Colloquium Preview Fall 2020
Date: October 1, 2020
Speaker: Richard Taylor, Dept. Head, UO Physics
Title: State of the Department
Date: October 8, 2020
Speaker: Brian J. Smith, UO Physics
Title:Control and Measurement of Quantum Optical Pulses
Abstract: The ability to manipulate and measure the spectral-temporal waveform of optical pulses has enabled a wide range of applications from ultrafast spectroscopy to high-speed communications. Extending these concepts to quantum light has the potential to enable breakthroughs in optical quantum science and technology. However, filtering, amplifying and optical nonlinear interactions often employed in classical pulse shaping and measurement techniques are incompatible with non-classical light. Controlling and efficiently measuring the pulsed mode structure of quantum light requires efficient means to achieve deterministic, unitary manipulation of pulses that preserves fragile quantum coherences. Here an approach to deterministically modify the pulse-mode structure of quantum states of light within an integrated optical platform is presented. The manipulation method is based upon application of both spectral and temporal phase modulation to the wave packet. With this approach we demonstrate deterministic spectral shift and time-lensing of single-photon wave packets through the application of linear and quadratically-varying temporal phase. Furthermore, application of quadratic spectral phase to a short single-photon pulse maps frequency onto time, which enables one to monitor the single-photon spectrum with a fast photon-counting spectrometer. We demonstrate experimentally the application of spectral shear within an interferometer followed by spectrally-resolved detection enables complete characterization of quantum light pulses. These techniques lay the ground for future quantum wavelength- and time-division multiplexing applications and facilitate interfacing of different physical platforms where quantum information can be stored and manipulated.
Date: October 15, 2020
Speaker: Marcelle Soares-Santos, University of Michigan
Title: Cosmology in the era of multi-messenger astronomy with gravitational waves
Abstract: Motivated by the exciting prospect of a new wealth of information arising from the first observations of gravitational and electromagnetic radiation from the same astrophysical phenomena, the Dark Energy Survey (DES) has established a search and discovery program for the optical transients associated with LIGO/Virgo events (DESGW). Using the Dark Energy Camera (DECam), DESGW has contributed to the discovery of the optical transient associated with the neutron star merger GW170817, and produced the first cosmological measurements using gravitational wave events as standard sirens. After three successful observing campaigns, I present, in this talk, an overview of our results and their implications for the emerging field of multi-messenger cosmology with gravitational waves and optical data.
Host: Tien-Tien Yu
Date: October 22, 2020
Speaker: Andrea Liu, University of Pennsylvania
Title: Exploiting the Malleability of Disorder to Design Biologically-Inspired Function
Abstract: The complexity of living systems poses a formidable challenge to physical scientists interested in biology. I will discuss one theoretical approach towards gaining possible insight into biological phenomena: to design systems to exhibit similar phenomena. To do so, we start with systems with complex energy/cost landscapes, which have far more variation in their properties than those with simple ones. This natural variation can be pushed even further by design, allowing us to tune in properties inspired by those common in living matter, such as the ability of proteins (e.g. hemoglobin) to change their conformations upon binding of an atom (oxygen) or molecule, or the ability of the brain’s vascular network to send enhanced blood flow and oxygen to specific areas of the brain associated with a given task. We create ensembles of systems designed for a given task to gain new insight into the relation between microscopic structure and function that may help us to understand living systems.
Host: Eric Corwin
Date: October 29, 2020
Speaker: Philip W. Phillips, University of Illinois
Title: Does Noether’s Second Theorem Imply Hidden Extra Dimensions in the Cuprates?
Abstract: For the past 30 years, the transport properties in the unusual metallic phase seen in the cuprate superconductors and many other quantum critical metals, have defied an explanation in terms of the standard building blocks of modern physics — particles with local interactions and conservation laws. A recent proposal suggests that all of the properties of such `strange metals’ can be understood if the current has an anomalous dimension not determined simply by dimensional analysis. My talk will focus on trying to understand this claim. To demystify this claim, I will first show that even in the standard formulation of electricity and magnetism, there is an extra degree of freedom, which has remained unnoticed until now, that can allow, in principle, for the current to have any allowable dimension. This extra degree of freedom is a consequence of Noether’s Second Theorem. However, I will show that the only quantum theories to date which exhibit such odd behaviour are holographic models that are derived from a gravity theory that lives in higher dimensions. The existence of currents having anomalous dimensions, a direct probe of the existence of extra `hidden’ dimensions, can be tested with the Aharonov-Bohm effect. I will describe this effect and its potential impact for unlocking the secret of the strange metal in the cuprates.
Host: Dietrich Belitz
Date: November 5, 2020
Speaker: Sabetta Matsumoto, Georgia Tech
Title: Twisted Topological Tangles or: the knot theory of knitting
Abstract: Imagine a 1D curve, then use it to fill a 2D manifold that covers an arbitrary 3D object – this computationally intensive materials challenge has been realized in the ancient technology known as knitting. This process for making functional materials 2D materials from 1D portable cloth dates back to prehistory, with the oldest known examples dating from the 11th century BCE. Knitted textiles are ubiquitous as they are easy and cheap to create, lightweight, portable, flexible and stretchy. As with many functional materials, the key to knitting’s extraordinary properties lies in its microstructure.
At the 1D level, knits are composed of an interlocking series of slip knots. At the most basic level there is only one manipulation that creates a knitted stitch – pulling a loop of yarn through another loop. However, there exist hundreds of books with thousands of patterns of stitches with seemingly unbounded complexity.
The topology of knitted stitches has a profound impact on the geometry and elasticity of the resulting fabric. This puts a new spin on additive manufacturing – not only can stitch pattern control the local and global geometry of a textile, but the creation process encodes mechanical properties within the material itself. Unlike standard additive manufacturing techniques, the innate properties of the yarn and the stitch microstructure has a direct effect on the global geometric and mechanical outcome of knitted fabrics.
Host: Jayson Paulose
Date: November 12, 2020
Speaker: Kirill Shtengel , University of California
Host: Saumya Biswas
Date: November 19, 2020
Speaker: Cacey Bester, Swarthmore College
Host: Eric Corwin
Date: November 26, 2020