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ICFO > Event > Ewold Verhagen (AMOLF)
Schools
From July 1, 2024 to July 3, 2024
Ewold Verhagen (AMOLF)

All day

Place: ICFO Auditorium

Ewold Verhagen (AMOLF)

BIO:

Ewold Verhagen leads the Photonic Forces group in the Center for Nanophotonics at AMOLF, and is part-time professor of Applied Physics at Eindhoven University of Technology. His group studies light-matter interactions at the nanoscale, in particular the coupling between photons and phonons in nano-optomechanical systems. Verhagen seeks to understand how the behavior of light and sound in nanoscale devices is governed by fundamental principles such as spatiotemporal symmetries and quantum mechanics. With his group, he explores how suitable system design and control over light-matter interactions can engage the conventional limits to nanophotonic and nanomechanical functionality, in application domains from sensing and metrology to communication.

TALK: "Nonreciprocity and topology in optomechanical meta-matter"

We explore the unusual states of mechanical motion that emerge in resonator networks that are fully induced and controlled through radiation pressure drives. Temporal modulation of the interactions between photons and phonons in on-chip silicon nano-optomechanical systems allow creating arbitrary quadratic bosonic Hamiltonians for small collections of mechanical resonators. Judicious breaking of time-reversal symmetry and Hermiticity then induces collective mechanical ‘metamaterial’ responses that are unlike those of regular, passive materials. These include unidirectional flow of sound, as well as topological phononic states such as the quantum Hall effect and a bosonic version of the Kitaev chain. I will discuss the implications of the observed phenomena for directional amplification and sensing enhancement

TUTORIAL "Quantum geometry of 2D materials: from anomalous photoresponse to bulk photovoltaics"

With Frank Koppens (ICFO)

Quantum geometry of two-dimensional (2D) materials has emerged as a pivotal area in solid-state physics, influencing a wide range of phenomena from anomalous photoresponses to bulk photovoltaic effects. This tutorial addresses the intricate interplay between quantum geometry and the electronic properties of 2D materials, with a focus on the manifestation of these effects in practical applications. A tangible example is the bulk photovoltaic effect (BPVE), a process where a material generates a direct current under uniform illumination without the need for a p-n junction, as seen in traditional photovoltaic devices.
A special emphasis is placed on twisted bilayer graphene (TBG), a material that has garnered significant attention due to its highly tunable electronic structure and the emergence of flat bands at specific twist angles. In TBG, the interplay between moiré superlattice potentials and quantum geometric properties enhances the BPVE, making it a promising candidate for novel photovoltaic applications. We provide a comprehensive overview of how quantum geometry governs the optoelectronic responses in 2D materials, paving the way for innovative technological advancements in the field of photovoltaics.
 
Schools
From July 1, 2024 to July 3, 2024
Ewold Verhagen (AMOLF)

All day

Place: ICFO Auditorium

Ewold Verhagen (AMOLF)

BIO:

Ewold Verhagen leads the Photonic Forces group in the Center for Nanophotonics at AMOLF, and is part-time professor of Applied Physics at Eindhoven University of Technology. His group studies light-matter interactions at the nanoscale, in particular the coupling between photons and phonons in nano-optomechanical systems. Verhagen seeks to understand how the behavior of light and sound in nanoscale devices is governed by fundamental principles such as spatiotemporal symmetries and quantum mechanics. With his group, he explores how suitable system design and control over light-matter interactions can engage the conventional limits to nanophotonic and nanomechanical functionality, in application domains from sensing and metrology to communication.

TALK: "Nonreciprocity and topology in optomechanical meta-matter"

We explore the unusual states of mechanical motion that emerge in resonator networks that are fully induced and controlled through radiation pressure drives. Temporal modulation of the interactions between photons and phonons in on-chip silicon nano-optomechanical systems allow creating arbitrary quadratic bosonic Hamiltonians for small collections of mechanical resonators. Judicious breaking of time-reversal symmetry and Hermiticity then induces collective mechanical ‘metamaterial’ responses that are unlike those of regular, passive materials. These include unidirectional flow of sound, as well as topological phononic states such as the quantum Hall effect and a bosonic version of the Kitaev chain. I will discuss the implications of the observed phenomena for directional amplification and sensing enhancement

TUTORIAL "Quantum geometry of 2D materials: from anomalous photoresponse to bulk photovoltaics"

With Frank Koppens (ICFO)

Quantum geometry of two-dimensional (2D) materials has emerged as a pivotal area in solid-state physics, influencing a wide range of phenomena from anomalous photoresponses to bulk photovoltaic effects. This tutorial addresses the intricate interplay between quantum geometry and the electronic properties of 2D materials, with a focus on the manifestation of these effects in practical applications. A tangible example is the bulk photovoltaic effect (BPVE), a process where a material generates a direct current under uniform illumination without the need for a p-n junction, as seen in traditional photovoltaic devices.
A special emphasis is placed on twisted bilayer graphene (TBG), a material that has garnered significant attention due to its highly tunable electronic structure and the emergence of flat bands at specific twist angles. In TBG, the interplay between moiré superlattice potentials and quantum geometric properties enhances the BPVE, making it a promising candidate for novel photovoltaic applications. We provide a comprehensive overview of how quantum geometry governs the optoelectronic responses in 2D materials, paving the way for innovative technological advancements in the field of photovoltaics.