A5036934564- Quantum Information and Cryptography
- Photonic and Optical Devices
- Quantum optics and atomic interactions
- Advanced Fiber Laser Technologies
- Photorefractive and Nonlinear Optics
- Quantum Mechanics and Applications
- Quantum Computing Algorithms and Architecture
- Laser-Matter Interactions and Applications
- Neural Networks and Reservoir Computing
- Mechanical and Optical Resonators
- Optical Network Technologies
- Advanced Optical Sensing Technologies
- Random lasers and scattering media
- Atomic and Subatomic Physics Research
- Quantum and electron transport phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Orbital Angular Momentum in Optics
- Advanced Fluorescence Microscopy Techniques
- Advanced Photonic Communication Systems
- Solid State Laser Technologies
- Spectroscopy and Quantum Chemical Studies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Topological Materials and Phenomena
- Semiconductor Lasers and Optical Devices
- Semiconductor Quantum Structures and Devices
Paderborn University
2016-2025
Quantum Technologies (Sweden)
2023
Laboratoire Kastler Brossel
2020
Quantum Group (United States)
2019
Max Planck Institute for the Science of Light
2007-2017
Max Planck Society
2008-2013
Institute for Solid State Physics and Optics
2011
Hungarian Academy of Sciences
2011
Czech Technical University in Prague
2011
Friedrich-Alexander-Universität Erlangen-Nürnberg
1999-2008
We present an experimental demonstration of heralded single photons prepared in pure quantum states from a parametric down-conversion source. It is shown that, through controlling the modal structure photon pair emission, one can generate pairs factorable and thence eliminate need for spectral filters multiple-source interference schemes. Indistinguishable were generated two independent spectrally engineered sources Hong-Ou-Mandel observed between them without filters. The measured...
We present the first robust implementation of a coined quantum walk over five steps using only passive optical elements. By employing fiber network loop we keep amount required resources constant as walker's position Hilbert space is increased. observed non-Gaussian distribution final position, thus characterizing faster spread photon wave packet in comparison to classical random walk. The realized for many different coin settings and initial states, opening way quantum-walk-based search algorithm.
Boson sampling has emerged as a tool to explore the advantages of quantum over classical computers it does not require universal control system, which favors current photonic experimental platforms. Here, we introduce Gaussian sampling, classically hard-to-solve problem that uses squeezed states nonclassical resource. We relate probability measure specific photon patterns from general state in Fock basis matrix function called Hafnian, answers last remaining question states. Based on this...
Here, There, Everywhere Random walks are a powerful mathematical method that can be used to simulate certain processes in biology, chemistry, or even the stock market. They present statistical for mapping possible routes take. Quantum expected able probe multiple paths simultaneously. have been demonstrated one-dimensional, straight-line, walks. Now, Schreiber et al. (p. 55 , published online 8 March) demonstrate an optical system quantum over two-dimensional system, thereby providing...
We investigate the impact of decoherence and static disorder on dynamics quantum particles moving in a periodic lattice. Our experiment relies photonic implementation one-dimensional walk. The pure evolution is characterized by ballistic spread photon's wave packet along 28 steps. By applying controlled time-dependent operations we simulate three different environmental influences system, resulting fast spread, diffusive classical walk, first Anderson localization discrete walk architecture.
Optical metasurfaces open new avenues for precise wavefront control of light integrated quantum technology. Here, we demonstrate a hybrid photonic system that is capable to entangle and disentangle two-photon spin states at dielectric metasurface. By interfering single-photon pairs nanostructured metasurface, path-entangled NOON state with circular polarization generated exhibits HOM interference visibility 86 $\pm$ 4%. Furthermore, nonclassicality phase sensitivity in metasurface-based...
Since the development of boson sampling, there has been a quest to construct more efficient and experimentally feasible protocols test computational complexity sampling from photonic states. In this paper, we interpret extend results presented previously [Phys. Rev. Lett. 119, 170501 (2017)]. We derive an expression that relates probability measure specific photon output pattern Gaussian state Hafnian matrix function use it design protocol. Then, discuss advantages protocol relative other...
We review the rapid recent progress in single-photon sources based on multiplexing multiple probabilistic photon-creation events. Such allows higher probabilities and lower contamination from higher-order photon states. study requirements for multiplexed compare various approaches to using different degrees of freedom.
Conventional spectroscopy uses classical light to detect matter properties through the variation of its response with frequencies or time delays.Quantum opens up new avenues for by utilizing parameters quantum state as novel control knobs and photon statistics coupling matter.This Roadmap article focuses on using a powerful sensing spectroscopic tool reveal information about complex molecules that is not accessible light.It aims at bridging optics communities which normally have opposite...
We demonstrate that secure quantum key distribution systems based on continuous variable implementations can operate beyond the apparent 3 dB loss limit is implied by beam splitting attack. The was established for standard minimum uncertainty states such as coherent states. show that, an appropriate postselection mechanism, we enter a region where Eve's knowledge Alice's falls behind information shared between Alice and Bob, even in presence of substantial losses.
We report on the generation of a continuous variable Einstein-Podolsky-Rosen (EPR) entanglement using an optical fiber interferometer. The Kerr nonlinearity in is exploited for two independent squeezed beams. These interfere at beam splitter and EPR obtained between output correlation amplitude (phase) quadratures measured to be 4.0+/-0.2 (4.0+/-0.4) dB below quantum noise limit. sum criterion these squeezing variances 0.80+/-0.03<2 verifies nonseparability state. product inferred...
We report the development of a photon-number-resolving detector based on fiber-optical setup and pair standard avalanche photodiodes. The is capable resolving individual photon numbers operates well-known principle by which single-mode input state split into large number (eight) output modes. reconstruct statistics weak coherent light from experimental data show that there high probability inferring measurement detection events single run.
A concept of polarization entanglement for continuous variables is introduced. For this purpose the Stokes-parameter operators and associated Poincar\'e sphere, which describe quantum-optical properties light, are defined their basic reviewed. The general features Stokes illustrated by evaluation means variances a range simple states. Some examples show squeezing, in one or more parameters smaller than coherent-state value. main object paper application these concepts to bright squeezed...
We report the realization of a bright ultrafast two-mode squeezer based on type II parametric downconversion (PDC) in periodically poled $\mathrm{KTiOPO_4}$ (PP-KTP) waveguides. It produces pulsed squeezed vacuum state: photon-number entangled pair truly single-mode pulses or, terms continuous variables quantum optics, pulsed, single mode Einstein-Podolsky-Rosen (EPR) state telecom regime. prove character our source by measuring its $g^{(2)}$ correlation function and demonstrate mean photon...
Field-orthogonal temporal modes of photonic quantum states provide a new framework for information science (QIS). They intrinsically span high-dimensional Hilbert space and lend themselves to integration into existing single-mode fiber communication networks. We show that the three main requirements construct valid QIS -- controlled generation resource states, targeted highly efficient manipulation their detection can be fulfilled with current technology. suggest implementations diverse...
We generate pulsed, two mode squeezed states in a single spatio-temporal with mean photon numbers up to 20. directly measure photon-number-correlations between the modes transition edge sensors 80 photons per mode. This corresponds roughly state-dimensionality of 6400. achieve detection efficiencies 64% technologically crucial telecom regime and demonstrate high quality our measurements by heralded nonclassical distributions 50 pulse calculated correlation functions 40th order.
Abstract Observables of quantum systems can possess either a discrete or continuous spectrum. For example, upon measurements the photon number light state, outcomes will result whereas light's quadrature amplitudes in outcomes. If one uses degree freedom system for encoding, processing detecting information, enters field continuous‐variable (CV) information processing. In this paper we review basic principles CV with main focus on recent developments field. We be addressing three stages...
Broadband multimode squeezers constitute a powerful quantum resource with promising potential for different applications in information technologies such as coding communication networks or simulations higher-dimensional systems. However, the characterization of large array that coexist single spatial mode is challenging. In this paper, we address problem and propose straightforward method determining number their respective squeezing strengths by using broadband correlation function...
We study light propagation in a photonic system that shows stepwise evolution discretized environment. It resembles discrete-time version of waveguide arrays or quantum walks. By introducing controlled photon losses to our experimental setup, we observe unexpected effects like subexponential energy decay and formation complex fractal patterns. This demonstrates the interplay linear losses, discreteness gradients leads genuinely new coherent phenomena classical optical experiments. Moreover,...
We experimentally measured higher order normalized correlation functions (NCF) of pulsed light with a time-multiplexing detector. demonstrate excellent performance our device by verifying unity valued NCF up to the eighth for coherent and factorial dependence pseudothermal light. applied measurement technique type-II parametric down-conversion source investigate mutual two-mode properties ascertain nonclassicality.
We introduce the concept of a quantum pulse gate (QPG), method for accessing intrinsic broadband spectral mode structure ultrafast states light. This can now be harnessed applications in information processing. propose an implementation PPLN waveguide, based on spectrally engineered sum frequency generation (SFG). It allows us to pick well-defined modes from multi-mode state interconversion at another frequency. By pulse-shaping bright SFG pump beam, different orthogonal addressed...