Theory and numerical analysis of strongly coupled systems (M/F)

Job Description

Missions

We have an opening for a one year (initially) post-doctoral appointment at University Paris Saclay (France) and CNRS, with the Centre for Nanosciences and Nanotechnologies (C2N). You will integrate the Mid-IR /THz Quantum Devices Team, specialized in the development of novel optoelectronic devices
exploiting quantum electrodynamics effects at mid-infrared wavelengths.
Located south of Paris, University Paris Saclay extends across a vast local area and is ranked as France's top university.
The salary level can be negotiated depending on the candidate experience. The project is supported by an ERC Advanced Grant (project SMART-QDEV).

The goal of the project is to support with theory and modeling some of the team's activities, that focus on systems and devices operating in the strong-light matter coupling. The post-doctoral activity is theoretical, with particular attention to numerical analysis.

Activity

Optoelectronic devices, from light-emitting diodes and solar cells to lasers and detectors, are an integral part of our daily life and are expected to play an increasingly important role in the future. As the basic operating principles of optoelectronic devices are known, their improvement – while important – is often incremental. Finding radically new avenues to implement novel functionalities is a key challenge: cavity quantum electrodynamics promises new approaches to innovate such devices by exploiting the concept of strong (SCR) light-matter coupling regimes in microcavities [1]. In this regime, the coupling of photons to electronic/molecular excitations exceeds the decay processes, inducing the formation of new hybridized states known as polaritons.

The activity of the team is aligned with this approach. In particular, the research focuses on optoelectronic devices relying on so-called intersubband transitions between quantum-confined electronic states in semiconductor quantum wells (QWs). Such transitions are the building blocks of mid-infrared/THz quantum devices (quantum cascade lasers, infrared QW detector). Furthermore, their flexibility recently led to the first demonstration of the ultra-strong light-matter coupling regime in solid-state physics [2] [3]. These devices suit the exploration of new phenomena where cavity electrodynamics plays a fundamental role.

The perspective candidate will tackle three main problems.

First: electronic transport in the ultra-fast modulators developed in the host team. We have recently demonstrated ultra-fast MIR modulators with performances that are compatible with real world applications [4]. The specificity (and the beauty) of the concept is that it relies on a fundamental physics phenomenon: the strong-coupling regime between light and matter. However, a persistent leakage current still plagues their performance. Thoroughly understanding and modeling the electronic transport in these devices will permit to improve their performance.

Second, a very fundamental topic. The host team has recently shown that absorption saturation can be engineered in the so called strong light-matter coupling regime [5], and has also provided its experimental proof [6]. In this regime too, the response is governed by coupled light-matter states called polaritons. However, what happens when the system is not a two-level quantum well, but a so called multisubband quantum well, is still unknown. The team is able to generate experimental data on this system, a perfect situation to develop a reliable modeling of this system.

Third: Effective Semiconductor Maxwell-Bloch equations for quantum cascade lasers.


1. A. Frisk Kockum, A. Miranowicz, S. De Liberato, S. Savasta, and F. Nori, "Ultrastrong coupling between light and matter," Nat. Rev. Phys. 1, 19–40 (2019).
2. C. Ciuti, G. Bastard, and I. Carusotto, "Quantum vacuum properties of the intersubband cavity polariton field," Phys. Rev. B 72, 115303 (2005).
3. Y. Todorov, A. M. Andrews, R. Colombelli, S. De Liberato, C. Ciuti, P. Klang, G. Strasser, and C. Sirtori, "Ultrastrong Light-Matter Coupling Regime with Polariton Dots," Phys. Rev. Lett. 105, 196402 (2010).
4. M. Malerba, S. Pirotta, G. Aubin, L. Lucia, M. Jeannin, J.-M. Manceau, A. Bousseksou, Q. Lin, J.-F. Lampin, E. Peytavit, S. Barbieri, L. H. Li, A. G. Davies, E. H. Linfield, and R. Colombelli, "Ultrafast (≈10 GHz) mid-IR modulator based on ultrafast electrical switching of the light–matter coupling," Appl. Phys. Lett. 125, 41101 (2024).
5. M. Jeannin, J. Manceau, and R. Colombelli, "Unified Description of Saturation and Bistability of Intersubband Transitions in the Weak and Strong Light-Matter Coupling Regimes," 187401, 1–7 (2021).
6. M. Jeannin, E. Cosentino, S. Pirotta, M. Malerba, G. Biasiol, J. M. Manceau, and R. Colombelli, "Low intensity saturation of an ISB transition by a mid-IR quantum cascade laser," Appl. Phys. Lett. 122, 241107 (2023).

Your Profil

Skills

From the description, the research project is theoretical, but the candidate must be able to be “close” to the experiments as she/he will evolve in an experimental group. It is possible that the candidate will be led to learn and perform some simple optical experiments. Most of the effort will be devoted to electronic transport, and quantum/electromagnetic numerical modeling towards device design and development. The successful applicant will be an energetic individual with interest in semiconductor device physics, and will have completed a graduate program in a related topic (Physics, Optics or Engineering).

Your Work Environment

Funding is provided by an ERC Advanced Grant.

The work will take place at the Center for Nanoscience and Nanotechnology, on the Plateau de Saclay.
The Center for Nanoscience and Nanotechnology (C2N) is a joint research unit of CNRS, Paris Saclay University, and Paris Cité University. The C2N, with approximately 410 staff, is located in Palaiseau (91), at the heart of the Paris Saclay campus.
C2N encompasses four scientific departments (photonics, materials, nanoelectronics, and nanobiofluidic microsystems). This position is located within the photonics department.

Constraints and risks

N/A

Compensation and benefits

Compensation

between 3081.22 Euros and 4291.70 Euros gross salary

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.

CNRS

The research professions