Channeling Quantum Interactions: experiments in waveguide QED with superconducting quantum circuits

25 Jan
Applied Physics Colloquia
Oskar Painter, CalTech
Friday, January 25, 2019 - 4:00pm to 5:00pm
Maxwell Dworkin G115

The complexity and emergent behavior of a many-body quantum system is intimately related to the connectivity of its constituent quantum elements.  In the case of Josephson junction qubits and superconducting quantum circuits, connectivity between qubits can be realized using myriad of techniques.  Near-field interactions, through capacitive or inductive components, can be used to realize local connections.  Microwave resonators with closed electromagnetic boundaries, like that in a 3-dimensional superconducting box cavity, can provide all-to-all coupling between qubits, albeit typically in a manner that results in a system with effectively 0 spatial dimensions.  Nontrivial long-range interactions, however, can be mediated in a superconducting microwave circuit using waveguides which channel microwave radiation.  Waveguide quantum electrodynamics (QED), which explores the interactions of quantum emitters with the continuum of electromagnetic modes of a one-dimensional radiation channel, is thus a natural setting in which to consider the emergent physics that may be possible using superconducting quantum circuits.  In this talk I will describe two waveguide QED experiments that we have recently performed, one involving strong dispersion in engineered metamaterial waveguides and the other probing coherent dynamics arising from photon-mediated interactions between distant qubits connected along a common waveguide.  From these two experiments, I will also chart a course for future experiments that would allow us to study many-body interactions and open quantum system dynamics in the non-Markovian limit.      

Speaker Bio: 

Oskar Painter received his Bachelor of Applied Science degree in Electrical Engineering from the University of British Columbia in 1994, his Master of Science degree from the California Institute of Technology in 1995, and his Ph.D. in Electrical Engineering from the California Institute of Technology in 2001.  He joined the faculty at the California Institute of Technology in 2002, where he is now the John G. Braun Professor of Applied Physics, Professor of Physics, and the co-Director of the Kavli Nanoscience Institute.  Prof. Painter's current research interests are in studying the quantum properties of mechanical systems and in the development of hybrid superconducting quantum circuits for quantum information processing applications.  He has received several awards and recognitions including most recently an Alexander von Humboldt Professorship – an International Award for Research in Germany.

Marko Loncar
Kathy Masse