This series consists of talks in the area of Quantum Fields and Strings.
Motivated by recent interesting holographic results, several attempts have been made to study complexity ( rather " Circuit Complexity") for quantum field theories using Nielsen's geometric method. But most of the studies so far have been limited to free quantum field theory. In this talk we will take a baby step towards understanding the circuit complexity for interacting quantum field theories. We will consider \lambda \phi^4 theory and discuss in detail how to set up the computation perturbatively in coupling.
Using knowledge about the spectrum of operators in N=4 SYM, consistency of OPE, and analytic bootstrap techniques, I will obtain 1- loop corrections for 4-pt functions of single particle half-BPS operators of IIB supergravity on AdS_5\timesS^5. Along the way, I will discuss a general formula for the leading anomalous dimension of all double-trace operators in the supergravity regime.
Seminar given remotely.
Recently I pointed out that reconstruction of interior operators can be interpreted as the Hayden-Preskill recovery. Building on this observation, I will propose a resolution of the firewall puzzle by describing a state-independent reconstruction of interior operators which does not lead to the non-local signaling.
We show how the extended thermodynamics of hyperbolic black holes in AdS describes features of quantum information measures in quantum field theory, and discuss prospects for making further connections. In particular, the second law of thermodynamics is seen in this context to map to the generalized Zamolodchikov c-theorem, connecting these two firmly for the first time. Some projects for getting further lessons and perhaps new tools from these connections (perhaps using holographic heat engines) are outlined.
We consider implications of superrotations as an asymptotic symmetry of asymptotically flat spacetimes. Beginning with a review of the rich structure of interconnections between soft theorems, asymptotic symmetries, and memory effects, we describe the superrotation iteration. The subleading soft graviton theorem can be cast as a Ward identity for this asymptotic symmetry in 4D, and also as one for the stress tensor of a putative CFT2. We detail the change of scattering basis motivated by this asymptotic symmetry and discuss recent progress.
In gauge theories, there is an inherent tension between locality and gauge invariance. This is precisely expressed by the failure to factorize the physical Hilbert space into local tensor products.
Abstract TBA
The two-point functions <O^n(x) Obar^n(y)> for generator O of Coulomb branch chiral rings in D=4 N=2 SCFT will be determined universally to all orders in 1/n by the theory's a-anomaly.
The calculation will be done using the method of large-charge expansion presented in [1706.05743]; the absence of F-terms in the (R-charge)^(-1) expansion of the effective action ensures this universality.
I will also comment on the non-universal and non-perturbative corrections to the two-point functions whose leading piece was numerically shown to go as O(exp(-sqrt(n))).
In this talk I will review the results of recent work in collaboration with Cecilia De Fazio, Benjamin Doyon and István M. Szécsényi. We studied the entanglement of excited states consisting of a finite number of particle excitations. More precisely, we studied the difference between the entanglement entropy of such states and that of the ground state in a simple bi-partition of a quantum system, where both the size of the system and of the bi-partition are infinite, but their ratio is finite.