Imma Perfetto
Cosmos science journalist
Researchers have successfully controlled multiple mechanical oscillators at the quantum level for the first time, a capability essential for creating more powerful quantum systems.
Mechanical oscillators turn energy into periodic oscillation. They’re at the heart of all quartz watches, for example. In the quantum realm, macroscopic oscillators could enable ultra-sensitive sensors and quantum computing components.
But collective quantum behaviour, where many oscillators act as one, is challenging to achieve because to do so requires near-perfect (identical) units.
Now, researchers have finally managed it: they successfully prepared 6 mechanical oscillators in a collective state, observed their quantum behaviour, and measured phenomena that only emerge when oscillators act as a group.
“This is enabled by the extremely low disorder among the mechanical frequencies in a superconducting platform, reaching levels as low as 0.1%,” says Mahdi Chegnizadeh of Ecole Polytechnique Fédérale de Lausanne in Switzerland (EPFL), the first author of the new study published in the journal Science.
“This precision allowed the oscillators to enter a collective state, where they behave as a unified system rather than independent components.”
To observe the quantum effects, the researchers used a technique called sideband cooling to reduce the energy of oscillators to their quantum ground state (the lowest possible energy allowed by quantum mechanics).
By shining laser light tuned slightly below the oscillator’s natural frequency the light’s energy interacts with the vibrating system in a way that subtracts energy from it, reducing thermal vibrations and bringing oscillator to near stillness.
“By preparing the collective mode in its quantum ground state, we observed quantum sideband asymmetry, which is the hallmark of quantum collective motion,” says Marco Scigliuzzo, a co-author of the study also from EPFL.
“Typically, quantum motion is confined to a single object, but here it spanned the entire system of oscillators.”
