A new study published on 1st in the journal "Nature Physics" by an international research team from the UK, Switzerland, and Austria has established a novel platform to address the boundary problem between classical and quantum physics. This breakthrough represents a significant leap forward in understanding fundamental physics and offers hope for practical applications, particularly in sensor technology for environmental monitoring and offline navigation.
Two nanoscale particles trapped by optical tweezers are coupled together by photons bouncing back and forth between mirrors. Image source: University of Manchester, UK.
Over the past century, physicists have observed quantum phenomena in increasingly larger objects, from subatomic particles like electrons to molecules containing thousands of atoms. Recently, the field of optomechanics has been dedicated to controlling high-quality microscale objects in vacuum, hoping to test quantum phenomena in objects several orders of magnitude heavier than atoms and molecules, further pushing this limit. However, as the mass and size of objects increase, their quantum features, such as entanglement, tend to disappear into the environment.
To observe quantum phenomena on a larger scale and reveal classical-to-quantum transitions, quantum features need to remain unchanged in the presence of environmental noise. There are two ways to achieve this: suppressing noise or enhancing quantum features. The new research adopts the latter approach.
The study demonstrates that the interaction required for entanglement between two 0.1-micrometer-sized glass particles trapped by optical tweezers can be amplified by several orders of magnitude to overcome losses to the environment.
Researchers place the two particles between two highly reflective mirrors, forming an optical cavity. In this setup, photons scattered by each particle bounce back and forth between the mirrors thousands of times before leaving the cavity, significantly increasing the chances of interaction with the other particle. Since the optical interaction is mediated by the cavity, its strength does not decay with distance, allowing researchers to couple microscale particles within a few millimeters range.
The key advantage of suspended mechanical sensors over other quantum sensing systems lies in their higher mass, making them ideal for detecting gravity and acceleration with higher sensitivity, such as monitoring polar ice in climate research or measuring acceleration in navigation.
