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Calendar of Physics Talks Vienna
| Cosmological Chaos, Complexity, and the OTOC |
| Speaker: | Bret Underwood (Pacific Lutheran University) |
| Abstract: | Several approaches to investigating quantum chaos have recently emerged, including quantum circuit complexity and the out-of-time-order correlator (OTOC). In this talk, I will briefly introduce these ideas and apply them to squeezed states, including the squeezed state description of cosmological perturbations on a variety of cosmological backgrounds, such as de Sitter accelerated expansion. Some intriguing results from this investigation include a bound on the growth rate of cosmological complexity reminiscent of a similar bound on the quantum Lyapunov exponent, and the observation that among all cosmological backgrounds, only de Sitter space leads to the exponential growth of the OTOC that is a signature of quantum chaos. |
| Date: | Thu, 29.10.2020 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | https://tuwien.zoom.us/j/95482849369?pwd=SkU2WU5hMVJBQWsyVlFXRlRvQlIvdz09 |
| Contact: | Laura Donnay, Niccolo Cribiori |
| The Gregory—Laflamme Instability of the Schwarzschild Black String Exterior |
| Speaker: | S.C. Collingbourne (Cambridge) |
| Abstract: | In this talk I will discuss my work on a direct rigorous mathematical proof of the Gregory--Laflamme instability for the five-dimensional Schwarzschild black string(https://arxiv.org/abs/2007.08441).This is a mode instability at the level of the linearised vacuum Einstein equation.Under a choice of ansatz for the perturbation and a gauge choice,the linearised vacuum Einstein equation reduces to an ODE problem for a single function.In this work a suitable rescaling and change of variables is applied which casts the ODE into a Schrödinger eigenvalue equation to which an energy functional is assigned.It is then shown by direct variational methods that the lowest eigenfunction gives rise to an exponentially growing mode solution which has admissible behaviour at the future event horizon and spacelike infinity.After the addition of a pure gauge solution,this gives rise to a . . . |
| Date: | Thu, 29.10.2020 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | online - https://zoom.us/j/4200372900?pwd=c01vb0FNRU94V0JVdWlnaDE0eUwwQT09 |
| Contact: | Piotr Chrusciel, David Fajman |
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