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Effective non-Hermitian evolution of a superconducting qubit: harnessing the topology of a Reimann surface for quantum control

Kater Murch (Washington University, St. Louis)


Horaire/Time : le mardi 18 janvier 2022 à 14:00


Lieu/Place : Visio-conférence Zoom hybride depuis Salle Rémy Lemaire K223, Institut Néel

Zoom link : https://univ-grenoble-alpes-fr.zoom.us/j/91808901596?pwd=UWZ2cml2N1VBOEZBenk0d3RJek9rdz09

Resumé/Abstract: A system described by a non-Hermitian Hamiltonian will, in general, have complex energies and non-orthogonal eigenstates. The degeneracies of such a system are known as exceptional points. Near these degeneracies, the complex energies are described by Riemann manifolds whose topology enables new methods of control over the system. Using a superconducting circuit QED platform we employ dynamical control over an effective non-Hermitian Hamiltonian to utilize the topology of its complex energy surfaces to control quantum state vectors. If a quantum system is initialized in one eigenstate, and the Hamiltonian parameters are varied slowly such as to encircle an EP, returning to the initial parameters, the topology of the Riemann manifold predicts that adiabatic evolution will switch the state to a different eigenstate. I will describe experiments where we observe this quantum state transport and use a quantum phase reference to measure the chiral geometric phases accumulated after this dynamical control.