Remote quantum entanglement between two micromechanical oscillators.

Abstract

Entanglement,an essential feature of quantum theory that allows for inseparable quantum correlations to be shared between distant parties, is a crucial resource for quantum networks 1 . Of particular importance is the ability todistribute entanglement between remote objectsthat can also serve as quantum memories. Thishas been previously realized using systems such aswarm2,3 and cold atomicvapours4,5, individual atoms 6 and ions7,8, and defects in solid-state systems9-11. Practical communication applications require a combination ofseveral advantageous features, such as a particular operating wavelength, high bandwidth and long memorylifetimes. Here we introduce a purely micromachined solid-state platform in the form of chip-based optomechanical resonators made of nanostructured silicon beams. We create and demonstrate entanglement between two micromechanical oscillators across two chips that are separated by 20 centimetres . Theentangled quantum state is distributed by an optical field at a designed wavelength near 1,550 nanometres. Therefore, our system can be directly incorporated in a realistic fibre-optic quantum network operating in the conventional optical telecommunication band. Our results are an important step towards the development of large-area quantum networks based on silicon photonics.