Groups | Seminars || Courses | Outreach


Seminars will be held in room S-141 in the Physics and Astronomy Department building on Mondays at 4:00 PM, unless noted otherwise. When necessary, virtual seminar Zoom login instructions will be sent out via email. 


Spring/Summer 2024

March 18, 2024

Dr. Thomas Pattard
Editor, Physical Review A

How (not) to get your paper published in a physics journal

(Host: Jesús Pérez Ríos)

Have you done some amazing research, but are unsure how to communicate the results? Have you ever wondered how the process of scientific publishing and peer review works, and what goes on in the mind of an editor (or if they even have one)? In this talk, I will try to give some insight into the process of publishing in a scientific journal from the perspective of an editor. After a very brief introduction to the world of physics publishing, I will discuss how to write a scientific paper, and what to keep in mind while doing so. In the last part of the talk, I will give a short overview of the peer review process and the workflow associated with the consideration of a typical manuscript, and give some pointers on how to successfully navigate the process as an author.

April 5, 2024, 12:00 PM

Prof. Alexander Lvovsky
Department of Physics, Oxford University
Optical neural networks for faster AI and superresolution imaging

(Host: Eden Figueroa)

Although machine intelligence is taking over the world, its current digital electronic platform is very inefficient in terms of energy consumption. Switching to analogue computation, which function more like human brains than digital computers, will allow enhancing the energy efficiency by several orders of magnitude. Optics presents a particularly promising platform for analogue AI; however, significant challenges – particularly in the domain of neural network training – must be overcome before it can compete with its digital counterpart. A likely upcoming range of applications of optical neuron networks is in computer vision, as they will allow eliminating the bottleneck associated with back-and-forth conversion of data between optical and electronic formats. A further benefit of optical processing is enhancing the quality of imaging. For example, it allows reaching the quantum frontier of imaging resolution beyond Rayleigh’s diffractive limit which applies to most of the modern classical imaging technology.

April 8, 2024

Dr. Angela Pizzuto
Raytheon Technologies
Linear and Nonlinear Terahertz Near-Field Microscopy for Characterizing Electronic Systems

(Host: Harold Metcalf)

Terahertz scattering scanning near field optical microscopy (THz s-SNOM) has become an active research topic for its effectiveness in characterizing electronic behavior in many materials with nanoscale resolution. Motivated by a desire to understand the current techniques more deeply and to expand upon them, here we present novel methods for characterizing metals and semiconductors with THz s-SNOM.

First, we demonstrate the first “nonlocal” near-field optical pump-terahertz probe experiments, in which we photoexcite bulk undoped GaAs and use a THz probe pulse to observe the change in reflection at an area laterally displaced from our pump. We demonstrate that this technique can be used to reveal anisotropy in a sample by highlighting directions of preferred carrier motion. Next, we expand this technique to nonlocal laser terahertz emission nanoscopy (LTEN), in which we detect THz emission from bulk InAs at a location displaced from our pump area. We determine that both techniques can reveal properties related to carrier motion, but the latter can also illustrate mechanisms of THz generation which are poorly understood in certain materials.

Finally, we demonstrate the first instance of blue light LTEN. We show that inducing THz emission in semiconductors via high-energy pumping can reveal properties of charge carriers in higher bands not observable with conventional near-infrared pumping. We create the first near-field THz emission image of bulk Si and provide a novel framework for correlating the emission strength to the Si doping profile.

April 15, 2024

Prof. David J. Wineland
Nobel Laureate, Physics (2012)
University of Oregon
Atomic Clocks

(Host: Harold Metcalf)

[not available]

April 22, 2024

Debadarshini Mishra
UConn, Berrah Lab
Imaging time-resolved dynamics in molecular systems

(Host: Tom Weinacht)

Imaging electronic and molecular dynamics at the attosecond and femtosecond timescales is crucial for understanding the mechanisms of chemical reactions, a fundamental aspect in fields ranging from materials science to biochemistry. This in-depth understanding of chemical processes may allow for precise control over reaction dynamics, thereby paving the way for advancements in technology and medicine, for example, by guiding the development of efficient catalysis, innovative materials, and targeted drugs. In this talk, I will describe our work on imaging time-resolved molecular dynamics using two distinct and complementary techniques.

In the first part of my talk, I will discuss the use of coincident Coulomb explosion imaging for the direct visualization of roaming reactions. These reactions represent unconventional pathways that allow fragments to remain weakly bonded, leading to the formation of unexpected final products. Typically, the neutral character of the roaming fragment and its indeterminate trajectory make direct experimental identification challenging. However, I will demonstrate that by leveraging the power of coincidence imaging, we can reconstruct the momentum vector of the neutral roamer and thus identify an unambiguous signature for roaming.

In the second part of my talk, I will discuss the imaging of UV-induced ring-opening and dissociation dynamics using ultrafast electron diffraction. I will demonstrate that by harnessing the superior temporal and structural resolution of this technique, we can explore the competition among different molecular pathways as well as their wavelength-dependent behavior.

June 17, 2024

Dr. Federico Roccati
Columbia University
Quantum optics in (non-)Hermitian topological photonic reservoirs

(Host: Dominik Schneble)

Topology and quantum optics are two fields whose interplay can give rise to new physics [1]. By properly designing a photonic lattice (i.e., the structured reservoir), it is possible to engineer photon-mediated spin Hamiltonians between quantum emitters coupled to it. In particular, it is possible to endow photonic structures with Hermitian or non-Hermitian topological properties, the latter being typical of dissipative lattices [2]. In my talk, I will cover the recent advancements in the field, the current experimental implementations of such setups, and our recent results. Specifically, I will describe how, engineering dissipation (i.e., non-Hermiticity) in a photonic lattice, exotic interactions can be mediated between quantum emitters, unachievable in the Hermitian case [3]. Finally, I will illustrate the topological correspondence that exists between the topology of a photonic lattice and the topology of the photon-mediated interactions [4].

[1] M. Bello, G. Platero, J. I. Cirac, A. González-Tudela. Sci. Adv. 5, eaaw0297 (2019).
[2] T. Ozawa et al. Rev. Mod. Phys. 91, 015006 (2019).
[3] F. Roccati, S. Lorenzo, G. Calajò, G. M. Palma, A. Carollo, F. Ciccarello. Optica 9, 565-571 (2022).
[4] F. Roccati, M. Bello, Z. Gong, M. Ueda, F. Ciccarello, A. Chenu, A. Carollo. Nat Commun 15, 2400 (2024)