Heidelberg 2015 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 19: Quantum Gases: Fermions III

Q 19.5: Talk

Tuesday, March 24, 2015, 12:00–12:15, K/HS2

Emergence of orthogonality in the Fermi impurity problem — •Simon Murmann, Andrea Bergschneider, Vincent M. Klinkhamer, Gerhard Zürn, and Selim Jochim — Physikalisches Institut der Universität Heidelberg, Heidelberg, Deutschland

In quasi one dimensional systems, the ground-state wavefunction of an impurity particle interacting with a Fermi sea is orthogonal to the wavefunction of the non-interacting system. In this case the squared overlap between the interacting and the non-interacting systems, which is defined as the quasiparticle residue, is zero.

Here, we report on measurements of the residue of a single fermionic impurity particle interacting with an increasing number of majority particles. To probe the system, we flip the spin of the impurity particle by driving a radio frequency (RF) transition. In a previous experiment we used RF spectroscopy to measure the interaction energy in this system while increasing the number of majority particles one atom at a time and thereby observed the crossover from few to many-body physics [1]. Now, we measure how the wavefunction overlap between initial and final states changes both as a function of interaction strength and the number of majority particles. Our goal is to extend these measurements into the crossover region between few and many-body physics by increasing the number of majority particles and thereby observe the emergence of the orthogonality catastrophe.

[1] Wenz et al. Science 342, 457 (2013)