2 JUN 2020
13:30 - 16:30

Venue:

Opposite the ARAJ, Artesh Highway, Tehran, Iran
School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM),



* To join the mailing list: Send an empty email to: scs at ipm dot ir on the subject of: #join seminar-list

28 MAY 2020
11:00 - 12:00

Abstract: In this talk, I show how infinitesimal superrotations can be expressed, in harmonic gauge, in terms of metric components evaluated at the boundaries of null infinity that are subleading in a large radius expansion. Then I recast the spin memory observable in terms of these boundary values.

28 MAY 2020
11:00 - 12:00

Abstract: Quantum corrections to the entanglement entropy of matter fields interacting with dynamical gravity have proven to be very important in the study of the black hole information problem. We consider a one-particle excited state of a massive scalar field infalling in a pure AdS3 geometry and compute these corrections for bulk subregions anchored on the AdS boundary. In the dual CFT2, the state is given by the insertion of a local primary operator and its evolution thereafter. We calculate the area and bulk entanglement entropy corrections at order O(N^0), both in AdS and its CFT dual. The two calculations match, thus providing a non-trivial check of the FLM formula in a dynamical setting. Further, we observe that the bulk entanglement entropy follows a Page curve. We explain the precise sense in which our setup can be interpreted as a simple model of black hole evaporation and comment on the implications for the information problem.


Larak Seminar Room

28 MAY 2020
-

Quantum corrections to the entanglement entropy of matter fields interacting with dynamical gravity have proven to be very important in the study of the black hole information problem. We consider a one-particle excited state of a massive scalar field infalling in a pure AdS3 geometry and compute these corrections for bulk subregions anchored on the AdS boundary. In the dual CFT2, the state is given by the insertion of a local primary operator and its evolution thereafter. We calculate the area and bulk entanglement entropy corrections at order O(N^0), both in AdS and its CFT dual. The two calculations match, thus providing a non-trivial check of the FLM formula in a dynamical setting. Further, we observe that the bulk entanglement entropy follows a Page curve. We explain the precise sense in which our setup can be interpreted as a simple model of black hole evaporation and comment on the implications for the information problem.

27 MAY 2020
13:30 - 15:00

QPOs are seen as peak features in the X-ray power spectral density of stellar mass black holes and neutron stars, of which frequencies can be measured with high precision. These QPO frequencies are believed to be related to fundamental frequencies of test particles, which are mainly determined by the background metric. We consider a non-Kerr metric. The fundamental frequencies in this metric are sensitive to some of the metric parameters but insensitive to other parameters, which means, the differences in fundamental frequencies in this metric and those in the Kerr ones can be significant for small changes of some but not all parameters around the Kerr value. By comparing with the QPO observations of GRO J1655-40, we find that only one parameter of the metric can be strongly constrained, but other parameters cannot. We also use nested algorithm to investigate whether better constraints on the metric parameters can be obtained from QPO observations of multiple objects by simulations. We find that four parameters can be strongly constrained while other parameters cannot . Our results suggest that QPOs may be important tools for testing the Kerr metric.

27 MAY 2020
14:00 - 15:00

https://meet.jit.si/WeeklySeminar-SchoolofPhysics

21 MAY 2020
11:00 - 12:00

21 MAY 2020
11:00 - 12:00

Abstract: We will analyze the information paradox in two-dimensional models of gravity. In this setting, we will show that new saddles in the gravitational path integral imply a unitary Page curve for the entropy of Hawking radiation. These saddles arise in the replica method as wormholes connecting different copies of the black hole. We will focus on these saddles in anti-de Sitter spacetime, but if time permits we will also discuss flat and de Sitter spacetimes.


Larak Seminar Room

21 MAY 2020
-

We will analyze the information paradox in two-dimensional models of gravity. In this setting, we will show that new saddles in the gravitational path integral imply a unitary Page curve for the entropy of Hawking radiation. These saddles arise in the replica method as wormholes connecting different copies of the black hole. We will focus on these saddles in anti-de Sitter spacetime, but if time permits we will also discuss flat and de Sitter spacetimes.

20 MAY 2020
14:00 - 15:00

Low-loss two-dimensional plasmon modes in antimonene

Abstract:

The effects of spin-orbit (SOC) and electron-phonon coupling on the collective excitation of doped monolayer Sb2 are investigated using density functional and many-body perturbation theories. The spin-orbit coupling is exclusively important for the monolayer Sb2 and it leads to the modification of the electronic band structure. In particular, plasmon modes of monolayer Sb2 are quite sensitive to the SOC and are characterized by very low damping rates, owing to small electron-phonon scatterings. Our results show how plasmons in antimonene are significantly less damped compared to monolayer graphene when plasmon energies are larger than 0.2 eV due to smaller plasmon-phonon coupling in the former material.

20 MAY 2020
13:30 - 15:00

The theory of stochastic processes has developed very rapidly and has found application in a large number of fields; for example, the study of fluctuations and noise in the physical system, in the information theory of communication and control, in biology, in astronomy, and so on. In this talk, I will give a brief review of the mathematical tools required to describe the stochastic processes. I will discuss how the stochastic theory is used to study the quantum fluctuations during inflation. The transition from these quantum fluctuations to classical but stochastic density perturbations gives rise to the stochastic inflation formalism. Finally, I revisit the stochastic effects in the model of anisotropic inflation containing a U(1) gauge field

20 MAY 2020
14:00 - 15:00

Organized by: School of Nano Science

Link of the meeting room:https://meet.jit.si/Nano_Science_WeeklyWebinar