Glass dust and light linked in quantum entanglement experiment

Scientists at the University of Florence have demonstrated a link between the motion of a glass nanosphere and light, a key step towards sustaining quantum links for future technologies. The team, led by Francesco Marin, a lecturer in Experimental Physics of Matter, suspended a glass sphere approximately 100 nanometres in diameter using laser light within an optical cavity.

“The most significant aspect is that the correlations are not confined to the cavity; they are transferred to the light that emerges from it and propagates through space,” says Marin, detailing how the nanosphere’s motion becomes linked to a light field capable of carrying information. Published in Science, the research confirms a quantum link with a separability parameter of 0.918 ± 0.029, and operates at room temperature, offering promise for quantum memory and networks.

Entangled Light and Nanosphere Motion Demonstrated in Optomechanical System

The experiment achieved a separability parameter of 0.918 ± 0.029, a value confirming the quantum link between the nanosphere’s movement and the transmitted light. Classical correlations cannot fall below unity, demonstrating a clear departure from expected behaviour. Researchers at the University of Florence suspended a 100 nanometre glass sphere within an optical cavity, using laser light to both isolate and manipulate its motion, a feat demanding precise control at an incredibly small scale.

This isolation allowed for the observation of stationary entanglement, meaning the quantum connection between the sphere and the light wasn’t a fleeting instance, but a sustained state lasting over 40 kilohertz. The stability of this entanglement at room temperature distinguishes this work from many prior quantum experiments, which often require extremely low temperatures to maintain quantum states.

This operational simplicity makes levitated optomechanical systems particularly promising for practical applications, including the potential for quantum memory and networks. The team employed two lasers with distinct functions: one to cool and stabilize the nanosphere’s motion, and the other to generate the quantum correlations essential for establishing entanglement. The implications of this research extend beyond simply demonstrating entanglement, as the correlations observed weren’t confined within the optical cavity itself.

Quentin Deplano adds, “Connecting a stationary material object with a ‘floating’ light field travelling through space opens up possibilities,” envisioning the nanosphere’s motion acting as a quantum memory capable of storing and releasing information for future computing architectures. This ability to control quantum states in a relatively massive object, a nanosphere, at room temperature also opens avenues for exploring fundamental physics. The team published their findings in Science, detailing the methodology and results of this innovative experiment and its potential to reshape our understanding of quantum phenomena.

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