Optical levitation is a subfield of optomechanics, in which a nanoparticle is trapped in a vacuum at the focal spot of a microscope objective. Because levitated systems outperform other mechanical resonators, they offer the tantalizing prospect of investigating quantum mechanics at the mesoscale. To display quantum properties, the nanoparticle must be cooled down close to its ground state, which is typically achieved through the monitoring of its displacements and a modulation of the laser’s intensity. Currently, the most exciting endeavor in the field lays in performing levitation with many-body systems. Many-body levitation would offer the opportunity to observe effects for the first time, like the mesoscopic entanglement of nanoparticles. Sadly, conventional cooling techniques, cannot be multiplexed and fail badly to cool several elements in parallel. Throughout this internship, the candidate will experimentally implement a new cooling technique intended to achieve the first-ever cooling of a many-body system composed of multiple nanoparticles in levitation. Compared to former strategies, here, a spatial light modulator is used to spatially shape the wavefront of the laser beam. Such a modulation enables to exert simultaneously adapted optical forces on all the nanoparticles in order to reduce their individual vibrational motions, which ultimately leads to the cooling of the many-body system. A funding is available to continue this internship through a PhD.

Quantum information protocols are well defined mathematically, and there exist different benchmarks for establishing the necessary resources for potential quantum advantage, as for instance the discrete Wigner function negativies or "magic". At the same time, physical systems, and in particular, bosonic systems - as the quantum electromagnetic field - can be used to encode quantum information or, alternatively speaking, simulate quantum informational protocols. Nevertheless, for such systems, the "magical" resources enabling quantum advantage over classical simulations - i.e., enabling the efficient simulation of quantum protocols - are subjected to physical constraints, as symmetries and conservation laws. While abstract qubits have no particular symmetry, photons are bosons, symmetric identical particles. During this internship, we will address the interplay between physical and informational resources to determine how detection may be seen as a non-classical resource in quantum optics based quantum information protocols. This will be done by constructing a original framework where the phase reference of quantum optical states is explicitly treated as a resource. In general, this resource is implicit and disregarded, obscuring the assessment of the resource tradeoff of bosonic quantum information protocols. We will analyze, in particular, the role of detection in BosonSampling protocols and in homodyne detection, that is usually considered as resourceless.

See pdf file for all the details Extreme brief summary: The goal of the internship is to develop electrically reconfigurable meta-surfaces whose optical properties, in reflection/ absorption, can be addressed electrically on ultra-fast timescales. In particular, we target ultra-fast amplitude modulators for the mid-infrared spectral range. These developments are crucial for applications such as laser phase stabilization, spectroscopy, frequency comb generation, mode-locking, optical communications.

The goal of the internship is to develop an optical spectroscopy technique that is spatially resolved at the nanoscale, which is known as tip-enhanced photoluminescence (TEPL). This technique employs a laser beam focused onto the apex of a plasmonic metal tip (gold or silver) within an atomic force microscope (AFM) or scanning tunneling microscope (STM). To maximize the field enhancement effect at the tip apex, the focused beam must be radially polarized. To achieve this specific polarization, the intern will use a liquid-crystal polarization converter. The intern will then couple this beam to the plasmonic tip of an AFM or STM microscope, contribute to developing the software interface for controlling the optical detectors, and conduct TEPL experiments on semiconductor nanomaterial samples.

The objective of the internship and the thesis is to investigate the combined effect of nonlinearities and complex interferences in these optical graphs, particularly regarding the formation and dynamics of soliton states. In a second time, we will inject non-classical light (squeezed light or entangled photons) to test if entanglement is sensitive to chaos.

Photonic time crystals -optical systems that are strongly and periodically modulated in time- have recently emerged as a novel paradigm for controlling light–matter interactions through temporal modulation, analogous to how conventional spatial photonic crystals manipulate light through spatial structuring. Building on our recent demonstration of a photonic time crystal using a plasmonic metamaterial operating at Terahertz frequencies, this internship aims to lay the groundwork for realizing a quantum plasmonic metamaterial time crystal, that is a photonic time crystal that can operate in the few-photon regime. This will require developing a Terahertz spectroscopy setup with extended frequency coverage as well as the design and characterization of advanced plasmonic metamaterials.

In this project we will (1) locally and electrically excite chiral plasmonic nanoparticles and (2) to use them to enhance the chiral properties of a new class of two-dimensional (2D) semiconductors called transition metal dichalcogenides (TMDCs), which are key for a new branch of physics and technology called valleytronics