Colloquium Archives

James Battat, Wellesley College

Title: Testing Fundamental Physics by Ranging to the Moon (Video)

Abstract: Lunar Laser Ranging has enabled comprehensive, precision tests of gravity for nearly 50 years.  I will discuss my work on the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO), which achieves millimeter-precision measurements of the lunar orbit.  Such high-precision measurements, coupled with decades of archival data, provide exquisite constraints on gravitational physics. In fact, LLR currently provides the tightest bounds on the strong equivalence principle, the inverse square law of gravity at relevant scales, gravitomagnetic interactions, the time-rate of change of G and Lorentz symmetry in the gravitational sector.

Peter Cornillion

Title: Physical Oceanography - Perspective, Fundamentals & Cool Stuff (Video)

Abstract: This presentation will begin by comparing progress in physical oceanography with that in particle physics, highlighting some of the aspects that make physical oceanography difficult to study.  This will be followed with a brief introduction to the fundamental concepts in physical oceanography – done in the context of how the oceans compare with a bathtub. The third portion of the presentation will examine satellite-derived observations of the ocean with examples of applications of these observations ranging from the global scale to what is referred to as the submesoscale. Specific examples will be measurement of the evolution of the mean temperature of the ocean from thebottom to within 2000m of the surface; large zonal bands of sea surface temperature gradient, and; astounding surface temperature gradients in the vicinity of large eddies that have detached from the Gulf Stream.

David Hall, Amherst College

Title: Tying Knots in a Quantum Fluid (Video)

Abstract: Knots are familiar entities that appear at a captivating nexus of art, technology, mathematics,and science. Following a lengthy period of theoretical investigation and development, they have recently attracted great experimental interest in contexts ranging from knotted DNA and nanostructures to vortex knots in classical fluids. In this talk I will discuss the first controlled creation and detection of knot solitons in a quantum fluid, a spinor Bose-Einstein condensate. Our observations establish an experimental foundation for future studies of the stability, dynamics, applications, of knot solitons within quantum systems. The knot solitons themselves provide a striking experimental demonstration of the celebrated Hopf fibration, which unites many seemingly unrelated physical phenomena.

Maxim Olshanii, University of Massachusetts, Boston

Title: The Tonks-Girardeau Gas: Then, Now, and in the Future (Video)

Abstract: In this presentation, I will review the 55+ years of progress passed since Marvin Girardeau found, in 1960, a full nonperturbative solution for the quantum hard-core bosons, further extended to the finite strength interactions in 1963 by Lieb and Liniger. This discovery brought the multi-(all the way to infinite-)dimensional reflection groups to many-body physics, ignited experimental and theoretical studies of confined scattering, and  led to a new direction in experiments with ultracold quantum gases. Recent successes in control of effective particle masses in optical lattices allow us to bring new exotic reflection symmetries to the game. I will conclude with a description of a new solvable problem of four confined mass 6:2:1:3 particles associated with the symmetries of an octacube---a unique to four spatial dimensions Platonic solid, with no three-dimensional analogues.    

Alexey Gorshkov, Joint Quantum Institute

Title: Harnessing Quantum Systems with Long-Range Interactions (Video)

Abstract: Many AMO (atomic, molecular, and optical) systems, such as Rydberg atoms, polar molecules, and ions, exhibit long-range interactions decaying as a power-law with distance. In this talk, we will discuss the effects of long-range interactions on the speed of information propagation in quantum systems, with implications for entanglement growth, thermalization, quantum communication, quantum computing, and properties of gapped ground states. We will also show that long-range interactions can affect the properties of topological phases and can mask the dimensionality of the system, allowing for spontaneous breaking of a continuous symmetry in one dimension.