Exploring the many-body regime of light-matter interaction
Nicolas Roch
(Institut Néel, Grenoble)
| When |
May 04, 2018
from 10:45 to 12:00 |
|---|---|
| Where | salle des Commissions |
| Attendees |
Nicolas Roch |
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Understanding the way light and matter interact remains a central topic in modern physics despite decades of intensive research. Since the end of the last century, the focus has been to isolate individual quantum systems (the “matter”) and to couple them to single electromagnetic degrees of freedom (the “light”), giving birth to the celebrated field of cavity quantum electrodynamics. Owing to the naturally large light-matter interaction in superconducting quantum circuit, it is now realistic to think about experiments where the actual dynamics of environments containing many degrees of freedom becomes relevant. It suggests that many-body quantum optics is within reach. Apart from quantum optics, the control and tunability of circuits should allow us to bring new perspectives to phenomena usually observed in condensed matter physics or open quantum systems. Indeed, if the different theoretical predictions are to be validated, it is crucial to design experiments where the different degrees of freedom can be perfectly modeled.
In this talk I will present a recent experiment [1]. The system under study consists in a single superconducting quantum bit ultra-strongly coupled to a large environment made of 4700 SQUIDs. This meta-material sustains many electro-magnetic modes. By performing microwave spectroscopy of this many-body system, we could understand in details how the qubit and its environment interact and hybridize. Thanks to a precise modeling of the system, these data can be explained by a theory without free parameters despite the fact that all the many-body ingredients are at play: non-perturbative coupling, many degrees of freedom and strong non-linearity. Finally I will also present our on-going efforts to observe many-body renormalisation in such systems and its links with dissipative quantum phase transitions.
[1] J. Puertas-Martinez et al., arXiv:1802.00633