Macroscopic Quantum Entanglement of Levitated Nanoparticles

Quantum mechanics is the theory of the microscopic world. It accurately describes atomic and molecular structures and the behavior of elementary particles. A hallmark of quantum mechanics is quantum entanglement, namely that two spatially separated objects behave as one single non-separable entity. Entanglement has been tested and verified with quantum systems, such as photons or atoms, and forms the basis for quantum teleportation and quantum information processing. However, entanglement of large objects is largely unexplored and it is not clear if there is a fundamental limit at large scales. This project aims to address this question with optically levitated nanoparticles consisting of more than a billion atoms. Two spatially separated nanoparticles will be trapped by a pair of focused laser beams and positioned into a laser cavity. The cavity ensures that the two particles interact via their own scattered light. By controlling the degrees of freedom of the lasers (intensity, polarization, frequency) and the position of the nanoparticles inside the laser cavity we will develop a procedure to establish motional entanglement between the two particles. This protocol will be developed in a synergistic approach between theory and experiment. The demonstration of quantum entanglement with massive objects enables the exploration of fundamental questions, for example, whether gravity requires a quantum description and whether the quantum description of nature breaks down at large enough length scales. Besides these fundamental questions, quantum entanglement with massive objects has potential applications in metrology and inertial force sensing (acceleration and rotation).