David Vitali

Entangling two distant non-interacting microwave modes

A protocol able to prepare two remote and initially uncorrelated microwave modes in an entangled stationary state, which is certifiable using only local optical homodyne measurements id proposed. The protocol is an extension of continuous variable entanglement swapping, and exploits two hybrid quadripartite opto-electro-mechanical systems in which a nanomechanical resonator acts as a quantum interface able to entangle optical and microwave fields. The proposed protocol allows to circumvent the problems associated with the fragility of microwave photons with respect to thermal noise and may represent a fundamental tool for the realization of quantum networks connecting distant solid-state and superconducting qubits, which are typically manipulated with microwave fields. The certifying measurements on the optical modes guarantee the success of entanglement swapping without the need of performing explicit measurements on the distant microwave fields.

Entanglement in macroscopic optomechanical systems

We consider an optical cavity made by two moving mirrors and driven by an intense classical laser field. We determine the steady state of he optomechanical system and show that two vibrational modes of the mirrors, with effective mass of the order of micrograms, can be entangled thanks to the effect of radiation pressure. The resulting entanglement is however quite fragile with respect to temperature.

Force sensitivity of a cavityless optomechanical system

We study the possibility to reveal a weak coherent force acting on a movable mirror (probe) by coupling it to a radiation field (meter) in a cavityless configuration. We determine the sensitivity of such a model and we show that the use of entangled meter state greatly improves the ultimate detection limit. A comparison of the presented model with that involving optical cavity is also done.

Quantum effects versus thermal noise in optomechanical systems

We predict the appearance of purely quantum effects within a radiation field upon reflection on a movable mirror. The model of an optical cavity having an oscillating end mirror is employed, and the role of thermal noise associated to this mechanical motion is studied.