7,754 research outputs found
Anmerkung zum Urteil des Bundesarbeitsgerichts vom 9.4.1991 - 1 AZR 488/90 - Verhältnis von Kollektiv- und Individualstreitigkeiten im Betriebsverfassungsrecht [Urteilsanmerkung]
No full textUrteilsanmerkung [Verhältnis von Kollektiv- u. Individualstreitigkeiten im Betriebsverfassungsrecht] / Wilhelm Dütz ; Stefan Rotter. - In: Entscheidungssammlung zum Arbeitsrecht. § 18 BetrVG 1972 (7, 1993
Blackbody radiation and the Weyl law in disordered media
No full textIn my talk, I will discuss an interesting property of blackbody radation when it propagates through complex media, such as disordered materials. As it turns out, the average time spent by the radiation in such a system–or, equivalently, its average path length–is entirely independent of whether the system is strongly disordered (and therefore opaque) or very weakly disordered (and therefore transparent). This property is linked to the so-called "Weyl law", that was discovered in 1911 by Hermann Weyl and allows one to estimate the density of states of a system just based on its geometrical parameters. After introducing this "path length invariance" [1] and its experimental implementations [2,3], I will show how these insights can be connected to information theory [4] and to the forces of the quantum vacuum [5].
[1] R. Pierrat, P. Ambichl, S. Gigan, A. Haber, R. Carminati, and S. Rotter, PNAS 111, 17765 (2014)
[2] R. Savo, R. Pierrat, U. Najar, R. Carminati, S. Rotter, and S. Gigan, Science 358, 765 (2017)
[3] M. Davy, M. Kühmayer, S. Gigan, and S. Rotter, Communications Physics 4, 85 (2021)
[4] M. Horodynski, D. Bouchet, M. Kühmayer, and S. Rotter, Phys. Rev. Lett. 127, 233201 (2021)
[5] L. M. Rachbauer, D. Bouchet, U. Leonhardt, and S. Rotter (manuscript in preparation
Non-Hermitian channels of invisibility across complex media
No full textWaves typically propagate very differently through a homogeneous medium like free space than through an inhomogeneous medium like a complex dielectric structure. It has thus been quite surprising to find that one-dimensional scattering systems can be engineered in such a way that by way of the gain and loss added to them, they become not only reflection-less, but entirely scattering-free [1,2], even for pulses propagating through them [3]. Our most recent insight is that a straightforward way to extend these non-Hermitian features to two-dimensional space is to map the wave solutions in free space to those inside a suitably designed non-Hermitian potential landscape such that both solutions share the same spatial distribution of their wave intensity [4]. This mapping turns out to be broadly applicable as a design protocol for a special class of non-Hermitian media across which specific incoming waves form scattering-free propagation channels. This protocol naturally enables the design of structures with a broadband unidirectional invisibility for which outgoing waves are indistinguishable from those of free space. We illustrate this concept through the example of a beam that maintains its Gaussian shape while passing through a randomly assembled distribution of scatterers with gain and loss.
[1] K. G. Makris, A. Brandstötter, P. Ambichl, Z. H. Musslimani, and S. Rotter, Light Sci. Appl. 6, e17035 (2017)
[2] E. Rivet, A. Brandstötter, K. G. Makris, H. Lissek, S. Rotter, and R. Fleury, Nature Physics 14, 942 (2018)
[3] A. Brandstötter, K. G. Makris, and S. Rotter, Phys. Rev. B 99, 115402 (2019)
[4] K. G. Makris, I. Kresić, A. Brandstötter, and S. Rotter, Optica 7, 619 (2020
Fisher information in scattering problems and neural networks
No full textIn my talk, I will discuss recent progress in applying the concept of Fisher information to the problem of estimating system parameters in complex scattering environments, such as inside or behind a disordered medium [1,2,3]. We have recently realised that such tools can also be successfully applied to artificial neural networks, in particular to define the performance limit of a network in extracting information from a complex system.
[1] Maximum information states for coherent scattering measurements, D. Bouchet, S. Rotter, and A. P. Mosk, Nature Physics 17, 564 (2021).
[2] Optimal control of coherent light scattering for binary decision problems, D. Bouchet, L. M. Rachbauer, S. Rotter, A. P. Mosk, and E. Bossy, Phys. Rev. Lett. 127, 253902 (2021).
[3] Invariance property of the Fisher information in scattering media, M. Horodynski, D. Bouchet, M. Kühmayer, and S. Rotter, Phys. Rev. Lett. 127, 233201 (2021)
Fisher Information in Electromagnetism
No full textIn my talk, I will discuss recent progress in applying the concept of classical and
quantum Fisher informa;on to the problem of estimating system parameters in
electromagnetic scattaering and nano-photonics. Specifically, I will demonstrate how Fisher Information can be maximised through wavefront shaping and quantum state engineering [1,2]. Quite interestingly, the density and flux of Fisher information satisfy a fundamental continuity equation – in analogy to the Poynting theorem for the density and flux of energy in a radiation field [3]. This viewpoint allows us to identify Fisher information a physical quantity that propagates through space and that can resonate, diffract, and interfere [4]. Finally, I will also say a few words about how such concepts can be generalised to the flow of Fisher Information through Artificial Neural Networks [5].
[1] Maximum information states for coherent scattaering measurements, D. Bouchet, S. Rotter, and A. P. Mosk, Nature Physics 17, 564 (2021).
[2] How to find optimal quantum states for optical micromanipulation and metrology in complex scattering problems, L. M. Rachbauer, D. Bouchet, U. Leonhardt, and S. Rotter, J. Opt. Soc. Am. B 41, 2122 (2024)
[3] Continuity equation for the flow of Fisher information in wave scattering, J. Hüpfl, F. Russo, L. M. Rachbauer, D. Bouchet, J. Lu, U. Kuhl, and S. Rotter, Nature Physics 20, 1294 (2024)
[4] Controlling the flow of information in optical metrology, M. Weimar, H. Zhou, L. Neubacher, T. A. Grant, J. Hüpfl, K. F. MacDonald, S. Rotter, and N. I. Zheludev, arXiv:2508.13640
[5] Fisher information flow in artificial neural networks, M. Weimar, L. M. Rachbauer, I.
Starshynov, D. Faccio, L. Adilova, D. Bouchet, and S. Rotter, Phys. Rev. X 15, 031072 (2025
Non-Hermitian Topology in Lasers and Anti-Lasers
No full textn my presentation, I will first speak about the topological aspects of encircling an exceptional point (EP) in a laser and the corresponding chiral state transfer [1]. Building on the insight that EPs can also be identified in the absorption spectra of anti-lasers [2], I will present experimental results on the chiral and degenerate perfect absorption at an EP [3]. Finally, I will show how not only two modes can be critically coupled, but more than a thousand – leading to a massively degenerate coherent perfect absorber for arbitrary incoming wavefronts [4].
[1] A. Schumer, Y. G. N. Liu, J. Leshin, L. Ding, Y. Alahmadi, A. U. Hassan, H. Nasari, S. Rotter, D. N. Christodoulides, P. LiKamWa, and M. Khajavikhan, Science 375, 884 (2022)
[2] W. R. Sweeney, C. W. Hsu, S. Rotter, and A. D. Stone, Phys. Rev. Lett. 122, 093901 (2019)
[3] S. Soleymani, Q. Zhong, M. Mokim, S. Rotter, R. El-Ganainy, and S. K. Özdemir, Nature Commun. 13, 599 (2022)
[4] Y. Slobodkin, G. Weinberg, H. Hörner, K. Pichler, S. Rotter, and O. Katz, Science 377, 995 (2022
Coherent perfect absorption and emisson of light in non-Hermitian and time-varying media
No full textIn this talk, I will speak about our recent work on coherent perfect absorption (CPA) [1,2] and emission [3] of light in tailor-made resonators. I will highlight, in particular, the possibility to engineer spatial and spectral degeneracies for broadband absorption of arbitrary wavefrontsat an exceptional point as well as the topological aspects associated with perfect emission of thermal radiation. In the second part of my presentation, I will present new insights on the CPA effect in time-varying media, which can be well described by a pseudo-unitary Floquet scattering matrix [4].
[1] Y. Slobodkin, G. Weinberg, H. Hörner, K. Pichler, S. Rotter, and O. Katz, Science 377, 995 (2022)
[2] H. Hörner, L. Wild, Y. Slobodkin, G. Weinberg, O. Katz, and S. Rotter, Phys. Rev. Lett. 133, 173801 (2024).
[3] M. S. Ergoktas, A. Keçeba¸s, K. Despotelis, S. Soleymani, G. Bakan, A. Kocaba¸s, A. Principi, S. Rotter, ¸S. K. Özdemir, and C. Kocaba¸s, Science 384, 1122 (2024).
[4] D. Globosits, J. Hüpfl, and S. Rotter, Phys. Rev. A 110, 053515 (2024)
Multiple Light Fields at Critical Coupling
No full textI will speak about light fields at the condition of critical coupling, with an emphasis on the design of optical systems, where multiple modes satisfy this condition in parallel. As we have shown in recent collaborations with experimental teams, such systems show unique behaviour, such as degenerate perfect absorption [1], as well as perfect transmission of arbitrary coherent wavefronts even across disordered media [2].
References:
1. Y. Slobodkin, G. Weinberg, H. H ̈orner, K. Pichler, S. Rotter, and O. Katz, Science 377, 995 (2022).
2. M. Horodynski, M. Ku ̈hmayer, C. Ferise, S. Rotter, and M. Davy, Nature 607, 281 (2022)
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