This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.
Over the past several years, our understanding of topological electronic phases of matter has advanced dramatically. A paradigm that has emerged is that insulating electronic states with an energy gap fall into distinct topological classes. Interfaces between different topological phases exhibit gapless conducting states that are protected topologically and are impossible to get rid of. In this talk we will discuss the application of this idea to the quantum Hall effect, topological insulators, topological superconductors and the quest for Majorana fermions in condensed matter. We
The existence of a deconfined quantum-critical point [1] between the standard antiferromagnet
and a valence-bond solid in 2D S=1/2 quantum magnets has been controversial, in part due to
An overview will be given of recently discovered connection between asymptotic symmetries in general relativity and soft theorems in quantum field theory together with their implications for the black hole information paradox.
I will first show that a number of persistent astrophysical puzzles, including missing pulsars in the galactic center, fast radio bursts, the abundance of r-process elements, and the type Ia supernova progenitor problem, may all be an emerging signature of dark matter. I will address some theoretical implications and new astrophysical phenomena -- for example "quiet kilonovae" and "r-process donuts" -- associated with this dark matter.
Dark matter is all around us, however its particle physics nature is still mysterious. Searches for dark matter have largely focused on candidates with weak scale interactions to the standard model particles, the so-called WIMP paradigm. However, the parameter space of the WIMP paradigm is becoming increasingly constrained by both the LHC and direct detection experiments. Another possibility that is well motivated both theoretically and observationally is to have a dark sector connected with the visible one via a mediator whose coupling to the visible one is tiny.
The origin and composition of 85% of the matter in the universe is completely unknown. Among several viable options, Weakly Interacting Massive Particles (WIMPs) are motivated dark matter candidates that can be tested by different and complementary search strategies. Crucially, different searches probe WIMP couplings at different energy scales, and such a separation of scales has striking consequences in connecting different experimental probes. This motivates the development of theoretical tools to properly connect the different energy scales involved in constraining WIMP models.
Collisions at the Large Hadron Collider (LHC) are dominated by jets, collimated sprays of particles that arise from quantum chromodynamics (QCD) at high energies. With the remarkable performance of the ATLAS and CMS detectors, jets can now be characterized not just by their overall direction and energy but also by their substructure. In this talk, I highlight the increasingly important role that jet substructure is playing in searches for dark matter and other new physics at the LHC, especially when exploring extreme kinematic regimes involving large Lorentz boosts.
Many-body entanglement can lead to exotic phases of matter beyond conventional symmetry breaking paradigm. Those exotic phases may contain fractionalized quasiparticles and emergent gauge fields. In this talk, I will focus on a wide class of long-range entangled phases—quantum spin liquid. In quantum spin liquids, the spins are entangled in some intricate fashion giving rise to interesting physics such as emergent topological field theory and QED3 theory. I will show in detail how such exotic physics can emerge in simple spin systems.
It is commonly believed that quantum information is not lost in a black hole. Instead, it is encoded into non-local degrees of freedom in some clever way; like a quantum error-correcting code. In this talk, I will discuss how one may resolve some paradoxes in quantum gravity by using the theory of quantum error-correction. First, I will introduce a simple toy model of the AdS/CFT correspondence based on tensor networks and demonstrate that the correspondence between the AdS gravity and CFT is indeed a realization of quantum codes.