This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.
By a celebrated theorem of Jacob Lurie, an extended TQFT is entirely determined by what it assigns to a point. It is natural to ask whether this theorem applies to TQFTs of physical interest. And, if yes, what do these theories assign to a point? In this talk, I will propose an answer for the case of 3-dimensional Chern-Simons theory. I will then
explore the relation to line defects in chiral WZW models, and boundary conditions for full WZW models. At last, I will present a conjectural classification of the above mentioned line defects and boundary conditions.
Laser-cooled trapped ions are among the most versatile experimental platforms for exploring quantum information. In this talk, I will give a brief overview of this system and its capabilities to simulate non-trivial interacting quantum models. Internal states of these ions, such as hyperfine states, constitute well isolated qubit (or spin-1/2) states, with quantum coherence demonstrated up to fifteen minutes. Individual qubits states can be detected by laser beams with near perfection.
The discovery of the Higgs boson at the LHC in 2012 was a watershed in particle physics. Its existence focuses attention on the outstanding questions about physics beyond the Standard Model: is `empty' space unstable? what is the dark matter? what is the origin of matter? what is the explanation for the small masses of the neutrinos? how is the hierarchy of mass scales in physics established and stabilized? what drove inflation?
Black holes of 1 million to 20 billion solar masses have been found at the centers of galaxies.
Conformal Field Theory (CFT) describes the long-distance
dynamics of numerous quantum and statistical many-body systems. The
long-distance limit of a many-body system is often so complicated that
it is hard to do precise calculations. However, powerful new
techniques for understanding CFTs have emerged in the last few years,
based on the idea of the Conformal Bootstrap. I will explain how the
Bootstrap lets us calculate critical exponents in the 3d Ising Model
to world-record precision, how it explains striking relations between
In this talk, I will focus on cosmologies that replace the big bang with a big bounce. I will explain how, in these scenarios, the large-scale structure of the universe is determined during a contracting phase before the bounce and will describe the recent development of the first well-behaved classical (non-singular) cosmological bounce solutions.
Non-Fermi liquids are exotic metallic states which do not support well defined quasiparticles. Due to strong quantum fluctuations and the presence of extensive gapless modes near the Fermi surface, it has been difficult to understand universal low energy properties of non-Fermi liquids reliably. In this talk, we will discuss recent progress made on field theories for non-Fermi liquids.
In recent years, precise cosmological measurements have provided strong evidence for new physics beyond the Standard Model, occurring both in the very early universe and also today. In the near future, large-scale galaxy surveys will open another window on many different areas of physics, including tests of gravity, probes of dark energy, and cosmic inflation. However, interpreting galaxy surveys presents new challenges, because galaxies are sensitive to astrophysics that are unimportant for the cosmic microwave background.
I will argue that the standard model contains a rather strong hint that -- instead of being simply an ordinary continuous 4D manifold -- spacetime is actually the product of a 4D manifold and a certain discrete/finite 6D space (i.e. there are 6D discrete/finite "extra dimensions"). I will introduce this idea and the evidence for it in simple way, and then discuss various outstanding puzzles and future directions.
Tensor networks offer an efficient representation of many-body wave-functions in an exponentially large Hilbert space by exploiting the area law of ground state quantum entanglement. I will start with a gentle introduction to the tensor network formalism. Then I will describe its application to realizing Wilson's renormalization group directly on quantum lattice models (e.g. quantum spin chains), with emphasis on the RG fixed points corresponding to conformal field theories.