Wochenübersicht – nächste Woche

Neutron stars: from macroscopic collisions to microphysics I will argue that if black holes represent one the most fascinating implications of Einstein's theory of gravity, neutron stars in binary system are arguably its richest laboratory, where gravity blends with astrophysics and particle physics. I will discuss the rapid recent progress made in modelling these systems and show how the gravitational signal can provide tight constraints on the equation of state for matter at nuclear densities, as well as on one of the most important consequences of general relativity for compact stars: the existence of a maximum mass. Finally, I will discuss how the merger may lead to a phase transition from hadronic to quark matter. Such a process would lead to a signature in the post-merger gravitational-wave signal and open an observational window on the production of quark matter in the present Universe.

Cosmic inflation is an important paradigm of the early Universe which is so far developed in two equivalent ways, either by geometrical modification of Einstein's general relativity (GR) or by introducing new forms of matter beyond the standard model of particle physics. Starobinsky's R+R^2 inflation based on a geometric modification of GR is one of the most observationally favorable models of cosmic inflation based on a geometric modification of GR. In this talk, I will discuss in detail the fundamental motivations for Starobinsky inflation and present how certain logical steps in the view of its UV completion lead to the emergence of a gravity theory that is non-local in nature. Then I will establish how one can perform studies of the early Universe in the context of non-local gravity and what are the observational consequences in the scope of future CMB and gravitational waves. I will discuss in detail how non-local R^2-like inflation can be observationally distinguishable from the local effective field theories of inflation. Finally, I will comment on prospects of non-local gravity as a promising candidate for quantum gravity.

Atoms in their highly excited electronic states, referred to as Rydberg atoms, have extraordinary nonlinear optical properties. Such atoms are highly polarizable and interact with each other via the dipole-dipole or the van-der-Waals interactions. Owing to these interactions, Rydberg atoms in optical traps possess the condensed matter-like collective behavior. They serve as a viable platform to study quantum many-body physics. Spin degrees of freedom of trapped Rydberg atoms bring rich new physics including quantum magnetism, quantum phases, and entanglement - a crucial resource in many quantum information and quantum communication tasks. In this talk, I will present a study of alkali rubidium atoms trapped in an optical lattice and controllably excited to the Rydberg states by linearly chirped laser pulses [1]. I will introduce a quantum control methodology to create entangled states of two typical classes, the W and the Greenberger-Horne-Zeilinger (GHZ) [2]. I will show that the entangled states of Rydberg atoms can be used to create the multiphoton entangled radiation states in a cavity and in free space [3]. The methodology exploits chirped-pulse adiabatic passage and provides a key step toward the resolution of a general problem of creating entanglement in high-dimensional quantum entities.

The distribution of nanoparticles (NPs) within the polymer brush is a crucial element that determines their applicability, such as in nanosensors. The brush properties, such as grafting density, thickness, etc., can be used to control the structure formation of NPs. Here, we are interested in studying the assembly formation of NPs, in particular, by tuning the brush properties.

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