Calendar

In my talk I discuss traversable wormholes in four and two dimensions.

Based on arXiv: 1807.04726 and 1912.03276

via Zoom Video Conferencing:  https://harvard.zoom.us/s/977347126

Zoom: https://harvard.zoom.us/j/94717938264

Interference is an essential part of quantum mechanics. However, an important class of Hamiltonians considered are those with “no sign problem”, where all off-diagonal matrix elements of the Hamiltonian are non-negative. This means that the ground state wave function can be chosen to have all amplitudes real and positive. In a sense, no destructive interference is possible for these Hamiltonians so that they are “almost classical”, and there are several simulation algorithms which work well in practice on classical computers today. In this talk, I’ll discuss what happens when one considers adiabatic evolution of such Hamiltonians, and show that they still have some power that cannot be efficiently simulated on a classical computer; to be precise and formal, I’ll show this “relative to an oracle”, which I will explain. I’ll discuss implications for simulation of these problems and open questions.

Zoom: https://harvard.zoom.us/j/779283357

More than 10 years ago, I showed that non-supersymmetric QCD with adjoint fermions admits a (non-thermal) compactification on $R^3 \times S^1$ where non-perturbative gauge dynamics becomes calculable. The mass gap, linear confinement and discrete chiral symmetry breaking are sourced by magnetic bions, which are correlated monopole-instanton anti-instanton pairs which have non-vanishing magnetic charge but have zero topological charge. This construction led to the idea of the double-trace deformation of pure Yang-Mills theory on $R^3 x S^1$, which is continuously connected to pure YM on $R^4$ in the sense of continuity of all gauge invariant order parameters. It turns out that all qualitative non-perturbative properties of deformed YM theory are in agreement with all of our non-perturbative expectations concerning pure YM theory. Over the last year, numerical simulations have shown that the topological susceptibility of deformed YM on small $S^1 \times R^3$ are in precise agreement with the numerical results on large $S^1 \times R^3$. Therefore, it is very likely that there is more truth in deformed YM construction than that meets the eye. I will give a lecture style talk on these topics.

Zoom: https://harvard.zoom.us/j/977347126

I will describe two new descriptions of gapped fracton topological order. These descriptions are generic and make minimal modifications to ordinary TQFT in order to obtain fracton physics. The first description constructs a fracton order by embedding a network of topological defects (aka interfaces) within an ordinary topological order, which results in the restricted fracton mobility. The second description takes the continuum limit by viewing the defect layers as infinitesimally separated. This is done by coupling a TQFT, such as BF theory, to a new kind of foliated gauge field. The first description is based on arXiv:2002.05166, while the second is based on a forthcoming work.

Zoom: https://harvard.zoom.us/j/977347126