial capability for modern photonic quantum technologies. Since established pulse characterization techniques are not applicable at low intensities, alternative approaches are required. Here, we demonstrate the retrieval of the complex spectral amplitude of single-photon-level light pulses through measuring their chronocyclic Q −function. Our approach draws inspiration from quantum state tomography by exploiting the analogy between quadrature phase space and time-frequency phase space. In the experiment, we perform time-frequency projections with a quantum pulse gate (QPG), which directly yield the chronocyclic Q −function. We evaluate the complex spectral amplitude from the measured chronocyclic Q −function data with maximum likelihood estimation (MLE), which is the established technique for quantum state tomography. The MLE yields not only an unambigious estimate of the complex spectral amplitude of the state under test that does not require any a priori information, but also allows for, in principle, estimating the spectral-temporal coherence properties of the state. Our method accurately recovers features such as jumps in the spectral phase and is resistant against regions with zero spectral intensity, which makes it immediately beneficial for classical pulse characterization problems.}}, author = {{Bhattacharjee, Abhinandan and Folge, Patrick Fabian and Serino, Laura Maria and Řeháček, Jaroslav and Hradil, Zdeněk and Silberhorn, Christine and Brecht, Benjamin}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{3}}, publisher = {{Optica Publishing Group}}, title = {{{Pulse characterization at the single-photon level through chronocyclic Q-function measurements}}}, doi = {{10.1364/oe.540125}}, volume = {{33}}, year = {{2024}}, } @article{63220, abstract = {{Identifying a reasonably small Hilbert space that completely describes an unknown quantum state is crucial for efficient quantum information processing. We introduce a general dimension-certification protocol for both discrete and continuous variables that is fully evidence based, relying solely on the experimental data collected and no other unjustified assumptions whatsoever. Using the Bayesian concept of relative belief, we take the effective dimension of the state as the smallest one such that the posterior probability is larger than the prior, as dictated by the data. The posterior probabilities associated with the relative-belief ratios measure the strength of the evidence provide by these ratios so that we can assess whether there is weak or strong evidence in favor or against a particular dimension. Using experimental data from spectral-temporal and polarimetry measurements, we demonstrate how to correctly assign Bayesian plausible error bars for the obtained effective dimensions. This makes relative belief a conservative and easy-to-use model-selection method for any experiment. Published by the American Physical Society 2024 }}, author = {{Teo, Y. S. and Shringarpure, S. U. and Jeong, H. and Prasannan, Nidhin and Brecht, Benjamin and Silberhorn, Christine and Evans, M. and Mogilevtsev, D. and Sánchez-Soto, L. L.}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, number = {{5}}, publisher = {{American Physical Society (APS)}}, title = {{{Evidence-Based Certification of Quantum Dimensions}}}, doi = {{10.1103/physrevlett.133.050204}}, volume = {{133}}, year = {{2024}}, } @article{54288, abstract = {{The ability to apply user-chosen large-scale unitary operations with high fidelity to a quantum state is key to realizing future photonic quantum technologies. Here, we realize the implementation of programmable unitary operations on up to 64 frequency-bin modes. To benchmark the performance of our system, we probe different quantum walk unitary operations, in particular, Grover walks on four-dimensional hypercubes with similarities exceeding 95% and quantum walks with 400 steps on circles and finite lines with similarities of 98%. Our results open a path toward implementing high-quality unitary operations, which can form the basis for applications in complex tasks, such as Gaussian boson sampling. Published by the American Physical Society 2024 }}, author = {{De, Syamsundar and Ansari, Vahid and Sperling, Jan and Barkhofen, Sonja and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Realization of high-fidelity unitary operations on up to 64 frequency bins}}}, doi = {{10.1103/physrevresearch.6.l022040}}, volume = {{6}}, year = {{2024}}, } @article{63218, abstract = {{Linear optical quantum networks, consisting of a quantum input state and a multiport interferometer, are an important building block for many quantum technological concepts, e.g., Gaussian boson sampling. Here, we propose the implementation of such networks based on frequency conversion by utilizing a so-called multioutput quantum pulse gate (MQPG). This approach allows the resource-efficient and therefore scalable implementation of frequency-bin-based, fully programmable interferometers in a single spatial and polarization mode. Quantum input states for this network can be provided by utilizing the strong frequency entanglement of a type-0 parametric down-conversion (PDC) source. Here, we develop a theoretical framework to describe linear networks based on an MQPG and PDC and utilize it to investigate the limits and scalabilty of our approach. Published by the American Physical Society 2024 }}, author = {{Folge, Patrick Fabian and Stefszky, Michael and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{2691-3399}}, journal = {{PRX Quantum}}, number = {{4}}, publisher = {{American Physical Society (APS)}}, title = {{{A Framework for Fully Programmable Frequency-Encoded Quantum Networks Harnessing Multioutput Quantum Pulse Gates}}}, doi = {{10.1103/prxquantum.5.040329}}, volume = {{5}}, year = {{2024}}, } @article{63217, abstract = {{We demonstrate a high-dimensional mode-sorter for single photons based on a multi-output quantum pulse gate, which we can program to switch between different temporal-mode encodings including pulse modes, frequency bins, time bins, and their superpositions. This device can facilitate practical realizations of quantum information applications such as high-dimensional quantum key distribution and thus enables secure communication with enhanced information capacity. We characterize the mode-sorter through a detector tomography in 3 and 5 dimensions and find a fidelity up to 0.958 ± 0.030 at the single-photon level.}}, author = {{Serino, Laura Maria and Eigner, Christof and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{3}}, publisher = {{Optica Publishing Group}}, title = {{{Programmable time-frequency mode-sorting of single photons with a multi-output quantum pulse gate}}}, doi = {{10.1364/oe.544206}}, volume = {{33}}, year = {{2024}}, } @article{50840, abstract = {{Superconducting nanowire single-photon detectors (SNSPDs) have been widely used to study the discrete nature of quantum states of light in the form of photon-counting experiments. We show that SNSPDs can also be used to study continuous variables of optical quantum states by performing homodyne detection at a bandwidth of 400 kHz. By measuring the interference of a continuous-wave field of a local oscillator with the field of the vacuum state using two SNSPDs, we show that the variance of the difference in count rates is linearly proportional to the photon flux of the local oscillator over almost five orders of magnitude. The resulting shot-noise clearance of (46.0 ± 1.1) dB is the highest reported clearance for a balanced optical homodyne detector, demonstrating their potential for measuring highly squeezed states in the continuous-wave regime. In addition, we measured a CMRR = 22.4 dB. From the joint click counting statistics, we also measure the phase-dependent quadrature of a weak coherent state to demonstrate our device’s functionality as a homodyne detector.}}, author = {{Protte, Maximilian and Schapeler, Timon and Sperling, Jan and Bartley, Tim}}, issn = {{2837-6714}}, journal = {{Optica Quantum}}, number = {{1}}, publisher = {{Optica Publishing Group}}, title = {{{Low-noise balanced homodyne detection with superconducting nanowire single-photon detectors}}}, doi = {{10.1364/opticaq.502201}}, volume = {{2}}, year = {{2024}}, } @article{54815, abstract = {{Broadband quantum light is a vital resource for quantum metrology and spectroscopy applications such as quantum optical coherence tomography or entangled two photon absorption. For entangled two photon absorption in particular, very high photon flux combined with high time-frequency entanglement is crucial for observing a signal. So far these conditions could be met by using high power lasers driving degenerate, type 0 bulk-crystal spontaneous parametric down conversion (SPDC) sources. This naturally limits the available wavelength ranges and precludes deterministic splitting of the generated output photons. In this work we demonstrate an integrated two-colour SPDC source utilising a group-velocity matched lithium niobate waveguide, reaching both exceptional brightness 1.52⋅106pairssmWGHz and large bandwidth (7.8 THz FWHM) while pumped with a few mW of continuous wave (CW) laser light. By converting a narrow band pump to broadband pulses the created photon pairs show correlation times of Δτ ≈ 120 fs while maintaining the narrow bandwidth Δω p  ≪ 1 MHz of the CW pump light, yielding strong time-frequency entanglement. Furthermore our process can be adapted to a wide range of central wavelengths.}}, author = {{Pollmann, René and Roeder, Franz and Quiring, Victor and Ricken, Raimund and Eigner, Christof and Brecht, Benjamin and Silberhorn, Christine}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{14}}, publisher = {{Optica Publishing Group}}, title = {{{Integrated, bright broadband, two-colour parametric down-conversion source}}}, doi = {{10.1364/oe.522549}}, volume = {{32}}, year = {{2024}}, } @article{57862, abstract = {{The latest applications in ultrafast quantum metrology require bright, broadband bi-photon sources with one of the photons in the mid-infrared and the other in the visible to near infrared. However, existing sources based on bulk crystals are limited in brightness due to the short interaction length and only allow for limited dispersion engineering. Here, we present an integrated PDC source based on a Ti:LiNbO3 waveguide that generates broadband bi-photons with central wavelengths at 860 nm and 2800 nm. Their spectral bandwidth exceeds 25 THz and is achieved by simultaneous matching of the group velocities (GVs) and cancellation of GV dispersion for the signal and idler field. We provide an intuitive understanding of the process by studying our source’s behavior at different temperatures and pump wavelengths, which agrees well with simulations.}}, author = {{Roeder, Franz and Gnanavel, Abira and Pollmann, René and Brecht, Olga and Stefszky, Michael and Padberg, Laura and Eigner, Christof and Silberhorn, Christine and Brecht, Benjamin}}, issn = {{1367-2630}}, journal = {{New Journal of Physics}}, number = {{12}}, publisher = {{IOP Publishing}}, title = {{{Ultra-broadband non-degenerate guided-wave bi-photon source in the near and mid-infrared}}}, doi = {{10.1088/1367-2630/ad9f98}}, volume = {{26}}, year = {{2024}}, } @article{57028, abstract = {{Lithium niobate and lithium tantalate are among the most widespread materials for nonlinear, integrated photonics. Mixed crystals with arbitrary Nb–Ta ratios provide an additional degree of freedom to not only tune materials properties, such as the birefringence but also leverage the advantages of the singular compounds, for example, by combining the thermal stability of lithium tantalate with the larger nonlinear or piezoelectric constants of lithium niobate. Periodic poling allows to achieve phase-matching independent of waveguide geometry and is, therefore, one of the commonly used methods in integrated nonlinear optics. For mixed crystals, periodic poling has been challenging so far due to the lack of homogeneous, mono-domain crystals, which severely inhibit domain growth and nucleation. In this work, we investigate surface-near (<1μm depth) domain inversion on x-cut lithium niobate tantalate mixed crystals via electric field poling and lithographically structured electrodes. We find that naturally occurring head-to-head or tail-to-tail domain walls in the as-grown crystal inhibit domain inversion at a larger scale. However, periodic poling is possible if the gap size between the poling electrodes is of the same order of magnitude or smaller than the average size of naturally occurring domains. This work provides the basis for the nonlinear optical application of lithium niobate tantalate mixed crystals.}}, author = {{Bollmers, Laura and Babai-Hemati, Tobias and Koppitz, Boris and Eigner, Christof and Padberg, Laura and Rüsing, Michael and Eng, Lukas M. and Silberhorn, Christine}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{15}}, publisher = {{AIP Publishing}}, title = {{{Surface-near domain engineering in multi-domain x-cut lithium niobate tantalate mixed crystals}}}, doi = {{10.1063/5.0210972}}, volume = {{125}}, year = {{2024}}, } @inproceedings{57107, author = {{Kress, Christian and Schwabe, Tobias and Mihaylov, Martin Miroslavov and Silberhorn, Christine and Scheytt, J. Christoph}}, location = {{Paderborn}}, title = {{{Integrated Pulse Generator for Photon Pair Generation using Lithium Niobate on Insulator Technology}}}, year = {{2024}}, } @inproceedings{57111, author = {{Mihaylov, Martin Miroslavov and Kress, Christian and Scheytt, J. Christoph}}, location = {{Paderborn}}, title = {{{Simulation and Optimization of Low-Loss Photonic Coupling Structures for TFLN Integrated Circuits for Quantum Applications}}}, year = {{2024}}, } @misc{57089, author = {{Kruse, Stephan and Brecht, Benjamin and Silberhorn, Christine and Serino, Laura Maria}}, title = {{{Quantenoptisch-unterstütztes Sende-/Empfangssystem}}}, year = {{2024}}, } @article{57743, author = {{Krishnaswamy, Suchitra and Schlue, Fabian and Ares, L. and Dyachuk, V. and Stefszky, Michael and Brecht, Benjamin and Silberhorn, Christine and Sperling, Jan}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Experimental retrieval of photon statistics from click detection}}}, doi = {{10.1103/physreva.110.023717}}, volume = {{110}}, year = {{2024}}, } @article{32097, author = {{Weich, Tobias and Guedes Bonthonneau, Yannick and Guillarmou, Colin}}, journal = {{Journal of Differential Geometry}}, pages = {{959--1026}}, title = {{{SRB Measures of Anosov Actions}}}, doi = {{ DOI: 10.4310/jdg/1729092452}}, volume = {{128}}, year = {{2024}}, }