Talks

A preponderance of astronomical evidence suggests that the galaxy is filled with dark matter. Despite knowing remarkably little about what this dark matter is, we expect that it is not composed of ordinary matter. Though we have spent 30 years expecting that it may be related to pressing open problems in fundamental physics, a heroic experimental program has shown that dark matter is even more elusive than we had initially imagined. On February 28, University of California Riverside faculty member Flip Tanedo will discuss how we got things so wrong, why we can be optimistic about the future, and what it means to “do physics” on something where the only thing we really know is that it probably exists. Flip Tanedo spends his time thinking about dark matter. He grew up in Los Angeles and fell in love with physics after reading The Physics of Star Trek. This carried into degrees in mathematics and physics at Stanford, Cambridge, Durham, and a Ph.D at Cornell. After a postdoc at UC Irvine, he is currently faculty at UC Riverside where he is often covered in a layer of chalk dust.

Light bosons, including light axions, dark photons, and dilaton/moduli, are well motivated extensions to the Standard Model of particle physics and intriguing dark matter candidates. Much progress has been made in recent years in both astrophysical and lab searches for these light bosons with the understanding that these light bosons act like weak classical waves which permeate the space we occupy. 

In this talk, I will discuss some novel phenomenon of light bosons in the dark sector, based on important in medium effects of these particles. I will show how to take advantage of medium effects of the photon to optimize searches for these light bosons with data coming from cosmic microwave background (CMB) experiments, and improve sensitivity to light dark photons and axions by orders of magnitude. I will also show how thinking of dark photon as weak classical waves breaks down during production of light bosons in both early and late universe, when gauged strings are produced in an event we call the string Bosenova, as well as the resulting observable consequences.

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Minimizing the energy of a many-body system is a fundamental problem in many fields. Although we hope a quantum computer can help us solve this problem better than classical computers, we have a very limited understanding of where a quantum advantage may be found. In this talk, I will present some recent theoretical advances that shed light on quantum advantages in this domain. First, I describe rigorous analyses of the Quantum Approximate Optimization Algorithm applied to minimizing energies of classical spin glasses. For certain families of spin glasses, we find the QAOA has a quantum advantage over the best known classical algorithms. Second, we study the problem of finding a local minimum of the energy of quantum systems. While local minima are much easier to find than ground states, we show that finding a local minimum under thermal perturbations is computationally hard for classical computers, but easy for quantum computers.

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