Time: 2pm

Location: 2N36

Title: TBA

# Events

Time: 2pm

Location: 2N36

Title: TBA

Time: 2pm

Location: 2N36

Title: TBA

Time: 2pm

Location: 2N36

Title: TBA

Time: 2pm

Location: 2N36

Title: TBA

Time: 2pm

Location: 2N36

Title: TBA

Time: 2pm

Location: 2N36

Title: Entanglement, Gravity, and Quantum Error Correction

Abstract: Over the last few years it has become increasingly clear that there is a deep connection between quantum gravity and quantum information. The connection goes back to the discovery that black hole entropy is given by the horizon area. I will present evidence that this is only the tip of the iceberg, and prove that a similar area law applies to more general Renyi entanglement entropies. Furthermore, I will provide quantum corrections to the area law and use it to address a longstanding problem in quantum gravity: what region of the dual spacetime is described by a subregion in a holographic theory? The answer to this question lies in a new perspective that I will advocate: holography is a quantum error correcting code.

Time: 2pm

Location: 2N36

Title: TBA

Time: 2pm

Location: 2N36

Title: **Shaving off Black Hole Soft Hair**

Abstract: After recalling a definition of a black hole "hair" we explain why the only interesting hairs are those that are also remnants. Next, we will examine a recent proposal by Hawking, Perry and Strominger, who suggest that soft photons and soft gravitons can be regarded as black hole hairs that may be relevant to the black hole information paradox. We will make use of factorization theorems for infrared divergences of the S-matrix to argue that, by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S-matrix becomes essentially trivial, in the sense that the information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta.

Time: 2pm

Location: 2N36

Title: Reinventing the wheel: an effective theory approach to dissipative spinning objects.

Abstract: In this talk, I will show how effective field theory techniques can be used to shed a new light on the dissipative dynamics of spinning astrophysical objects. After introducing the basic formalism, I will discuss two different applications. The first one is a modern description of superradiance — a phenomenon by which a spinning object can loose angular momentum by amplifying the intensity of scattered radiation, or by producing particles in a bound state. Along the way, I will also provide a simple derivation of vacuum friction — a “quantum torque” that acts on spinning objects in empty space. The second application I will discuss (if time will allow it) is to tides and the role they play in the dynamics of moons, planets and other “Newtonian” objects. I will argue in particular that the time scales over which orbit circularization and tidal locking take place satisfy a hierarchy which follows exclusively from symmetry and is thus a model independent prediction of the effective theory.

Time: 2pm

Location: 2N36

Title: TBA

Time: 2pm

Location: 2N36

Title: Relative entropy of excited states in conformal field theories

Abstract:We study the relative entropy between the reduced density matrices obtained from globally excited states in conformal field theories of arbitrary dimensions. We find a general formula in the small subsystem size limit. When one of the states is the vacuum of the CFT, our result matches with the holographic entanglement entropy computations in the corresponding bulk geometries, including AdS black branes. We also discuss the first asymmetric part of the relative entropy and comment on some implications of the results on the distinguishability of black hole microstates in AdS/CFT.

Time: 2pm

Location: 2N36

**Title**: Recent developments in 3-D dualities

**Abstract**: This summer has seen a flurry of activity in particle-vortex duality and, more generally, in non-supersymmetric dualities in three spacetime dimensions. Much of this work has been directly related to the properties of so-called topological quantum matter and gapped phases of matter. In this talk, I will give a more-or-less pedagogical introduction to these ideas, beginning with the sine-Gordon/massive Thirring correspondence and building toward our current understanding of the 3-dimensional web of dualities.

Time: 2pm

Location: 2N36

Title: No-go results and promising directions in the space of causal diamonds

Abstract: The space of causal diamonds recently brought to attention by de Boer et al. and Czech et al. provides an organizing principle for the dependence of entanglement entropy in conformal field theories on the spatial subregion considered. I will show that the inclusion relation of causal diamonds does not give rise to a consistent notion of a causal structure and thus does not provide an alternate metric on this space. I will also show that the entanglement entropy of ball shaped regions is not enough to reconstruct the areas of higher dimensional bulk surfaces in a static geometry. Instead, I will provide a new direction for the reconstruction of the areas of bulk surfaces from boundary data in holography, using the shape derivatives of the entanglement entropy of nearly ball shaped regions.

Time: 2pm

Location: 2N36

Title: New forms of quantum entanglement in discretely gauged theories

Time: 2pm

Location: 2N36

Title: Entanglement growth in quantum quenches

Abstract: A global quench is an interesting setting where we can study thermalization of subsystems in a pure state. We investigate the spread of entanglement following a global quench in free field theory, holography, spin chains, and toy models. We find that the results in free scalar field theory are exactly reproduced by the model of free streaming quasiparticles, but strongly interacting chaotic systems spread entanglement more effectively. Based on recent insight into many-body quantum chaos, we propose two inequalities on the entropy, and suggest that the true evolution of the entropy is well approximated by saturating the combined bounds. A model based on the chaotic growth of operators saturates the combined bounds, and is a promising candidate to replace the quasiparticle model for chaotic systems.

Time: 2pm

Location: 2N36

Title: AdS_2 holography and non-extremal black holes

Abstract: I will present aspects of AdS_2 holography for a specific Einstein-Maxwell-Dilaton model that is obtained by Kaluza-Klein reduction from pure AdS_3 gravity with negative cosmological constant. In particular, I will derive the one-dimensional holographic dual for both running and constant dilaton solutions, and I will discuss the connection with the Sachdev-Ye-Kitaev model. Finally, I will explain how this dilaton gravity model provides a holographic description for four-dimensional asymptotically conformally AdS_2 x S^2 non-extremal black holes. The talk is based on the recent paper https://arxiv.org/abs/1608.07018.

Time: 2pm

Location: 2N36

Title: Entanglement, Holography and Causal Diamonds

Time: 2pm

Place: 2N36

Title: Tunneling in Quantum Field Theory and the Fate of the Universe

Abstract:

One of the most concrete implications of the discovery of the Higgs

boson is that, in the absence of physics beyond the standard model, the

long term fate of our universe can now be established through precision

calculations. Are we in a metastable minimum of the Higgs potential or

the true minimum? If we are in a metastable vacuum, what is its

lifetime? To answer these questions, we need to understand tunneling in

quantum field theory. As we delve into how tunneling works, we find many

unusual elements: complex quantities which should be real,

gauge-dependent quantities which should be physical, an hbar expansion

which differs from the ordinary loop expansion, and ultraviolet degrees

of freedom that don't decouple. This talk will discuss some of these

elements and present some new perspectives on quantum tunneling.

Time: 2pm

Place: 2N36

Title: "Bad Compactifications"

Abstract:

The parameter space of string compactifications contains a locus of

"bad" theories. These theories are physically the most interesting in

many ways. We analyze the bad locus of theories at various levels ---

where it is, it's multiplicity, and finally, we "categorify" it.

This is all done in the context of abelian gauged linear sigma models.