DualMysteryChannel

Date: June 4

Time: 17:30 IST (UTC + 5:30)

Speaker: Tanay Kibe (IIT Madras)

Title: NAdS2 Lattices are Information Mirrors

Abstract: Looking at black holes as quantum circuits, it has been argued that black holes act as quantum information mirrors. If Alice throws some quantum information inside the black hole after the Page time, it eventually leaks out after the Hayden-Preskill time. Bob can obtain this information by performing a decoding operation on the Hawking radiation. The information leaks out of the black hole in a “last in-first out” manner. The qubits thrown inside just after the Page time leak out before the qubits that went in before the Page time. Taking inspiration from the fragmentation of the near horizon geometry of a near-extremal black hole, we have constructed a model that can reproduce some of the information processing properties of a black hole. Our model is a lattice of two dimensional nearly anti-de Sitter spacetimes. In this talk I will show that our model indeed behaves like an information mirror and thus mimics the Hayden-Preskill protocol.

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NAdS2Lattice.pdf

Date: June 12

Time: 17:30 IST (UTC + 5:30)

Speaker: Souvik Banerjee (Univ. of Würzburg)

Title: Riding a dark bubble

Abstract: In this talk I will discuss the possibility to induce dark energy on a generalized braneworld geometry realized on the wall of an expanding bubble. I will show that the construction would eventually convert a problem of instability into a virtue that would help us to set up a reliable cosmological model of the universe.

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Dark-bubble-chennai.pdf

Date: June 18

Time: 17:30 IST (UTC + 5:30)

Speaker: Blaise Goutéraux (CPHT, E'cole Polytechnique, Palaiseau)

Title: Normal densities in cool quantum critical superfluids

Abstract: It is common belief that at zero temperature, a phase that spontaneously breaks a U(1) symmetry becomes entirely superfluid, ie the normal density vanishes. This is indeed the case in a variety of systems, such as weakly-coupled Helium, BCS superconductors and relativistic superfluids described by a quantum effective action originally written by Son. Here, I will show that this expectation fails in certain classes of holographic superfluids, such as those with a Lifshitz-invariant critical ground state with Lifshitz exponent z>d+2 (d is the number of spatial dimensions), thus clarifying previous results in earlier literature. Time permitting, I will conclude by commenting on the relevance of these results for recent measurements in overdoped high Tc superconductors revealing an anomalously low superfluid density at odds with BCS theory expectations.

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DualMysteryChannel-2020-GOUTERAUX.pdf

Date: June 25

Time: 17:30 IST (UTC + 5:30)

Speaker: Alexander Soloviev (Stony Brook Univ)

Title: Transport and hydrodynamic fluctuations in the chiral limit

Abstract: I will discuss the evolution of hydrodynamic fluctuations for QCD matter below T_c in the chiral limit. The theoretical description is ordinary hydrodynamics at long distances and superfluid-like at short distances. The latter is represented by pions (the Goldstone modes), reflecting the broken SU(2)_L x SU(2)_R symmetry. The superfluid degrees of freedom contribute to the transport coefficients of the ordinary theory at long distances. This determines the leading dependence of some transport parameters of QCD on the pion mass. I will make some comments on the predictions of this computation near the O(4) critical point.

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mystery_talk.pdf