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| The Glass Nanosphere Appearing in Green Levitating In The Centre Of The Optical Trap. Image Credit: ETH Zurich |
ETH Zurich researchers used laser light to lift a glass nanosphere and slow its motion to its simplest quantum mechanical state. This achievement could help us better comprehend quantum mechanics by bringing it closer to human scale and allowing it to be used in a wider range of technologies.
In an
optical trap, a sphere with a diameter of 100 nanometers was made to levitate.
It's suspended in mid-air thanks to a laser. The trap is contained in a vacuum
container and is kept at a temperature just above absolute zero.
Despite
this, the sphere is still not in a quantum state due to its excessive energy.
The team utilises another laser and the light reflected by the sphere to slow
it down even more. This produces an interference pattern, and the team can
adjust the laser so that the light pushing and tugging on the sphere causes it
to slow down and return to its original state.
In a
statement, senior author and Professor of Photonics Lukas Novotny said, "This
is the first time that such a technology has been utilised to control the
quantum state of a macroscopic object in free space."
Similar
procedures have been used in optical resonators, but this method allows for
complete isolation of the sphere after the interference laser is turned off.
This permits the sphere's quantum wave to freely expand. Something very
fantastic is coming ahead. This nanosphere, like electrons and photons, is both
a wave and a particle. It may be able to test it using double-slit tests in the
future and witness the expected interference pattern.
"For
the time being, however," Novotny added, "that's just a pipe
dream."
Such an
approach's applications could be revolutionary. Researchers reported just last
month that they had successfully brought the 10-kilogram (22-pound)
optomechanical oscillator generated by the LIGO gravitational wave
observatory's mirrors close to its quantum ground state. It's critical to get
this level of "stillness" in larger and larger objects if you want to
make better sensors.
Quantum
sensors that use interfering atomic waves to measure the slightest
accelerations or rotations are already in use. The sensor becomes more
sensitive as the interfering item grows in size. As a result, having
nanospheres or larger objects could be a game-changer for ultra-precise
measurements.
References:
Quantum control of a nanoparticle optically levitated in cryogenic free space https://www.nature.com/articles/s41586-021-03617-w
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