2022

Branching High-Order Exceptional Points in Non-Hermitian Optical Systems
K. Tschernig, K. Busch, D.N. Christodoulides, and A. Perez-Leija (2022)
Laser & Photonics Reviews
Exceptional points are complex-valued spectral singularities that lead to a host of intriguing features such as loss-induced transparency—a counterintuitive process in which an increase in the...
Linear response theory of open systems with exceptional points
S. Hashemi, K. Busch, D.N. Christodoulides, S.K. Ozdemir, and R. El-Ganainy (2022)
Nature Communications 13:3281

Understanding the linear response of any system is the first step towards analyzing its linear and nonlinear dynamics, stability properties, as well as its behavior in the presence of noise. In...

Quantum-inspired multicore optical fiber
A. Kalita, Q. Zhong, K. Busch, and R. El-Ganainy (2022)
Optics Letters 47:2526

We introduce a new, to the best of our knowledge, type of multicore optical fiber having a quantum-inspired network topology and unique spectral features. Particularly, the connectivity between...

In der Unruhe liegt die Kraft
F. Intravaia, D. Reiche, und K. Busch (2022)
Physik Journal 21:35

Fluktuationen sind allgegenwärtig. Sie bilden einen fundamentalen Baustein der Quantenmechanik und sind verantwortlich für die unterschiedlichsten Phänomene von der Biologie bis zur Kosmologie....

Nanostructured In3SbTe2 antennas enable switching from sharp dielectric to broad plasmonic resonances
A. Heßler, S. Wahl, P.T. Kristensen, M. Wuttig, K. Busch und T. Taubner (2022)
Nanophotonics

Phase-change materials (PCMs) allow for non-volatile resonance tuning of nanophotonic components. Upon switching, they offer a large dielectric contrast between their amorphous and crystalline...

Topological protection of partially coherent light
K. Tschernig, G. Martinez-Niconoff, K. Busch, M.A. Bandres, and A. Perez-Leija (2022)
Photonics Research 10:1223

Topological physics exploits concepts from geometry and topology to implement systems capable of guiding waves in an unprecedented fashion. These ideas have led to the development of photonic...

Modulated light potentials for state manipulation of quasiparticles in ultra-cold Bose gases
B. Maaß, D. Hartley, K. Busch, and D. Rätzel (2022)
New Journal of Physics 24:043014

Ensembles of ultra-cold atoms have been proven to be versatile tools for high precision sensing applications. Here, we present a method for the manipulation of the state of trapped clouds of...

Wading through the void: Exploring quantum friction and nonequilibrium fluctuations
D. Reiche, F. Intravaia, and K. Busch (2022)
APL Photonics 7:030902

When two or more objects move relative to one another in vacuum, they experience a drag force, which, at zero temperature, usually goes under the name of quantum friction. This contactless non-...

2021

Tailored Disorder in Photonics: Learning from Nature
M. Rothammer, C. Zollfrank, K. Busch, and G. von Freymann (2021)
Advanced Optical Materials 9:2100787

Disorder and photonics have long been seen as natural adversaries and designers of optical systems have often driven systems to perfection by minimizing deviations from the ideal design....

Direct observation of the particle exchange phase of photons
K. Tschernig, C. Müller, M. Smoor, T. Kroh, J. Wolters, O. Benson, K. Busch, and A. Perez-Leija (2021)
Nature Photonics 15:671

Quantum theory stipulates that if two particles are identical in all physical aspects, the allowed states describing the system are either symmetric or antisymmetric with respect to permutations...

Topological protection of highly entangled non-Gaussian two-photon states
K. Tschernig, R. Lo Franco, M. Ivanov, M.A. Bandres, K. Busch, and A. Perez-Leija (2021)
Materials for Quantum Technology 1:035001

We study theoretically the evolution of entangled non-Gaussian two-photon states in disordered topological lattices. Specifically, we consider spatially entangled two-photon states, modulated by...

Entangled two-photon absorption spectroscopy with varying pump wavelengths
L. Mertenskötter, K. Busch, and R. de de J. León-Montiel (2021)
Journal of the Optical Society of America B 38:C63

In entangled two-photon absorption (eTPA) spectroscopy, information about the energy-level structure of an arbitrary sample is retrieved by Fourier transforming sets of measured two-photon...

Topological protection versus degree of entanglement of two-photon light in photonic topological insulators
K. Tschernig, A, Jimenez-Galan, D.N. Christodoulides, M. Ivanov, K. Busch, M.A. Bandres, and A. Perez-Leija (2021)
Nature Communications 12:1974

Topological insulators combine insulating properties in the bulk with scattering-free transport along edges, supporting dissipationless unidirectional energy and information flow even in the...

Additive splitting methods for parallel solutions of evolution problems
S. Amiranashvili, M. Radziunas, U. Bandelow, K. Busch, and R. Ciegis (2021)
Journal of Computational Physics 436:110320

We demonstrate how a multiplicative splitting method of order P can be utilized to construct an additive splitting method of order P+3. The weight coefficients of the additive...

Enhanced Faraday rotation by dielectric metasurfaces with Bayesian shape-optimized scatterers
T: Kiel, P. Varytis, B. Beverungen, P.T. Kristensen, and K. Busch (2021)
Optics Letters 46:1720

In this Letter,we demonstrate howto optimize the magneto–optic response of a Huygens metasurface composed of square arrays of all-dielectric nano-disk scatterers.We compare cylindrical and shape...

Electron energy loss spectroscopy on freestanding perforated gold films
M. Prämassing, T. Kiel, S. Irsen, K. Busch, and S. Linden (2021)
Physical Review B 103:115403

We report on a combined far- and near-field study of surface plasmon polaritons on freestanding perforated gold films. The samples were fabricated by focused ion beam milling of a periodic hole...

Defect-State Lasing in Photonic Lattices of Metal–Organic Microcavities
M. Kliem, T. Kiel, M. Kück, S. Meister, A. Mischok, H. Fröb, K. Busch, and K. Leo (2021)
Advanced Photonics Research 2:2000116

Photonic band structure engineering has developed into an important technique for controlling the emission and interaction of photons and polaritons in microcavities (MCs). Herein, lasing from...

2020

Nonequilibrium thermodynamics of quantum friction
D. Reiche, F. Intravaia, J.-T. Hsiang, K. Busch, and B.L. Hu (2020)
Physical Review A (rapid) 102:050203

Thermodynamic principles are often deceptively simple and yet surprisingly powerful.We show how a simple rule, such as the net flow of energy in and out of a moving atom under a nonequilibrium...

Modeling electromagnetic resonators using quasinormal modes
P.T. Kristensen, K. Herrmann, F. Intravaia, and K. Busch (2020)
Advances in Opics and Photonics 12:612

We present a biorthogonal approach for modeling the response of localized electromagnetic resonators using quasinormal modes, which represent the natural, dissipative eigenmodes of the system...

On the applicability of quantum-optical concepts in strong-coupling nanophotonics
C. Tserkezis, A. I. Fernandez-Dominguez, P. A. D. Goncalves, F. Todisco, J. D. Cox, K. Busch, N. Stenger, S. I. Bozhevolnyi, N. A. Mortensen, and C. Wolff (2020)
Reports on Progress in Physics 83:82401

Rooted in quantum optics and benefiting from its well-established foundations, strong coupling in nanophotonics has experienced increasing popularity in recent years. With nanophotonics being an...

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