October 2024

Abstracts of the Quantum Center Lunch Seminar

Date: Thursday, October 3, 2024
Place: ETH Zurich, Hönggerberg, HPF G 6
Time: 12:00 - 13:30

Autonomous Quantum-Informed Free Energy Calculations of Ligand Binding

Thomas Weymuth - Theoretical Chemistry (Reiher group), ETH Zurich

The so-called binding free energy is a key quantity in many biological processes. Among other things, it determines how well a drug candidate binds to its target. However, an accurate calculation of binding free energies is very involved due to the quantum nature of molecules. Since quantum computers offer the possibility to store an exponential number of states with a linear number of qubits, they are potential game changers for reliable and accurate models for molecular interactions.
However, near-term quantum hardware will not permit applying such algorithms to large systems. Therefore, in collaboration with groups from MIT and the University of Copenhagen we have developed a computational pipeline combining classical and quantum algorithms. This allows us to employ powerful quantum algorithms for the most relevant parts of a system while applying classical methods to the rest. The basic concepts of this pipeline have been showcased at the General Meeting 2024 of the ETH Quantum Center; in this follow-up talk, we will present first results obtained.

Achieving strong magnon-photon coupling with YIG thin films

Davit Petrosyan - Magnetism and Interface Physics (Gambardella group), ETH Zurich

Magnetically ordered spin ensembles, such as ferro- and ferrimagnets, consist of a large number of spins that are strongly correlated through the exchange interaction and collectively reside in the ground state. The low-energy excitations of these systems are known as spin waves, and their quanta are called magnons. Recently, magnons have been probed using circuit quantum electrodynamics in hybrid magnon-polariton systems, which typically rely on bulk ferromagnetic materials for magnon excitation. The next step in quantum magnonics experiments is to probe magnon properties in nanoscale magnets.
Yttrium iron garnet (YIG) is the most studied material for magnon excitation as it displays the longest lifetimes of the magnonic modes. We present our recent work on the synthesis of lattice-tunable YIG compounds on garnet substrates for high-quality epitaxial growths. We demonstrate strong magnon-photon coupling with YIG thin films synthesized through our approach and a bulk 3D microwave cavity optimized to couple with magnetically ordered thin films. This opens new doors to realizing few-level quantum systems coupled to modes of other condensed matter systems.