This page is a work in progress
Introduction:
As explained in earlier posts, I worked with Rydberg states of atoms where the electron is excited to a very large orbital. This type of orbital is interesting because it is typically long-lived, posesses a large dipole moment and a large polarisability (from which stems giant rydberg-rydberg interactions). But Rydberg states can in principle be found in any quantum system supporting orbitals. In particular, the orbitals of exciton in a semiconducor (electron-hole bound state) are not necessarily the ground state: some crystals show giant Rydberg states of excions.
How are these exotic Rydbergs similar to their atomic cousins? Can we use their large nonlinearity in a similar fashion to what is done with atoms? Can we benefit from the larger energy scales of condensed matter? These questions are at the center of my new experimental project, which I am starting at the Laboratoire de Physique de l’Ecole Normale Supérieure (LPENS) as a Junior Researcher.
Description:
In Copper Oxide, Rydberg states up to the principal quantum number n=25 were observed and studied. However, few experiments aimed at coupling these states with light so as to create Rydberg polarions, a method that triggered a boom in cold atom research. One of the main hindrance is a large phonon-assisted scattering background due to the crystaline matrix hosting the Rydberg excitons. A promissing approach to sidestep this issue is a two-photon excitation, actually quite similar to the EIT approach I worked with in cold atoms. Using my dual expertise on exciton-polaritons + atomic Rydberg states and the savoir-faire of the Nano-THz team at LPENS, I aim to implement a new visible + THz excitation scheme that will push our knowlegde and mastery of Rydberg exciton physics.
Long-term goals:
When many particles interact, the emerging collective behavior is often counter-intuitive and too complex to compute. To probe collective behavior, all approaches so far use interacting matter despite the extreme challenge of measuring the full many-body state of massive particles. Light is comparatively easy to measure, but does not form many-body states by lack of significant photon-photon interaction.
My project will pioneer a new semiconductor-based concept for strong photon-photon interactions, designed for the full characterization of complex many-body states. Its core innovation is to transfer giant interactions from Rydberg excitons to optical photons. With this new line of attack, I will create a novel platform to explore complex problems of correlated condensed matter with light. My approach presents unique advantages:
- Mimicking complex material systems with light, it unlocks the direct detection of elusive many-body information like spatial phase correlations;
- Bringing delicate cold atoms techniques to the much higher energy scales of condensed matter, it allows large-scale all-optical control of many-photon states;
- As a chip-sized solid-state platform, it can be micro-structured to design increasingly complex experiments with an arbitrary geometry.
The end goal is therefore a novel photonic quantum simulator tailored to shed light on universal many-body properties, such as those underlying quantum phase transitions. Moreover, dissipation can be engineered, which enables to test the competition between dissipation and interactions and explore dissipation-driven quantum phase transitions.