Since 2002 Perimeter Institute has been recording seminars, conference talks, public outreach events such as talks from top scientists using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities.
Recordings of events in these areas are all available and On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
Accessibly by anyone with internet, Perimeter aims to share the power and wonder of science with this free library.
I will discuss entanglement negativity, an entanglement measure for mixed quantum states, in many-body systems,
including lattice quantum systems and quantum field theories.
I will also discuss the possible holographic dual description of entanglement negativity in field theories and tensor networks.
The shape deformation of conformal defects is implemented by the displacement operator. In this talk we consider superconformal defects and we provide evidence of a general relation between the two-point function of the displacement and the one-point function of the stress tensor operator. We then discuss the available techniques for the computation of this one-point function. First, we show how it can be related to a deformation of the background geometry.
The out-of-time-ordered correlator (OTOC) and entanglement are two physically motivated and widely used probes of the ``scrambling'' of quantum information, which has drawn great interest recently in quantum gravity and many-body physics. By proving upper and lower bounds for OTOC saturation on graphs with bounded degree and a lower bound for entanglement on general graphs, we show that the time scales of scrambling as given by the growth of OTOC and entanglement entropy can be asymptotically separated in a random quantum circuit model defined on graphs with a tight bottleneck.
The g-theorem is a prominent example of C-theorems in two-dimensional boundary CFT and the extensions are conjectured to hold in higher-dimensional BCFTs. On the other hand, much less is known for C-theorems in a CFT with conformal defects of higher codimensions. I will investigate the entanglement entropy across a sphere and sphere free energy as a candidate for a C-function in DCFT, and show they differ by a universal term proportional to the vev of the stress tensor. Based on this relation, I will propose to use the sphere free energy as a C-function in DCFT.
I will review recent results concerning a general class of parametric BPS Wilson loops in ABJM theory. In particular, I will present a proposal for their exact quantum expression in terms of a parametric Matrix Model and discuss their role in the exact calculation of physical quantities like the Bremsstrahlung function and in testing the AdS4/CFT3 correspondence.
We observe that boundary correlators of the elementary scalar field of the Liouville theory defined on rigid AdS2 background are the same as the correlators of the chiral stress tensor of the Liouville CFT on the complex plane restricted to the real line. The same relation generalizes to the conformal abelian Toda theory: correlators of Toda scalars on AdS2 are directly related to those of the chiral W-symmetry generators in the Toda CFT and thus are essentially controlled by the underlying infinite-dimensional symmetry.
I will overview recent results on the defect CFT corresponding to Wilson loop operators in N=4 SYM theory. In particular, I will review the calculation of defect correlators at strong coupling using the AdS2 string worldsheet, and I will present exact results for correlation functions in a subsector of the defect CFT using localization. I will also discuss a defect RG flow from the BPS to the ordinary Wilson loop, which can be used to provide a test of the "defect F-theorem" for one-dimensional defects.
In this talk, I will briefly discuss the construction of semiclassical 1/2-BPS boundary conditions and duality interfaces in 3d N=2 theories, following work with T. Dimofte and D. Gaiotto. Then, I will sketch some mathematical applications of these codimension-1 defects to the geometry of triangulated 4-manifolds and chiral algebras, based on work with T. Dimofte and building off related advances by Gadde, Gukov, and Putrov.
A four-dimensional abelian gauge theory can be coupled to a 3d CFT with a U(1) symmetry living on a boundary. This coupling gives rise to a continuous family of boundary conformal field theories (BCFTs) parametrized by the gauge coupling \tau and by the choice of the CFT in the decoupling limit. Upon performing an Electric-Magnetic duality in the bulk and going to the decoupling limit in the new frame, one finds a different 3d CFT on the boundary, related to the original one by Witten's SL(2, Z) action.
Check back for details on the next lecture in Perimeter's Public Lectures Series