STAGE Manybody physics with light in semiconductor microcavities

Quantum simulation, first discussed by Richard Feynman [1], is an emerging experimental research field, which aims at understanding the eigenstates of quantum systems with many interacting particles. When the number of particles increases, the Hilbert space size diverges and the eigenstates are impossible to calculate with a classical computer. Richard Feynman proposed to learn about these eigenstates by realizing the experiment with a well-controlled artificial quantumsystem. While the most advanced platforms are cold atoms, trapped ions or superconducting loops, a very promising approach is to use photons in microcavities to realize such manybody quantum states. One advantage would be that multi photon entanglement could be imprinted on photons leaking out of the system, thus realizing a new source of quantum light. Our group at C2N has developed a unique expertise of designing lattices of coupled microcavities and pioneered the emulation of different Hamiltonians with these lattices [2]. We have realized the first topological
laser with a 1D lattice [3], explored Dirac physics with 2D honeycomb lattices [4]….
To induce photon-photon interactions and progress toward the simulation of manybody physics, we mix the cavity photons with electronic excitations, named excitons, created in quantum wells located in the cavity. The
resulting exciton-photon state, named cavity polaritons, shows significant interactions which have allowed demonstrating many fascinating properties such as superfluidity of light [5].
The challenge we propose now is to increase interactions to enter the strong quantum regime with single photon non-linearities. The work will start with the development and characterization of novel active materials, based on coupled quantum wells, which are expected to give rise to much
stronger interactions. These interactions will be measured by detailed low temperature spectroscopy and photon correlations. The smoking gun evidence for the quantum regime will be the measure of single photon emission. Then we will implement manybody Hamiltonians of increasing complexity building larger and larger lattices, and we will probe their quantum properties.
The work will be essentially experimental, with low temperature optical spectroscopy on micorcavity. The PhD student will participate to the processing of the samples, profiting from the unique technological environment that will be able in the new C2N clean room.