laboratoire pierre aigrain
électronique et photonique quantiques
 
laboratoire pierre aigrain
 

Coherent and nonlinear optics

PhD proposals


Quantum optics with colored centers in diamond

Projet scientifique
Over the past twenty years remarkable progress has been made in isolating single quantum systems and controlling the coupling to their environment. A lot of efforts were undertaken using ultra-cold single trapped atoms for reaching these goals. Amongst the most recent experimental realizations one can list the demonstration of 14 entangled ions, their use as quantum simulators, the generation of long distance entanglement between atoms, the realisation of ultra-stable clocks and the observation of pristine quantum-electrodynamical effects. Inspired by these developments, nitrogen vacancy (NV) defects in diamonds are now reaching a degree of control that will enable most of these above experiments to be soon realised in a solid state environment.

We intend to transfer part of the knowledge developed over the past decades in the field of single ultra-cold atoms to NV centres in diamonds, with the prospect of being in a position to perform fundamental investigations of quantum electrodynamics and metrology and for operations that are needed for quantum communication in the solid state. Along this project, the tools to realize hybrid platforms comprising of spins in diamonds interacting with single photons will be developed together with fundamental quantum optical experiments.

The student must have a strong background in solid state physics and experimental optics and a strong motivation for experimental work.

Methods and techniques : Micro-photoluminescence spectroscopy, lasers, cryogeny, clean room, vacuum techniques...

Contact : Gabriel Hétet

Hot carriers in graphene and van der Waals heterostructures

Projet scientifique
Graphene is a very promising material for future electronics. Among its most attractive properties stands the outstanding electron mobility reflecting the weak coupling of electrons to the lattice. The study of the ultimate mechanisms that determine this coupling and electron energy relaxation is at the heart of major technological challenges. These mechanisms also make it possible to explore new physics related to the particular dispersion relations of electrons and phonons and to their two-dimensional character. The ideal setting to study these phenomena is the high frequency nano-transistor, with graphene as conduction channel. Furthermore, the ability to optically access the conduction channel opens many opportunities to probe or control the electron-phonon coupling. The laboratory Pierre Aigrain ENS has developed this research at the interface between the activities of optics and mesoscopic physics groups: the goal is to understand how light can modulate the electronic properties of graphene transistors or conversely how the the microscopic processes can generate specific optical signatures (luminescence, Raman scattering ...). More recently, new two-dimensional materials having the same crystallographic structure as graphene (transition metal dichalchogides as MoS2,...) have been discovered and used to combine the application of the alternating monolayers metal, or insulating semiconductor for considering new optoelectronic devices to the ultimate properties photo-detection, energy conversion or light emission. The candidate will have solid bases physics of condensed matter and a real taste for nano-fabrication and testing combining optical spectroscopy techniques and radio-frequency electronics.

Techniques utilisées : Nano-fabrication, transport, rf, optical spectroscopy, etc.

Qualités du candidat requises : Connaissances en physique des nanostructures, physique quantique. Compétences en optique expérimentale.

Rémunération éventuelle du stage : OUI, uniquement pour des étudiants non rémunérés par ailleurs et pour une durée de stage supérieure à 2 mois.
Possibilité de poursuivre en thèse ? OUI, fortement recommandée

Contact : Christophe Voisin, Emmanuel Baudin

TeraHertz detection using semiconductor microcavities

Projet scientifique
The THz frequency range (1 THz = 1012 Hz = 4.1meV) lies between microwaves and mid-infrared and present interesting application possibilities in various fields such as medicine, security imaging, non-destructive control or gas detection. Despite this potential, it remains largely unexplored due to limited efficiency, prohibitive sizes or costs of detectors and emitters.

We have recently developed a THz detector based on the electric dipole transition of asymetric quantum wells in strong coupling with a semiconductor microcavity [1]. Compared to existing devices, this approach is not fundamentaly limited to a low temperature regime, which is usually necessary to avoid parasitic thermal transitions which easily mask the radiative transitions of interest. This is possible thanks to the short lifetime of the fundamental excitations (polaritons) at stake in the THz transition whose temperature is arbitrarily low as they deintegrate radiatively before thermalizing with the cristal.

During this internship, the optical and THz properties of the heterostructures we have developed will be characterized at low temperature, using a Ti:Sa monomode laser and a quantum cascade laser as a source. The various regimes of this THz detector will be studied.

[1] S. Huppert, O. Lafont, E. Baudin, J. Tignon, and R. Ferreira, Terahertz emission from multiple-microcavity exciton-polariton lasers, Phys. Rev. B 90, 241302 (2014)

Techniques utilisées : optical spectroscopy, cryogeny, electronics.

Qualités du candidat requises : Connaissances en physique des nanostructures, physique quantique. Compétences en optique expérimentale.

Rémunération éventuelle du stage : OUI, uniquement pour des étudiants non rémunérés par ailleurs et pour une durée de stage supérieure à 2 mois.
Possibilité de poursuivre en thèse ? OUI, fortement recommandée

Contact : Emmanuel Baudin