Fall 2018

Orbital selective pairing in Fe-based superconductors

Dr. Peter Hirschfeld
Thursday, October 18, 2018 - 4:00pm

Iron-based superconductors are unconventional superconductors with relatively high Tc that derive from metallic parent compounds with several Fe d-states dominant at the Fermi level. This gives rise to a number of novel effects based on differentiated degree of correlation of the different orbital states. I discuss the influence on spin-fluctuation pairing theory of orbital selective strong correlation effects in Fe-based superconductors, particularly Fe chalcogenide systems. This paradigm yields remarkably good agreement with the experimentally observed anisotropic gap structures in both...

Variations on a theme of Aharonov and Bohm

Sir Michael Victor Berry
Tuesday, September 25, 2018 - 4:30pm to 5:30pm

The Aharonov-Bohm effect (AB) concerns the role in quantum physics of the vector potential of an impenetrable line of magnetic flux. Its partial anticipation by Ehrenberg and Siday, in terms of interference, was an approximation whose wavefunction was not singlevalued, and whose connection with the singlevalued AB wave involves topology: waves winding round the flux (‘many-whirls representation’). AB is a fine illustration of idealization in physics. There are four AB effects, depending on whether the waves and the flux are classical or quantum. In the classical-classical case, many...

2018 Conference on Materials for Quantum Computing

Multiple Speakers
Tuesday, October 30, 2018 - 8:00am to Friday, November 2, 2018 - 5:00pm

Scope: Materials science and device physics in semiconductor-superconductor heterostructures, van der Waals materials, superconducting and topological qubits.

Invited Speakers:

Philip Kim (Harvard)
Barbara Jones (IBM)
Will Oliver (MIT)
Xavier Waintal (CEA Grenoble)
Roman Lutchyn (Microsoft)
Javad Shabani (NYU)
Manuel Houzet (CEA Grenoble)
Jay Sau (Maryland)
Sebastien Plissard (Toulouse)
Andrea Young (UCSB)
Christopher Palmstrom (UCSB)
Peter Krogstrup (...

Optica fantastica: images to illuminate the physics of light

Sir Michael Victor Berry
Wednesday, September 26, 2018 - 4:00pm to 5:00pm

A talk based entirely on pictures. Seas sparkle, sunshine generates rainbows, ships make waves. The explanations of these familiar phenomena are as abstract as elsewhere in physics, but pictures are helpful because in light and waves on water we can often see what we are thinking about. There are other optical phenomena that are not immediately perceived (associated with polarization or fine-scale interference, for example), but even with these we can generate pictures to help our understanding. Poets and novelists, as well as painters, have sometimes represented optical phenomena in ways...

Faster than fourier (pre)revisited: vorticulture, fractals, escape…

Sir Michael Victor Berry
Monday, September 24, 2018 - 4:30pm to 5:30pm

Band-limited functions can oscillate arbitrarily faster than their fastest Fourier component over arbitrarily long intervals: they can ‘superoscillate’. In physics, this counterintuitive mathematical phenomenon is associated with almost-destructive interference, and occurs near phase singularities in optics and on the world’s ocean tides; and it is associated with quantum weak measurements. Where superoscillations occur, functions are exponentially weak and vulnerable to noise. They are an unexpectedly compact way of representing fractals. Superoscillations in red light can escape as gamma...