Studies on the ultra-strong coupling limit of light-matter interactions
Abstract
Recently, a new light-matter regime in cavity quantum electrodynamics (QED), named ultrastrong coupling (USC) regime, where the coupling rate of the interaction between an atomic transition and one cavity photon becomes comparable to the atomic transition frequency or the resonance frequency of the cavity mode has been observed in several solid slate systems. The interest in the USC regime is rapidly growing, fostered by the vast phenomenology which has been predicted to be observable in such a regime. The weak and strong coupling regimes of cavity-QED gave rise to several applications in the fields of high-precision measurements and quantum information science. The USC regime, which is providing new insights into the quantum aspects of the interaction between light and mailer, enables new physical processes that can lead to new applications. This proposal has three separate Task options. Each Task option can be funded separately: 1) EXPERIMENTS ON VACUUM-INDUCED SYMMETRY BREAKING AND ON ANOMALOUS NONLINEAR OPTICS EFFECTS. Collaborations with two experimental groups working on circuit-QED in the USC regime have already started and will be strengthened with the goal of realizing experimental demonstrations of intriguing USC effects, predicted theoretically. We will provide theoretical support for the samples design, as well as for the interpretation and fit of the experimental data. In particular, in collaboration with Prof. J.Q. You, we will explore the effects of a dressed vacuum on a probe artificial atom. 2) EXTENSION OF ANOMALOUS NONLINEAR OPTICAL EFFECTS TO MANY ATOMS AND TO MANY MODES. This will open the possibility to observe these effects on a large number of physical systems, as cold atoms, organic molecules, spin systems and superconducting quantum circuits with many artificial atoms. Moreover, exciting pairs of atoms in a large ensemble by just sending weak optical coherent pulses is expected to produce robust many-particle entanglement and efficient spin squeezing. Spin squeezing is very important for improving the precision of measurements. Extension of the theoretical analysis to include many modes and waveguide-QED. The inclusion of many modes is important in order to fully understand propagation phenomena inside resonators and to investigate the impact of higher energy modes on the new physical processes enabled by this interaction regimes. Multimode approaches are also important for the description of waveguide-QED systems in the USC regime. These results will extend the range of applications of this regime. 3) USC OPTOMECHANICS. In our recent paper published on Phys. Rev. X. the first ab-initio study of the dynamical Casimir effect in an optomechanical system has been presented. The aim of this project is to investigate optomechanical systems in the USC regime in order to explore new related effects as, for example, the transfer of mechanical excitations between two oscillators without exciting the medium filling the gap. METHODS: When considering Bosonic systems, generalized Hopfield transformations will be used, while systems with a single or a few artificial atoms will be treated with matrix product states methods. In quantum optics, the standard approach to treat open quantum systems fails in the USC limit. Hence a general master equation approach and a generalized Montecarlo-wavefunction method for arbitrary hybrid quantum systems with arbitrary coupling strength, recently developed by the Pl and his collaborators will be adopted.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 11, 2019
- Source ID
- W911NF1910065
Entities
People
- Salvatore Savasta
Organizations
- Army Contracting Command
- United States Army
- University of Messina