About

Physics explores the natural world. Advances in physics lead to new technologies. Students in physics acquire mathematical skills and ways of thinking that support success in many careers. Many of our physics graduates have gone on to earn graduate degrees in physics. Many others have succeeded in law, medicine, engineering, business and finance.

The Department of Physics has state-of-the-art laboratory equipment for introductory, intermediate and advanced experiments in mechanics, electromagnetism, optics, lasers, electronics, quantum and nuclear physics. A weekly colloquium brings physicists from all over the world to present and discuss their research.

Recent Colloquia: Spring 2013

April 9
Paul Brumer, Department of Chemistry, University of Toronto
Coherence, Decoherence, and Incoherence in Natural Light Harvesting Systems

Abstract:
A number of 2D Photon Echo experiments have shown the presence of long-lived coherences in light harvesting systems, such as FMO and PC645. Such studies have led to conjectures about the role of quantum coherences in biology, leading to arguments in favor of "quantum biology." However, experiments of this kind involve excitation with coherent laser sources, whereas nature irradiates with essentially incoherent sunlight/moonlight. We discuss the differing responses of molecular systems to coherent vs. incoherent excitation in both open and closed quantum systems, demonstrating that the experimentally observed coherences, although revealing features of the system Hamiltonian and of the system-bath interactions, do not argue for quantum coherent evolution in nature.

April 23
Luat Vuong
Queens College, CUNY
Demonstrations of Photo-induced Magnetism in Metallic Nanocolloids Uusing Sunlight and Fridge Magnets

Abstract:
The focus of this talk is on nonlinear plasmonic vortex dynamics, which are far from understood and lead to appreciable photo-induced magnetic fields in metallic nanostructures.

We have recently experimentally, analytically and numerically demonstrated the nonlinear photo-induced plasmon-assisted magnetic response that occurs with 80-nm gold particles in aqueous solution. The anomalously large magnetic response-theoretically considered too small to observe at room temperature- was observed using light from a solar simulator and small (micro-to-milli-Tesla) magnetic fields. I will explain why the effect is observable using disperse nanocolloidal liquids and present our theoretical model of an increased and anisotropic electrical conductivity, which yields modified absorption spectra in agreement with our experimental results.

This work, which is the first nano-demonstration of old physics, improves our fundamental understanding of surface charges in nanostructures and aids the development of broad-band photonics metamaterials, new polarization-encoded imaging methods, photocatalytic materials, photovoltaic devices, and sensors.

April 30
Bala Sundaram
University of Massachusetts, Boston
Structural and Dynamical Aspects of Networks: Some New Results

Abstract:
The talk addresses two aspects of our work where I will first discuss a new mechanism for generating networks with a wide variety of degree distributions. The idea is variation of the well-studied preferential attachment scheme in which the degree of each node is used to determine its evolving connectivity. Though modifications to this base protocol, involving features other than connectivity have been considered, schemes based on preferential attachment in any form require substantial information about the network. We propose instead a parsimonious protocol based only on a single statistical feature which results from the reasonable assumption that the effect of various attributes, which determine the affinity of each node to other nodes, is multiplicative. This composite attribute or fitness is then used in forming the complex network. It is shown that, by varying a single statistical parameter, we can recover all known degree distributions. In the case of power-law networks, the exponents exhibit a range consistent with that seen in real-world networks and the network exhibits other attributes seen in data. In the last part of the talk, a variety of applications will be discussed including the issue of robustness and centrality, as well as pattern formation and dynamics on complex networks.

Past Colloquia

Read about our past colloquia (PDF).

If you have any questions about physics at Yeshiva College, please contact Professor Zypman at zypman@yu.edu or 212.960.5400, ext.104.