The project focuses on mixtures of electrons (fermion) and excitons (electron-hole pair, a boson) in a new class of materials: van der Waals heterostructures. The latter can be seen as a “mille-feuille”, obtained by stacking atomically thin sheets of various materials. They recently became a prominent platform to study many-body physics, after a milestone discovery of superconductivity in bilayer graphene. Our long term ambition is to introduce superconductivity in a controlled manner, using excitons as force-carrier bosons (instead of phonons in conventional superconductors). The internship will pave the way toward this goal. It includes two steps, (i) the fabrication of the heterostructures and (ii) a first characterization with optical spectroscopy.

Quantum imaging exploits non-classical light to outperform classical methods in resolution, sensitivity, or to enable new modalities. Our team has recently developed an approach that encodes images in the correlations of entangled photon pairs, making them invisible to standard intensity measurements but retrievable through coincidence detection with advanced single-photon cameras. Using this technique, we demonstrated image transmission through scattering layers in conditions where classical light fails. This M2 internship (with the possibility of continuing as a PhD) builds directly on these results. The setup will be upgraded with a digital micromirror device and an event-based camera to move toward real-time operation. The project will then explore new applications, such as exploiting the intrinsic nonlinearity of quantum imaging for advanced image processing or photonic computing, and investigating secure image transmission schemes based on entanglement. The student will actively improve the system’s performance, study the underlying physics, and help identify promising research directions through both experiments and simulations. More infos: www.quantumimagingparis.fr

Quantum entanglement underpins technologies in communication, computing, and imaging, but its fragile nature makes it highly sensitive to optical disorder such as turbulence or scattering. This limits the performance of many quantum protocols and poses a major challenge for real-world applications. In collaboration with Prof. Gigan’s group at LKB, we investigate how entangled photons propagate through complex media and develop methods to preserve and control their quantum properties. We have shown that wavefront shaping, originally designed for classical light, can compensate for scattering and enable entanglement transmission through diffusive layers. Surprisingly, disorder can also be exploited: we demonstrated Bell inequality violations through multimode fibers, opening new perspectives for entanglement distribution in networks. Building on these results, this Master’s internship (with the possibility of continuing to a PhD) will focus on transmitting complex entangled two-photon states (e.g. polariation, space, spectral) through highly scattering media. The project will develop a novel multi-plane wavefront shaping strategy, inspired by multi-plane light converters, combining the expertise of Dr. Defienne’s team in quantum imaging with Prof. Gigan’s advances in wavefront shaping. More infos: www.quantumimagingparis.fr

Recent progress in the field of quantum thermodynamics allowed to define and analyze work and heat exchanges between quantum systems, and extend the Second law to nonequilibrium ensemble of quantum systems. However, applying those definitions to concrete situations require to keep track of the full state of the systems, which is intractable for large quantum systems. The intern will join the effort of the group to build a formalism for nonequilibrium quantum thermodynamics involving only a few macroscopic observables, relevant for numerical or experimental analysis of many-body systems. To do so, the intern will apply the concepts developed in the group to paradigmatic examples of many-body quantum systems, whose dynamics is either analytically or numerically solvable, to help identify the best formulations of the theory being developed. The internship might be pursued with a PhD in the group funded via a European ERC project.

We study how spatial modulation of tunnel couplings in one-dimensional systems can open electronic band gaps and host edge states, as in the Su–Schrieffer–Heeger (SSH) model. Beyond fundamental physics, controlling such gaps is attractive for quantum technologies, since they can protect fragile quantum states from decoherence. Recently, our team demonstrated electrical control of a band gap in a suspended carbon nanotube using an array of 15 gates. By applying alternating electrostatic potentials, we achieved tunable gaps up to 25 meV, directly visible in transport spectroscopy. The internship (with possible continuation as a PhD) will build on this result by probing the system with microwave photons in a mesoscopic QED setup. Using a new readout technique based on cavity dipole radiation activated by rf-gates, the goal is to reveal edge states and move toward SSH-type physics. The project combines quantum transport and microwave engineering in close collaboration with the startup C12. Candidates should have a strong background in quantum/condensed matter physics and an interest in nanodevices and advanced measurement methods.

The goal of this experimental internship is to follow in real time the bond formation of two isolated species initially separated in an ultracold (0.37K) superfluid solvent. For this purpose, we will use ultrashort laser pulses to trigger, track and characterize the reaction following a pump-probe methodology. In practice, we will rely on time-resolved photoionization spectroscopy, a technique based on the ionization of the species by the laser pulses and on the detection of the electrons and ions as molecular probes. The electron carries information about the initial electronic state of the ionized species, while the ion reveals the final state after relaxation processes such as fragmentation or isomerization.

The internship is focused on charge density waves —macroscopic quantum states consisting in a coherent spatial modulation of the charge in a crystal— and how they can experience a proximity effect, i.e. live in a crystal that does not naturally develop such quantum phases but can host them when put in contact to another crystal. This effect will be studied in two-dimensional crystals, and will be scrutinized using cryogenic optical spectroscopy and electron diffraction.

The goal of this internship is to develop a unique combination of a scanning tunneling microscope, an optical microscope, and a Hanbury Brown and Twiss (HBT) interferometer for photon correlation measurements. Using this unique instrument, cutting-edge nano-optics experiments on plasmonic nanostructures coupled to quantum emitters will be performed. The tunneling current under the STM tip will be used as a source of local electrical excitation of the surface plasmons. The light produced will be collected using the optical microscope, and the photon bunching and anti-bunching effects will be demonstrated using the HBT interferometer (i.e. measuring the second-order correlation g(2) function of light). The internship includes a significant experimental component and instrumental development

Two-dimensional semiconducting materials, such as transition metal dichalcogenide (TMD) monolayers, are key in the development of future device technologies. This is because such materials are only a few atoms thick and have unique optical and electronic properties. TMD monolayers are also considered an ideal platform for the study of excitons, i.e., bound electron-hole pairs, in 2D materials. Controlling the generation of excitons, their radiative decay, and their interactions with free charge carriers in 2D semiconductors is crucial for applications, e.g., in photovoltaic and light emitting devices. In this Masters thesis, the student will use nano-optical tools to probe the excitonic properties of TMD monolayers on the nanometer scale. The tunneling current between the sample and the tip of a scanning tunneling microscope (STM) will serve to locally excite the electroluminescence of the 2D semiconductor. The resulting light will be analyzed using optical microscopy and spectroscopy. Moreover, the student will carry out cutting-edge nano-optics experiments using the STM on “twist-engineered” heterostructures of these TMD monolayers. As has been recently discovered, new material properties may appear in such layered heterostructures depending on the misalignment angle (or “twist”) between adjacent layers.

The chiroptical response of materials and structures is most often studied by optical means, yet in a future optoelectronic nanodevice, a local electronic excitation is necessary. Working with this long-term goal in mind, we will investigate for the first time the electrical excitation of a chiral nanoparticle using the tunneling current from a scanning tunneling microscope. We will also investigate chiral light-matter interactions of a 2D semiconductor in an electrically excited plasmonic cavity