Colloquium
Unless otherwise noted, the physics colloquia are held in Room 307 of the Science and Engineering Research Facility. Refreshments are served at 3:00 p.m. with the talk following at 3:30.
January 13 |
Arthur Hatton |
Student Mental Health Tips, and Introduction to the Counseling Center |
|
January 20 |
MLK Holiday/No Colloquium |
|
|
January 27 |
Rachel Yohay |
||
February 3 |
|||
February 10 |
Daniel Phillips |
Knowing What You Don’t Know: Nuclear Physics, Effective Field Theory, and Uncertainty Quantification |
|
February 17 |
John Martinis |
Quantum Supremacy using a Programmable Superconducting Processor |
|
February 24 |
Joe Paddison |
||
March 2 |
Florian Neukart |
||
March 9 |
Jian-Min Zuo |
Electron Diffraction, from Quantum Mechanics to Imaging Proteins and FinFET Devices |
|
March 16 |
Spring Break/No Colloquium |
|
|
March 23 |
CANCELLED |
|
|
March 30 |
CANCELLED |
|
|
April 6 |
Kelly Holley-Bockelmann |
|
|
April 13 |
Qi Li |
|
|
April 20 |
Honors Day |
|
|
Student Mental Health Tips, and Introduction to the Counseling Center
Dr. Arthur Hatton will offer some information about student mental health from both empirical research and experience working as a university staff psychologist. This will include the role of values and mindfulness in coping with stress, tips on better sleep, impostor syndrome, and general information about the Student Counseling Center.
Searches for Exotic Higgs Decays at CMS
Although the 125 GeV Higgs scalar displays spin, parity, and fermionic and bosonic couplings consistent with those predicted by the Standard Model (SM), constraints on its branching ratio to invisible or non-SM final states are only at the 20-30% level. Direct searches for Higgs decays to invisible or non-SM final states offer further insights into the structure of the Higgs sector, specifically whether it consists of the single doublet of the Standard Model, or multiple doublets as proposed by many theories that extend the Standard Model. In this talk, I will present recent results on searches using data collected by the Compact Muon Solenoid (CMS) detector for Higgs decays to non-SM final states, focusing on decays that proceed via new light Higgs states. Along with general search strategies and interpretations of the current data in terms of two-Higgs-doublet models, dedicated methods for reconstructing low-transverse-momentum and boosted particles characteristic of such decays will be discussed.
Neutrinos: From Idea to Discovery to Precision Measurements
The discovery of neutrino oscillations opened new windows for the study of neutrino physics. In this talk, I will present the history and importance of neutrino physics, concentrating on neutrinos produced by accelerator. Specifically, I will give an overview of the neutrino physics program at Fermilab and the remaining questions for the neutrino physics. In order to answer the open questions in neutrino physics, it is critical that we understand neutrino interactions and nuclear effects on these interactions extremely well. I will highlight recent cross section measurements and remaining challenges to understand neutrino interactions.
Knowing What You Don’t Know: Nuclear Physics, Effective Field Theory, and Uncertainty Quantification
For almost a century physicists have devoted intense attention to teasing out the nature of the nuclear force. But there remains much that we do not know about the way neutrons and protons interact, and the way that they come together to form nuclei. In this talk I will show how two tools–effective field theory and Bayesian probability theory—can provide quantitative assessments of the impact of the things that we don’t know about nuclear physics on experimental observables.
Quantum Supremacy using a Programmable Superconducting Processor
The promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor. A fundamental challenge is to build a high-fidelity processor capable of running quantum algorithms in an exponentially large computational space. Here we report the use of a processor with programmable superconducting qubits to create quantum states on 53 qubits, corresponding to a computational state-space of dimension 253 (about 1016). Measurements from repeated experiments sample the resulting probability distribution, which we verify using classical simulations. Our Sycamore processor takes about 200 seconds to sample one instance of a quantum circuit a million times—our benchmarks currently indicate that the equivalent task for a state-of-the-art classical supercomputer would take approximately 10,000 years. This dramatic increase in speed compared to all known classical algorithms is an experimental realization of quantum supremacy for this specific computational task, heralding a much-anticipated computing paradigm.
Understanding Spin Liquids at the Nanoscale
Cool most materials to low enough temperatures, and eventually they become solids. Most magnetic materials behave in a similar way: at low enough temperatures, the magnetic moments condense into an ordered state. My talk will explore magnets that defy this expectation, and instead remain in magnetically-disordered “spin liquid” states to the lowest measurable temperatures. Spin liquids are exciting because of their ability to host new states of matter driven by the interplay of geometry and quantum fluctuations, which stimulate theoretical understanding. In my talk, I will show how neutron-scattering experiments and atomistic modeling techniques allows us to visualize and understand spin-liquid states at the nanoscale. I will present experimental results that reveal exotic magnetic states in a spin-liquid material in which ordering is eventually driven by emergent degrees of freedom. I will conclude by exploring future directions in the study of spin liquids and conceptually-related materials.
Early Quantum Computing Applications in Industry
With the computers we use today, some of the most important problems will never be solved, among these simulated chemistry, drug discovery, transportation, and artificial intelligence. Practical quantum computers herald a new era in information technology, and it’s happening right now. In the industry, we must be aware of it, understand why and when quantum computers are more powerful than classical computers, and develop knowledge about architectures, algorithms, and programming languages. It’s an exciting field, of which it is clear that despite the progress made, many hurdles still have to be taken. The audience will understand the potential of near-term quantum computers and learn about their strengths and weaknesses in the most practical way.
Electron Diffraction, from Quantum Mechanics to Imaging Proteins and FinFET Devices
Electrons diffract like X-rays and neutrons, except that the electron wavelength is very small (of the order of a few picometers), and the electron scattering cross-section is much larger, about a million times that of X-rays. Inside a transmission electron microscope (TEM), the electron beam can be focused down to < 1 Å in diameter with the current reaching hundreds of picoamps (1 pA = 6.3x106 e/s), so the scattering power of an electron beam is larger than that of a synchrotron. Since electron diffraction was discovered by Davisson and Germer, and Thomson and Reid, in 1927, transmission electron diffraction and the related electron imaging have developed into powerful tools for the analysis of materials, such as proteins and transistor devices.
This talk will introduce the basic quantum property of electrons, that is coherence, the manifestation of coherence, that is diffraction, and how the combination of electron coherence with fast electron detectors has made electron diffraction an exciting development story for the coming decade.