Spring 2017

Electromechanics: A New Quantum Technology

Speaker(s): 
Konrad Lehnert
Dates: 
Monday, March 27, 2017 - 4:30pm to 5:30pm

Devices that combined electricity with moving parts were crucial to the very earliest electronic communications. Today, electromechanical structures are ubiquitous yet under-appreciated signal processing elements. These devices exploit the relative slowness of sound compared to light to create compact filter and clock elements. Moreover they convert force and acceleration signals into more easily processed electrical signals. Can these humble, apparently classical, objects exhibit genuinely quantum behavior? Indeed, by strongly coupling the vibrations of a...

Applying Ideas of Visual Cognition to Problem Solving in Physics

Speaker(s): 
Sanjay Rebello
Dates: 
Monday, March 13, 2017 - 4:30pm to 5:30pm

Problem solving is a major emphasis area of physics education that has been studied extensively over the past several decades. Frequently, physics problems – and their solutions – have strong visuospatial components. However, most research on physics problem solving has not drawn from research in visual cognition. Over the past four years a collaboration of physics education researchers and visual cognitive psychologists has been exploring and exploiting the link between cognition and eye movements manipulated by cueing and feedback to facilitate physics...

From Conjectures to Paradigms: the Evolving Influence of Field Theory and Topology in Condensed Matter

Speaker(s): 
Rajiv Singh
Dates: 
Monday, February 27, 2017 - 4:30pm to 5:30pm

The 2016 Nobel Prize in Physics to Kosterlitz, Thouless and Haldane honors a new set of ideas and theoretical formalism that has gradually become the mainstay of modern condensed matter thinking. Quantum Field Theory, Topology and the Renormalization Group, lie at the heart of present day theory of condensed matter. The Kosterlitz-Thouless theory of phase transitions and Haldane's conjecture on the spin dependence of spectrum of spin-chains were two of the most influential works in bringing these ideas together. These along with the Thouless-Kohmoto-Nightingale-Den Nijs-(TKNN) work on...

New Topological Phases and Effects in Solids

Speaker(s): 
Joel Moore
Dates: 
Monday, January 30, 2017 - 4:30pm to 5:30pm

Much of condensed matter physics is concerned with understanding how different kinds of order emerge from interactions between a large number of simple constituents. In ordered phases such as crystals, magnets, and superfluids, the order is understood through "symmetry breaking": in a crystal, for example, the continuous symmetries of space under rotations and translations are not reflected in the ground state. A major discovery of the 1980s was that electrons confined to two dimensions and in a strong magnetic field exhibit a completely different, topological type of...

Whispering Galleries and Berry Phase Switches in Circular Graphene Resonators

Speaker(s): 
Joseph Stroscio
Dates: 
Tuesday, January 12, 2016 - 4:00pm to 5:00pm

Ballistic propagation and the light-like dispersion of graphene charge carriers make graphene an attractive platform for optics-inspired graphene electronics where gate tunable potentials can control electron refraction and transmission. In analogy to optical wave propagation in lenses, mirrors and metamaterials, gate potentials can be used to create Fabry-Pérot interferometers and a negative index of refraction for Veselago lensing. In circular geometries, gate potentials caninduce whispering gallery modes (WGM), similar to optical and acoustic whispering...

Physics Enabled by the Discovery of Spin-Transfer Torques

Speaker(s): 
Andy Kent
Dates: 
Monday, February 20, 2017 - 4:30pm to 6:00pm

The magnetization of a magnetic material can be reversed by using electric currents that transport spin angular momentum. This was predicted in magnetic tunnel junctions—two thin metallic ferromagnetic layers separated by a thin insulating barrier—in 1989 and in magnetic multilayers by Luc Berger and John Slonczewski in 1996 and demonstrated experimentally several years later. This discovery has had an enormous impact on magnetism research and technology, as prior to this the primary means to reorient the magnetization of a magnet was by applying magnetic fields (dating...

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