CQD Special Seminars

20. Mai 2026 16:30 Uhr

Physikalisches Institut, INF 226, K 1-3

Ultracold lithium-chromium mixtures: From mass-asymmetric fermionic matter to paramagnetic molecules

Dr. Matteo Zaccanti, INO-CNR & LENS, Physics Department, University of Florence

Quantum mixtures of different atomic species represent compelling frameworks for a variety of fundamental studies and quantum-technological applications, ranging from the exploration of exotic few- and many-body phenomena to the realization of novel molecular species in the ultracold regime.

Here, I will first provide a general overview of the activities of our lab, primarily based on a novel Fermi-Fermi mixture of ⁶Li alkali and ⁵³Cr transition-metal atoms, and currently focusing onto two main research topics: realization of quantum gases of LiCr molecules, and investigation of strongly interacting fermionic matter in presence of a large mass asymmetry.

I will then discuss in more detail a recent study of transport dynamics of a small sample of ultracold lithium atoms – acting as light impurity particles – released into a large, ideal gas of chromium – that plays the role of a bath of heavy, point-like scatterers. Under strong interspecies interactions, by lowering the temperature we unveil a crossover from normal diffusion to subdiffusion. Simultaneously, a localized fraction emerges in the lithium gas, displaying no discernible dynamics over hundreds of collision events. Our findings, incompatible with a conventional Fermi-liquid picture, are instead captured by a model of a matter wave propagating through a (quasi-)static disordered landscape of point-like scatterers. These results point to a key, enhanced role of quantum interference in heavy-light atomic mixtures, which emerge as versatile platforms for exploring disorder-free localization phenomena solely driven by a large mass difference.

 PreTalk: Tobias Hammel, Physikalisches Institut, Uni Heidelberg: "Now you see them, now you don't: Hiding atoms with light"

1. Juni 2026 13:30 Uhr

Physikalisches Institut, INF 226, K 1-3

Probing and controlling dipolar many-body dynamics in disordered spin ensembles in diamond

Jenny Jiang, University of Cambridge

The dynamics of interacting, disordered quantum systems is a central topic in many-body physics. Dense ensembles of nitrogen-vacancy centres (NVs) in diamond provide a unique platform to realise a strongly interacting, intrinsically disordered spin systems with long-range dipolar interactions at room temperature. This enables access to rich many-body physics including thermalisation, non-equilibrium dynamics, and dimensional crossovers.

In this talk, I will first introduce the NV as a controllable spin platform and discuss how interactions within an ensemble give rise to complex many-body behaviour. I will then explain how we can probe the spin environment and selectively control interactions with Hamiltonian engineering techniques. A central challenge in using these systems as quantum simulators is the lack of precise knowledge of the interaction within a sample. I will present my work on using tailored pulse sequences as spectroscopic tools to characterise the spin bath and extract key parameters governing the system dynamics. This provides a route towards quantitative control of disordered spin ensembles and the exploration of emergent many-body physics in solid-state quantum simulators.