AMO Seminar - Nancy Gupta - University of Vienna

Towards experimental realisation of entanglement mediated by coulomb force under optimal feedback control

Optomechanics with levitated particles offers a powerful platform to explore quantum physics at macroscopic scales, including ground-state cooling. A major outstanding goal is to entangle the motion of two levitated nanoparticles, creating a genuine quantum state to study decoherence mechanisms. However, weak interactions between particles have so far prevented this. We address this challenge by employing electrostatic (Coulomb) interactions between two optically trapped silica nanoparticles. We systematically study active and passive charging methods and demonstrate strong coupling with an interaction strength reaching 12% of the mechanical frequency (g = 0.12\omega). We also achieve ground-state cooling and readout of the coupled normal modes.

Since steady-state entanglement still requires significantly stronger coupling, we propose a protocol based on optimal quantum control of continuously measured systems with time-dependent interactions. This approach relaxes the coupling requirements and enables unconditional entanglement under current experimental conditions. I will talk about the stabilisation of the strongly coupled system, feedback control of the normal modes, and the impact of non-markovian noise near the ground state.

Host: David Moore