# All Videos

In his talk, Robert Griffiths (CMU) wonders "where was the photon?" in a nested Mach-Zehnder interferometer.

He walks us along the path taken by a wave passing through a beam splitter before reaching a detector with pedagogy and humor!

Liang Fu (MIT) talks about recent developments in the control of Majorana fermions using the charging energy in mesoscopic systems.

In his talk, he addresses the following questions: can one probe the topological properties of Majorana Fermions in the solid state, specifically their non-locality as two Majorana Fermions share a single state. Then, can one use those topological properties in the field of quantum computation.

He then proceeds to demonstrate the latest developments in the entangled ares of theoretical physics, quantum information, and quantum materials.

The PQI2016 Public Lecture was given by Prof. Michel Devoret of Yale University. In his talk entitled “The Quest for the Robust Quantum Bit”, Devoret presents the progress of his group towards the conservation of quantum information via the use of “CAT-states”, a wink and a nudge to Schrodinger’s cat in its superposition of alive and dead states.

He describes the outstanding research carried out in his lab and the future considerations of his newly founded company, Quantum Circuits, Inc., which are taking us one step closer to the advent of the ultimate super computer: the quantum computer.

Randy Feenstra (CMU) discusses the use of both first-principles computational methods and low-energy electron microscopy in the investigation of two-dimensional transition-metal dichalcogenide materials as potential candidates for interlayer tunneling devices.

He uses the former to realistically estimate the values of tunneling currents and the latter to characterize the layers. He discusses as well the progress towards fabricating a full interlayer tunneling device.

Ken Jordan (Pitt) shows how electronic correlation in a system can be taken into account via a Drude oscillator.

First he demonstrates Feyman's "conjecture", which states that two atoms at long distance acquire permanent dipoles due to dispersion interactions. The dipole and atomic force both vary as R-7.

He shows that the permanent dipole on an atom is induced by the coupling of the instantaneous dipole on the other atom and its hyperpolarizability, and that, as predicted by Feynman, the two negative ends of the dipoles point toward each other.

David Pekker's (Pitt) talk is about emergent conserved quantities in strongly disordered matter.

He explains how the conventional wisdom that states that interacting systems are their own heat baths breaks down via the spontaneous appearance of local quantum numbers and describes the renormalization method he used to find them. This approach, called a Wegner flow, could be a foundation for the analytical theory of many-body localization transitions.

Vincent Sokalksi (CMU) presents his new study on the energetic molding of fermion-like magnetic bubbles.

He first introduces the Dzyaloshinskii-Moriya interaction (DMI), which is the origin of skyrmions and magnetism, and then proceeds to describe how to measure this interaction.

He shows, using a Wolff construction, how DMI impacts the growth behavior of magnetic bubbles.

In her talk, Grace Xing (Cornell University) describes the recent progress accomplished in her group in the field of 2D materials towards the fabrication of Thin-Tunneling Field-Effect Transistor (TFET) devices, where Thin stands for Two-dimensional Heterojunction Interlayer Tunnel.

Indeed, she describes how the group has been able to observe a 40 mV/decade subthreshold slope in 2D materials, which is an experimental first.

Sean Garrett-Roe (Pitt) presents the collaborative work fostered by PQI, between his experimental lab and the theoretical group of Daniel Lambrecht.

He describes the use of ultra fast spectroscopic techniques to provide molecular details about the interaction and dynamics of a molecule with its environment in the framework of CO2 capture in ionic liquids. The group uses the anti-symmetric stretch of the CO2 molecule as a probe to investigate the intermolecular interactions that lead to bulk properties.

In his talk, entitled "Bridging QM and Chemical Intuition", Daniel Lambrecht (Pitt) shows how quantum mechanics can inform conceptual thinking in chemistry.

He walks us through a well defined procedure that allows the calculation of "chemical" quantities that are not observables, for example the notion of charge transfer. The approach he describes is a flavor of energy decomposition analysis, and it can be applied to the calculation of properties such as vibrational spectra as demonstrated in their study.