November 2024
Abstracts of the Quantum Center Lunch Seminar
Date: Thursday, November 7, 2024
Place: ETH Zurich, Hönggerberg, HPF G 6
Time: 12:00 - 13:30
Quantum circuits based on topological pumping in optical lattices
Konrad Viebahn - Quantum Optics (Esslinger group), ETH Zurich
Optical lattices are a unique tool to prepare and position large numbers of atoms in well-defined internal and motional states. Despite their excellent coherence properties, progress in employing ultracold atoms in optical lattices as a quantum information platform has been limited. An open challenge in this context is the coherent of transport atoms through the lattice.
In this talk, I will introduce bidirectional topological Thouless pumping as a toolbox to transport, separate, interweave, and recombine atomic quantum states in an optical lattice. Starting from entangled pairs of potassium-40 atoms, we are able to spatially coherently delocalise fermionic spin singlets by as much as 19 lattice sites1. During transport, we control the collisions between neighbouring spin singlets via programmable SWAP and sqrt(swap) gate operations. Our results guide the way towards quantum information processing in optical lattices.
1 Zhu et al. “Quantum circuits based on topological pumping in optical lattices” external page arXiv:2409.02984
Probing New Physics with Calcium Isotope Shift Measurements
Luca Huber - Trapped Ion Quantum Information (Home group), ETH Zurich
Precision metrology has emerged as a powerful technique for probing physics beyond the Standard Model of particle physics. In this talk, I present our work on measuring the isotope-dependent frequency shift of a quadrupole transition in all even and stable calcium isotopes. We perform correlation spectroscopy on two ions of different isotopes, co-trapped simultaneously in the same Paul trap. By leveraging a decoherence-free subspace within these two ions, our experiment is robust against magnetic field fluctuations and laser phase noise, enabling measurements beyond the coherence time of our system.
Isotope shifts are sensitive to a hypothetical force-carrying boson mediating interactions between neutrons and electrons and hence allow us to probe for New Physics. With a statistical uncertainty below 30 mHz, we significantly tighten constraints on the coupling of the hypothesized boson, surpassing limits set by previous experiments. Our use of single-ion control, originally developed for trapped-ion quantum computing, underscores the deep connection between quantum information processing and quantum metrology.