PhD (M/F): Cavity mediated transport

Job Description

Thesis Subject

Cavity polaritons are hybrid light-matter states issued from the strong coupling between a cavity mode and a material excitation. The optical properties of the material are profoundly modified by the emergence of such states. Indeed, in the strong coupling regime, the cavity polaritons are the bright modes of the system, while the bare material excitation becomes dark. In the last thirty years, the possibility of creating and manipulating cavity polariton states had a major impact on quantum optics and quantum electrodynamics, with important breakthroughs such as the implementation of Schrödinger cats or the observation of Bose-Einstein condensates.
Recently, several experiments demonstrated that the emergence of hybrid light-matter states can have an impact on other physical properties, like charge or energy transport, chemical reactions, phase transitions, thermodynamics. With these demonstrations, the importance of strong light-matter coupling spread well beyond electrodynamics by entering in other fields of physics and chemistry.
This PhD project is an experimental and theoretical study on the impact of strong light-matter coupling on charge transport. Two different material excitations will be considered: (a) a plasmon confined in a highly doped semiconductor layer; (b) a vibrational mode of water confined in a porous material, fabricated in collaboration with Marco Faustini at LCMCP (Sorbonne Université). We will use as photonic platform a metamaterial based on a periodic array of metal – dielectric – metal resonators. This photonic platform is very well suited for the confinement of mid-infrared radiation in highly subwavelength regions thanks to the presence of metals, which also act as electrical contacts.
We have already demonstrated strong light-matter coupling regime in both material platforms by performing reflectivity experiments. In both cases, the strength of the coupling is determined by the extremely high density of dipolar oscillators, giving rise to a collective response. In this PhD work, we will investigate charge transport in these systems, where the existence of polaritons is undiscussed.
In the case of confined plasmons, we will study vertical transport, and more precisely we will investigate the charge transport as a mean of energy transfer from a dc current to a polariton state, that can emit mid-infrared radiation. To this aim, we will design a semiconductor heterostructure engineered such that an electronic transition, that can be excited through tunnelling, is resonant with the polariton mode. The mechanisms for such electrical excitation of the polariton states will be theoretically investigated.
In the case of water in porous materials, we will investigate ionic transport. In this case, our metamaterial platform will allow the investigation of both parallel and vertical transport. The modification of ionic conductivity of water induced by the coupling with a cavity mode has already been experimentally demonstrated. However, the observation of this phenomenon in porous materials will be extremely appealing, as this platform is well suited for water electrocatalysis for H2 production.
The investigation in the two platforms and the comparison between them will help us in gaining insights into phenomena related to cavity mediated transport, whose theoretical description is still debated.

Your Work Environment

This PhD project will be conducted within the framework of the ANR project Exapor, and will benefit of all the exchanges between the different partners at LPENS, Sorbonne Université and Université Paris Cité.

Constraints and risks

Chemical risk associated with the preparation of samples.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

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