Explanipedia

Quasiprobabilities from incomplete and overcomplete measurements Open

Jan Sperling, Laura Ares, Elizabeth Agudelo · 2025

We discuss the (re-)construction of quasiprobability representations from generic measurements, including noisy ones. Based on the measurement under study, quasiprobabilities and the associated concept of nonclassicality are introduced. A …

Resource-efficient universal photonic processor based on time-multiplexed hybrid architectures Open

Laura Ares, Philip J. Held, Benjamin Brecht, Jan Sperling · 2025

For the ever-growing field of quantum information processing, large-scale, efficient multi-port interferometers serving as photonic processors are required. In this context, the suitability of quantum walks as the interferometric base for …

Sensitivity and Topology of Exceptional Rings in Nonlinear Non-Hermitian Planar Optical Microcavities Open

Jan Wingenbach, Laura Ares, Xuekai Ma, N. H. Kwong, Jan Sperling , et al. · 2025

Non-Hermitian systems hosting exceptional points (EPs) exhibit enhanced sensitivity and unconventional mode dynamics. Going beyond isolated EPs, here we report on the existence of exceptional rings (ERs) in planar optical resonators with s…

Multiphoton, multimode state classification for nonlinear optical circuits Open

Д.А. Копылов, Christian Offen, Laura Ares, Boris Wembe, Sina Ober‐Blöbaum , et al. · 2025

We introduce a new classification of multimode states with a fixed number of photons. This classification is based on the factorizability of homogeneous multivariate polynomials and is invariant under unitary transformations. The classes p…

Multiphoton, multimode state classification for nonlinear optical circuits Open

Denis A. Kopylov, Christian Offen, Laura Ares, Boris Wembe Moafo, Sina Ober‐Blöbaum , et al. · 2025

We introduce a new classification of multimode states with a fixed number of photons. This classification is based on the factorizability of homogeneous multivariate polynomials and is invariant under unitary transformations. The classes p…

Predetection squeezing as a resource for high-dimensional Bell-state measurements Open

Luca Bianchi, Carlo Marconi, Jan Sperling, Davide Bacco · 2025

Bell measurements, entailing the projection onto one of the Bell states, play a key role in quantum information and communication, where the outcome of a variety of protocols crucially depends on the success probability of such measurement…

Universal Topology of Exceptional Points in Nonlinear Non-Hermitian Systems Open

N. H. Kwong, Jan Wingenbach, Laura Ares, Jan Sperling, Xuekai Ma , et al. · 2025

Exceptional points (EPs) are non-Hermitian degeneracies where eigenvalues and eigenvectors coalesce, giving rise to unusual physical effects across scientific disciplines. The concept of EPs has recently been extended to nonlinear physical…

Separability Lindblad equation for dynamical open-system entanglement Open

Julien Pinske, Laura Ares, Benjamin H. Hinrichs, Martin Kolb, Jan Sperling · 2024

Providing entanglement for the design of quantum technologies in the presence of noise constitutes today's main challenge in quantum information science. A framework is required that assesses the build-up of entanglement in realistic setti…

Restricted Monte Carlo wave function method and Lindblad equation for identifying entangling open-quantum-system dynamics Open

Laura Ares, Julien Pinske, Benjamin H. Hinrichs, Martin Kolb, Jan Sperling · 2024

We develop an extension of the Monte Carlo wave function approach that unambiguously identifies dynamical entanglement in general composite, open systems. Our algorithm performs tangential projections onto the set of separable states, lead…

Pre-detection squeezing as a resource for high-dimensional Bell-state measurements Open

Luca Bianchi, Carlo Marconi, Jan Sperling, Davide Bacco · 2024

Bell measurements, entailing the projection onto one of the Bell states, play a key role in quantum information and communication, where the outcome of a variety of protocols crucially depends on the success probability of such measurement…

Entanglement between dependent degrees of freedom: Quasiparticle correlations Open

Franziska Barkhausen, Laura Ares, Stefan Schumacher, Jan Sperling · 2024

Common notions of entanglement are based on well-separated subsystems. However, obtaining such independent degrees of freedom is not always possible because of physical constraints. In this work, we explore the notion of entanglement in th…

Entangled quantum trajectories in relativistic systems Open

Yannick Noel Freitag, Julien Pinske, Jan Sperling · 2024

Quantum entanglement is a key resource for quantum technologies, including emerging ground-to-satellite quantum communication. In such a scenario, an important challenge to be overcome is to consider entanglement between two or more quantu…

3D Anderson localization of light in disordered systems of dielectric particles Open

Yevgen Grynko, Dustin Siebert, Jan Sperling, Jens Förstner · 2024

We present the results of full wave numerical simulations of light transmission by layers of irregular dielectric particles that demonstrate 3D Anderson localization of light in disordered uncorrelated discrete media. Our simulations show …

Experimental observation of topological quantum criticality Open

Sonja Barkhofen, Syamsundar De, Jan Sperling, Christine Silberhorn, Alexander Altland , et al. · 2024

We report on a photonic simulator of the critical state forming at the quantum phase transition between topologically distinct Anderson insulator phases. We observe a time-staggered profile in the circular photon polarization, which origin…

Experimental retrieval of photon statistics from click detection Open

Suchitra Krishnaswamy, Fabian Schule, Laura Ares, Vladyslav Dyachuk, Michael Stefszky , et al. · 2024

We utilize click-counting theory for the reconstruction of photon statistics.\nOur approach employs an analytic pseudo-inversion method to estimate photon\ncounts from measured click counts. A reconfigurable time-bin multiplexing,\nclick-c…

Quantum walks and entanglement in cavity networks Open

C. Di Fidio, Laura Ares, Jan Sperling · 2024

For harnessing the full potential of quantum phenomena, light-matter interfaces and complexly connected quantum networks are required, relying on the joint quantum operation of different physical platforms. In this work, we analyze the qua…

Photonic Entanglement and Polarization Nonclassicality: Two Manifestations, One Nature Open

Laura Ares, Nidhin Prasannan, Elizabeth Agudelo, Alfredo Luis, Benjamin Brecht , et al. · 2024

We demonstrate in theory and experiment the strict equivalence between nonclassical polarization and the entanglement of indistinguishable photons, thereby unifying these two phenomena that appear dissimilar at first sight. This allows us …

Realization of high-fidelity unitary operations on up to 64 frequency bins Open

Syamsundar De, Vahid Ansari, Jan Sperling, Sonja Barkhofen, Benjamin Brecht , et al. · 2024

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…

Unbreakable and breakable quantum censorship Open

Julien Pinske, Jan Sperling · 2024

A protocol for regulating the distribution of quantum information between\nmultiple parties is put forward. In order to prohibit the unrestricted\ndistribution of quantum-resource states in a public quantum network, agents can\napply a res…

3D Anderson localization of light in disordered systems of dielectric particles Open

Yevgen Grynko, Dustin Siebert, Jan Sperling, Jens Förstner · 2023

We present the results of full-wave numerical simulations of light transmission through layers of irregular dielectric particles, demonstrating three-dimensional Anderson localization of light in disordered, uncorrelated discrete media. Ou…

Low-noise balanced homodyne detection with superconducting nanowire single-photon detectors Open

Maximilian Protte, Timon Schapeler, Jan Sperling, Tim J. Bartley · 2023

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 va…

Certifying the Topology of Quantum Networks: Theory and Experiment Open

Lisa T. Weinbrenner, Nidhin Prasannan, Kiara Hansenne, Sophia Denker, Jan Sperling , et al. · 2023

Distributed quantum information in networks is paramount for global secure quantum communication. Moreover, it finds applications as a resource for relevant tasks, such as clock synchronization, magnetic field sensing, and blind quantum co…

Continuous-variable quantum optics and resource theory for ultrafast semiconductor spectroscopy [Invited] Open

Carolin Lüders, Franziska Barkhausen, Matthias Pukrop, Elena Rozas, Jan Sperling , et al. · 2023

This review examines the use of continuous-variable spectroscopy techniques for investigating quantum coherence and light-matter interactions in semiconductor systems with ultrafast dynamics. Special emphasis is placed on multichannel homo…

Continuous-variable quantum optics and resource theory for ultrafast semiconductor spectroscopy Open

Carolin Lüders, Franziska Barkhausen, Matthias Pukrop, Elena Rozas, Jan Sperling , et al. · 2023

In this review, we discuss the use of continuous variable spectroscopy techniques for investigating quantum coherence and light-matter interactions in semiconductor systems with ultrafast dynamics. We focus on multichannel homodyne detecti…

Lossy SU(1,1) interferometers in the single-photon-pair regime Open

Matteo Santandrea, Kai-Hong Luo, Michael Stefszky, Jan Sperling, Hartmut Herrmann , et al. · 2023

The success of quantum technologies is intimately connected to the possibility of using them in real-world applications. This requires the system to be comprehensively modeled including various relevant experimental parameters. To this aim…

Data for: Tracking quantum coherence in polariton condensates with time-resolved tomography Open

Carolin Lüders, Matthias Pukrop, Franziska Barkhausen, Elena Rozas, Christian Schneider , et al. · 2023

Data for publication C. Lüders, M. Pukrop, F. Barkhausen, E. Rozas, C. Schneider, S. Höfling, J. Sperling, S. Schumacher, and M. Aßmann, Tracking quantum coherence in polariton condensates with time-resolved tomography, submitted. arXiv pr…

Data for: Tracking quantum coherence in polariton condensates with time-resolved tomography Open

Carolin Lüders, Matthias Pukrop, Franziska Barkhausen, Elena Rozas, Christian Schneider , et al. · 2023

Data for publication C. Lüders, M. Pukrop, F. Barkhausen, E. Rozas, C. Schneider, S. Höfling, J. Sperling, S. Schumacher, and M. Aßmann, Tracking quantum coherence in polariton condensates with time-resolved tomography, submitted. arXiv pr…

Experimental Observation of Topological Quantum Criticality Open

Sonja Barkhofen, Syamsundar De, Jan Sperling, Christine Silberhorn, Alexander Altland , et al. · 2023

We report on the observation of quantum criticality forming at the transition point between topological Anderson insulator phases in a one-dimensional photonic quantum walk with spin. The walker's probability distribution reveals a time-st…

Data for: Quantifying Quantum Coherence in Polariton Condensates Open

Carolin Lüders, Matthias Pukrop, Elena Rozas, Christian Schneider, Sven Höfling , et al. · 2023

Data for the publication C. Lüders, M. Pukrop, E. Rozas, C. Schneider, S. Höfling, J. Sperling, S. Schumacher, and M. Aßmann, Quantifying Quantum Coherence in Polariton Condensates, PRX Quantum, 2(3), 030320 (2021). We theoretically and ex…

Data for: Quantifying Quantum Coherence in Polariton Condensates Open

Carolin Lüders, Matthias Pukrop, Elena Rozas, Christian Schneider, Sven Höfling , et al. · 2023

Data for the publication C. Lüders, M. Pukrop, E. Rozas, C. Schneider, S. Höfling, J. Sperling, S. Schumacher, and M. Aßmann, Quantifying Quantum Coherence in Polariton Condensates, PRX Quantum, 2(3), 030320 (2021). We theoretically and ex…

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