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