Seminar

Fractons: A New Type of Particle

Speaker(s): 
Michael Pretko
Dates: 
Friday, August 14, 2020 - 12:00pm

A fracton is an unusual new type of emergent quasiparticle found in various condensed matter systems.  Fractons are characterized by a set of mobility restrictions, which force isolated fractons to be strictly immobile, while certain bound states of fractons remain free to move.  This behavior leads to a variety of unusual phenomenology, such as non-ergodic and gravitational behavior, and may lead to advances in quantum memory storage.  In this talk, I will give a broad overview of the field of fractons, including both introductory material and recent advances.  I will describe the basics...

Antisymmetry: Fundamentals and Applications

Speaker(s): 
Venkat Gopalan
Dates: 
Thursday, September 17, 2020 - 4:00pm

Symmetry is fundamental to understanding our physical world.  An antisymmetry operation switches between two different states of a trait, such as two time-states, position-states, charge-states, spin-states, chemical-species etc.   This talk will cover the fundamental concept of antisymmetry, with brief mentions of two well-established antisymmetries, namely spatial inversion in point groups and time reversal. Then it will introduce two new ones, namely, distortion reversal and wedge reversion.  The distinction between classical and quantum mechanical descriptions of time reversal will be...

Rings and tunnel junctions: Quantum mechanics on a circle

Speaker(s): 
Arthur Davidson
Dates: 
Thursday, September 10, 2020 - 4:00pm

We show by standard quantum principles that two circuits, a small tunnel junction and a small metal loop with an electron, are related by a gauge transformation. We show further that this same transform prevents momentum eigen functions from having gauge invariant de Broglie wave lengths around a ring. Thus persistent current on a metal ring and the Coulomb blockade on a small tunnel junction seem to be the same dynamical theory based on discontinuous Bloch waves on the perimeter of a circle. This is historically an area of simple quantum circuits where the principle of gauge invariance...

Operator Mechanics: A new form of quantum mechanics without waves or matrices

Speaker(s): 
James Freericks
Dates: 
Thursday, September 3, 2020 - 4:00pm

Quantum mechanics was created with the matrix mechanics of Heisenberg, Born, and Jordan. Schroedinger's wave mechanics shortly followed and allowed for simpler and more powerful calculations. Both Pauli and Dirac introduced a formulation of quantum mechanics based on operators and commutation relations, but it was never fully developed in the 1920's. Instead, Schroedinger formulated the operator approach with his factorization method, which later was adopted by the high-energy community as supersymmetric quantum mechanics.  In this talk, I will explain how one can formulate nearly all of...

Energy Infrastructure Sensing Technologies and Opportunities for Quantum

Speaker(s): 
Paul Ohodnicki
Dates: 
Thursday, September 24, 2020 - 4:00pm

An overview will be presented of some emerging platforms that are relevant for energy infrastructure sensing applications including both optical fiber and passive wireless technologies.  Example motivating applications will be presented including grid modernization, energy resource recovery and transport, and power generation, along with an overview of existing and future sensing technologies under investigation.  A specific emphasis will be placed upon opportunities and limitations in such applications for quantum materials and quantum sensing concepts to enhance capabilities of current...

Anatomy of a Photonic QPU

Speaker(s): 
Eric Johnston
Dates: 
Tuesday, May 19, 2020 - 12:30pm

In building a full-scale QPU, problems of decoherence, scaling, manufacturability, and networking can be solved by using photons as the computational qubits. This also causes some interesting new problems, such as how to wrangle them. Starting with the notation from the Octopus Book, we'll go a bit further, to look at ridiculously-complicated graph states and measurement-based computation. Then we'll go much further, outlining a rough design for a scalable, fault-tolerant photonic QPU.

Bio: Eric R. Johnston ("EJ") (U.C. Berkeley EECS '92) is co-...

POSTPONED: Rings and tunnel junctions: Quantum mechanics on a circle

Speaker(s): 
Arthur Davidson
Dates: 
Thursday, April 2, 2020 - 4:00pm

We show by standard quantum principles that two circuits, a small tunnel junction and a small metal loop with an electron, are related by a gauge transformation.  We show further that this same transform prevents momentum eigenfunctions from having gauge invariant de Broglie wave lengths around a ring. Thus persistent current on a metal ring and the Coulomb blockade on a small tunnel junction seem to be the same dynamical theory based on discontinuous Bloch waves on the perimeter of a circle. This is historically an area of simple quantum circuits where the principle of gauge invariance...

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