Weekly Colloquium

Most weeks during the semester, we host a scholar for a one-day visit. The visit culminates with a public talk on a topic of contemporary physics or astronomy. Students are welcome to these talks, and seniors are required to attend at least nine over the course of a year. Near the end of each semester, honors thesis students give public lectures on their work.   

Our Astronomy program is part of the Five College Astronomy Department, which hosts its own colloquium series Thursdays at 3:45 pm at UMass. 

  • Contact colloquium organizer Rachael Dunphy with any questions about colloquia, or being added to our mailing list.

November 2019

Tue, Nov 5, 2019

Michael Lubell, City College of New York: "Navigating the Maze: How Science and Technology Policy Shape America and the World"

Science and the technologies it has spawned have been the principal drivers of the American economy since the end of World War II. Today, economists estimate that a whopping 85 percent of gross domestic product (GDP) growth traces its origin to science and technology. The size of the impact should not be a surprise, considering the ubiquity of modern technologies.

Innovation has brought us the consumer products we take for granted: smartphones and tablets, CD and DVD players, cars that are loaded with electronics and GPS navigating tools and that rarely break down, search engines like Google and Yahoo, the Internet and the Web, money-saving LED lights, microwave ovens and much more. Technology has also made our military stronger and kept our nation safer. It has made food more affordable and plentiful. It has provided medical diagnostic tools, such as MRIs, CT scanners and genomic tests; treatments for disease and illness, such as antibiotics, chemotherapy, immunotherapy and radiation; minimally invasive procedures, such as laparoscopy, coronary stent insertion and video-assisted thoracoscopy; and artificial joint and heart valve replacements.

None of those technological developments were birthed miraculously. They owe a significant part of their realization to public and private strategies and public and private investments. Collectively the strategies and investments form the kernel of science and technology policy. "Navigating the Maze" is a narrative covering more than 230 years of American science and technology history. It contains stories with many unexpected twists and turns, illustrating how we got to where we are today and how we can shape the world of tomorrow.

Tue, Nov 12, 2019

Eduardo H Da Silva Neto

Despite three decades studying superconductivity in cuprate-based materials, we are still left with an incomplete understanding of how their superconducting state at unexpectedly high temperatures emerges from a “soup” of multiple broken-symmetry phases (i.e. ordered states). Although states of broken translational symmetry (i.e. charge order) were known to exist in some cuprates, only recently have we realized [1,2] that charge order could be the missing piece of the high-Tc puzzle. To understand how charge order fits in the puzzle, we require a suite of new measurements to specifically address: What does the charge order ‘look’ like? Is the charge order, like superconductivity, ubiquitous to all cuprates or just a material-specific accident? Is it helpful or harmful to superconductivity? Which electronic orbitals form the ordered patterns? Is it related to the mysterious pseudogap phase? Do the electron spins participate in the charge order phenomenon?
In this talk, I will discuss how we pushed the limits of scanning tunneling microscopy and spectroscopy (STM/S) and resonant (inelastic) x-ray scattering (R(I)XS) to address some of these questions [2-5]. In particular, I will focus on how STS can be used to ‘take pictures’ of charge order patterns with atomic resolution in solids and how soft RXS has emerged as an extremely sensitive technique to detect charge order in quantum materials.
[1] G. Ghiringhelli, et al. Science 337, 821 (2012).
[2] E. H. da Silva Neto, et al. Science 343, 393 (2014).
[3] E. H. da Silva Neto, et al. Science 347, 282 (2015).
[4] E. H. da Silva Neto, et al. Science Advances 2 (8), e1600782 (2016).
[5] E. H. da Silva Neto, et al. PRB, Rapid Comm. 98, 161114(R) (2018).

Tue, Nov 19, 2019

Andrew A Geraci, Northwestern: “Hunting for Fifth-Forces and Dark Matter with AMO-Based Sensors”

We normally think of large accelerators and massive detectors when we consider the frontiers of elementary particle physics, pushing to understand the universe at higher and higher energy scales. However, several tabletop low-energy experiments are positioned to discover a wide range of new physics beyond the Standard model, where feeble interactions require precision measurements rather than high energies. In high vacuum, optically levitated dielectric nanospheres achieve excellent decoupling from their environment, making force sensing at the zeptonewton level (10-21 N) achievable.

In this talk, I will describe our progress towards using these sensors for tests of the Newtonian gravitational inverse square law at micron-length scales. Optically levitated dielectric objects and optical cavities show promise for a variety of other applications, including searches for gravitational waves and dark matter. Finally, I will discuss the Axion Resonant InterAction Detection Experiment (ARIADNE), a precision magnetometry experiment using laser-polarized 3-He gas to search for a notable dark-matter candidate: the QCD axion.