Talks

The Fermi Gamma-ray Space Telescope has provided unique insights into the Universe's biggest explosions over the past 12 years. With thousands of gamma-ray bursts (GRBs) detected by the Gamma-ray Burst Monitor (GBM) and hundreds by the Large Area Telescope (LAT), we have learned about the broad properties of the populations of these events and got unique insights into their emission mechanisms, environment, and physical properties. In this seminar, I'll review highlights of GRB science from the Fermi mission at low (keV) and high (GeV) energy, as well as the recent discovery of very-high (TeV) energy emission from GRB 180720B and GRB 140114C observed by the Cherenkov Telescopes of the H.E.S.S. and MAGIC experiments, respectively

The velocity of a gravitational wave (GW) source provides crucial information about its formation and evolution processes.

Previous studies considered the Doppler effect on the phase of GWs as a potential signature of a time-dependent velocity of the source. However, the Doppler shift only accounts for the time component of the wave vector, and in principle motion also affects the spatial components. In my talk I discuss the latter effect, known as “aberration” for light, for GWs and how it affects the waveform modeling of an accelerating source. I show that the additional aberrational phase shift could be detectable in two astrophysical scenarios, namely, a recoiling binary black hole (BBH) due to GW radiation and a BBH in a triple system.

Further, I discuss how adding the aberrational phase shift in the waveform templates could significantly enhance the detectability of moving sources.

Given a vector in a representation, can it be distinguished from zero by an invariant polynomial? This classical question in invariant theory relates to a diverse set of problems in mathematics and computer science. In quantum information, it captures the quantum marginal problem and recent bounds on tensor ranks. We will see that the general question can be usefully thought of as an optimization problem and discuss how this perspective leads to efficient algorithms for solving it.

We compute the path integral of three-dimensional gravity with negative cosmological constant on spaces which are topologically a torus times an interval. These are Euclidean wormholes, which smoothly interpolate between two asymptotically Euclidean AdS3 regions with torus boundary. From our results we obtain the spectral correlations between BTZ black hole microstates near threshold, as well as extract the spectral form factor at fixed momentum, which has linear growth in time with small fluctuations around it. The low-energy limit of these correlations is precisely that of a double-scaled random matrix ensemble with Virasoro symmetry. Our findings suggest that if pure three-dimensional gravity has a holographic dual, then the dual is an ensemble which generalizes random matrix theory.

In this talk, I will discuss emergent criticality in non-unitary random quantum dynamics. More specifically, I will focus on a class of free fermion random circuit models in one spatial dimension. I will show that after sufficient time evolution, the steady states have logarithmic violations of the entanglement area law and power law

correlation functions. Moreover, starting with a short-range entangled many-body state, the dynamical evolution of entanglement and correlations quantitatively agrees with the predictions of two-dimensional conformal field theory with a space-like time direction. I will argue that this behavior is generic in non-unitary free quantum dynamics with time-dependent randomness, and show that the emergent conformal dynamics of two-point functions arises out of a simple" nonlinear master equation".

COVID-19 is a mysterious disease associated with a large number of unanswered questions. 

In this talk we review what is currently known, what is still a mystery and highlight some of our recent work on the role of climate, blood type and vaccinations on the transmission of the disease and on the extent of "dark infections", the asymptomatic and untested proportion of infections. We end with a list of open research questions that may be amenable to techniques from physics and data science.