Seminar Schedule

Precision spectroscopy is a driving force for the development of our physical understanding. However, only few atomic and molecular systems of interest have been accessible for precision spectroscopy in the past, since they miss a suitable transition for laser cooling and internal state detection. This restriction can be overcome in trapped ions through quantum logic spectroscopy [1]. Coherent laser manipulation originally developed in the context of quantum information processing with trapped ions allows us to combine the special spectroscopic properties of one ion species (spectroscopy ion) with the excellent control over another species (logic or cooling ion). The logic ion provides sympathetic cooling and is used to control and read out the internal state of the spectroscopy ion. In my talk I will provide an overview of different implementations and applications of quantum logic spectroscopy to investigate previously inaccessible species such as molecular ions [2] and highly charged ions [3]. Spectroscopy of these species may reveal physics beyond the standard model, such as new force carriers or scalar fields that are dark matter candidates and could induce a variation of fundamental constants, or appear as nonlinearities in isotope shift spectroscopy.

We will discuss the recent advances involving programmable, coherent manipulation of quantum many-body systems using atom arrays excited into Rydberg states. Specifically, we will describe our recent technical upgrades that now allow the control over 200 atoms in two-dimensional arrays. Recent progress involving the realization of exotic states of matter, exploration of their non-equilibrium dynamics as well as realization and testing quantum optimization algorithms using such systems will be discussed.

Quantum optical systems with cold atoms and ions provides one of the best ways to build controllable quantum many-body systems as quantum computers and quantum simulators. Here we report on recent developments in building, and in particular programming quantum simulators based on trapped ions as intermediate scale quantum devices. Our discussion will focus on hybrid classical-quantum scenarios: here the quantum part is the generation of highly entangled states on the quantum device in quench dynamics, which is combined with a classical post processing of measurement data, possibly run in a feedback loop with the quantum device. Examples highlighting these developments include the implementation of self-verifying variational quantum simulations, illustrated here by computing the ground state and quantum phase transition of a Schwinger Model as 1D QED. In addition, we develop and demonstrate a ‘randomized measurement toolbox’, allowing to access in experiments quantities like Renyi entanglement entropies and — as ongoing research — measure the entanglement spectrum, i.e. ‘seeing the Schmidt decomposition live’ in quench dynamics from an initial product state towards thermodynamic equilibrium.