Archiv 2020

Local magnetic measurements of quantum materials

Max Planck Quantum Matter Seminar

Communication and Conflict Management (IMPRS UFAST skills course)

IMPRS UFAST skills course

To thermalize or not to thermalize?

Max Planck Lecture on Non-Equilibrium Quantum Phenomena

Pairing electrons via photons and vice versa

Max Planck Quantum Matter Seminar

Source Technology (IMPRS UFAST core course)

IMPRS UFAST core course

Extreme Photonics with Nanogap Cavities

Max Planck Lecture on Non-Equilibrium Quantum Phenomena

Ultrafast enhancement of exchange interaction and short range spin correlations probed bymagnetoelastic coupling in CrSiTe3

Max Planck Quantum Matter Seminar

Polaritons and ultrasmall cavities in twisted 2D material heterostructures

Max Planck Lecture on Non-Equilibrium Quantum Phenomena

Project and Time Management (IMPRS UFAST skills course)

IMPRS UFAST core course

Introduction to LabVIEW for PhD students (IMPRS UFAST skills course)

IMPRS UFAST skills course

Introduction to Machine Learning with Python (IMPRS UFAST skills course)

IMPRS UFAST skills course

Coupling free-electrons and whispering gallery modes

Free-electron beams in dedicated electron microscopes are an extremely functional probe for microstructure and composition [1]. Technological improvements in electron-beams control have repeatedly revolutionized the scientific reach of nanoscopic phenomena, with examples as aberration correctors [2] and the Nobel-winning cryo-electron-microscopy [3]. Light – the newest insertion into electron microscopes – creates novel ultrafast imaging modalities, facilitating direct observations of dynamics in phase transitions [4], phonons [5,6], and more. However, the weak coupling of electrons with photons is a limiting factor for emerging applications [7,8] of light-based electron control.This talk presents a roadmap towards a strong coupling of electrons and light, using whispering gallery mode (WGM) microresonators [9,10]. I will start by discussing the important properties of these rotating modes for electron-light coupling. I describe the expected entanglement of electrons and photons, the statistical properties of the electron-photon states, and show that in the weak coupling regime they disentangle and reproduce known phenomena. Experimentally, I show how basic features of WGMs, such as light storage, modal population, and light coupling are expressed in the interaction with electrons. Importantly, an optimized arrangement of microresonators drives a dramatic modulation of the electron beam, expressed as a broad and coherent electron-energy spectrum. In the future, the strong-coupling of electrons to resonant optical modes can be used for fundamental electron-photon research, such as entangled electron-photon pairs, optical electron-phase manipulation, and generally, the merging of electrons into the realm of quantum optics. Furthermore, the combination of resonators with electron microscopy allows for dynamical imaging and spectroscopy with nanometer resolution and a temporal resolution down to the attosecond-scale. [mehr]
Dear female PhD students and postdocs, the registration site for this year’s Women’s Career Day is open now. In two tailor-made workshops you are invited to strengthen key skills that are useful for your present and future professional career, be that within academia or in business and industry. [mehr]
CANCELLATION - Please note that due to the spread of the coronavirus disease (COVID-19) this workshop has been cancelled. [mehr]
CANCELLATION - Please note that due to the spread of the coronavirus disease (COVID-19) this seminar has been cancelled. [mehr]

Light-field-driven currents in graphene

Dirac fermions and flat bands in the ideal kagome metal FeSn

Signatures of the quantum vacuum

MPSD Seminar
The quantum vacuum is one of the most counter-intuitive concepts of quantum electrodynamics. Whereas the classical vacuum refers to a region of space that is devoid of any particles or fields, its quantum counterpart contains fluctuating electromagnetic fields even in the most idealised case. As predicted by macroscopic quantum electrodynamics, the structure of these virtual photons can be significantly altered by the presence of magnetodielectric bodies or media. The signature of the quantum vacuum is manifest in the interaction of virtual photons with charged matter. [mehr]

Symmetries in high harmonic generation and their application to novel ultrafast spectroscopies

MPSD Seminar
The analysis of symmetries and their associated selection rules is extremely useful in many fields of science. The field of nonlinear optics is no exception. In the early days of nonlinear optics, symmetries were used to derive whether particular nonlinear optical processes are allowed/forbidden according to the medium’s point-group. This approach is believed to be complete, and is regularly taught in graduate classes. [mehr]

Near-Field Physics and Chemistry in Plasmonic STM junctions

MPSD Seminar
Plasmonic cavities exhibit many intriguing properties and phenomena resulting from strong field enhancement and confinement. Recently, both experimental and theoretical studies have revealed crucial roles of atomistic structures and quantum mechanical effects in plasmonic nanostructures [1-3]. [mehr]

Presentation Skills (IMPRS-UFAST Skills Course)

IMPRS-UFAST skills course
“Poets are born – speakers are made” Public speaking is a necessity in scientific life. Take part in this two-days course, find out what your strengths are and develop your individual presentation profile. Take steps to learn how to lead the audience from your first appearance on stage until the last question in the discussion. Be authentic, enthusiastic and convincing! [mehr]

Cavity Optomagnonics

MPSD Seminar
Optomagnonics studies the quantum-coherent coupling of light to collective magnetic excitations in solid state systems. The magnetic material hosting the magnetic excitations can be also used as an optical cavity if patterned appropriately. This not only enhances the magnon-photon coupling (making these systems promising for applications in quantum technologies) but also allows studying cavity-modified light-matter interaction in a novel platform. In my talk I will go over the basics of cavity optomagnonics and present results on recent theory developments in my group, including optomagnonics with magnetic textures, optical heralding of magnon Fock states, and antiferromagnetic cavity optomagnonics.

Controlling superconductivity with the electromagnetic vacuum

MPSD Seminar
Exploiting light-matter interactions to control collective quantum phenomena in solids is an ongoing broad research effort. In particular, it is known that superconductivity can be strongly modified using an external radiation [1-3]. In the absence of the latter, it is an interesting question whether superconductivity induced by conventional Cooper pairing may be also affected by coupling phonons to the electromagnetic field confined in a cavity with enhanced vacuum fluctuations [4,5]. [mehr]
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