April 2016 Heilborn Lecture


Prof. David Wineland


Recipient of the 2012 Nobel Prize

National Institute of Standards & Technology


April 18-22


David Wineland recieved the 2012 Nobel Prize in Physics along with Serge Haroche "for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems."  Professor Wineland received his doctroal training under Norman F. Ramsey, the Nobel Laureate whose work led to the atomic clock.  After his postdoctoral work at the University of Washington he joined the National Bureau of Standards (now NIST).  He pioneered the technology to laser cool ions, and his group now conducts experiments on atomic ions that are confined in electromagnetic traps and laser-cooled.  Prof. Wineland is the recipient of the Benjamin Franklin Medal, Frederic Ives Medal, and the National Medal of Science for Engineering. 













May 13

Twist-controlled electronic properties of van der Waals Heterostructures.


Recent developments in the technology of van der Waals heterostructures made from two-dimensional atomic crystals have already led to the observation of new physical phenomena, such as the metal-insulator transition and Coulomb drag, and to the realisation of functional devices, such as tunnel diodes, tunnel transistors and photovoltaic sensors. An unprecedented degree of control of the electronic properties is available not only by means of the selection of materials in the stack but also through the additional fine-tuning achievable by adjusting the built-in strain and relative orientation of the component layers. I will discuss several physical phenomena which are a direct result of the crystallographic alignment of the 2D crystals in such stacks.




May 15

Materials in the Flatland


When one writes by a pencil, thin flakes of graphite are left on a surface. Some of them are only one atom thick and can be viewed as individual atomic planes cleaved away from the bulk. Such one atom thick crystals of graphite (dubbed graphene) turned out to be the strongest crystals available to us, the most conductive, most thermally conductive, most elastic, flexible, transparent material, etc, etc, etc. Its electronic properties are particularly exciting: its quasiparticles are governed by the Dirac equation so that charge carriers in graphene mimic relativistic particles with zero rest mass.


Still, probably the most important “property” of graphene is that it has opened a floodgate of experiments on many other 2D atomic crystals: BN, NbSe2, TaS2, MoS2, etc. The resulting pool of 2D crystals is huge, and they cover a massive range of properties: from the most insulating to the most conductive, from the strongest to the softest.

If 2D materials provide a large range of different properties, sandwich structures made up of 2, 3, 4 … different layers of such materials can offer even greater scope. Since these 2D-based heterostructures can be tailored with atomic precision and individual layers of very different character can be combined together, - the properties of these structures can be tuned to study novel physical phenomena or to fit an enormous range of possible applications, with the functionality of heterostructure stacks is “embedded” in their design.