Research Highlight

Quantum state in a large object

doi:10.1038/nindia.2021.92 Published online 29 June 2021

An international team of physicists has come very close to observing the quantum ground state — the lowest state of energy — of a 10-kilogram suspended mechanical oscillator1

The oscillator, formed by the mirrors of the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US, is the largest object scientists have brought close to a quantum state by cooling it down to almost absolute zero.

The findings of this research raises the possibility of testing gravity on massive quantum systems, the researchers say.

To date, quantum states of motion have been observed in very tiny nanoscale objects. To realise the quantum state of a large object, the scientists, including researchers from the Massachusetts Institute of Technology (MIT) in the US and the Inter-University Centre for Astronomy and Astrophysics in Pune, India, set out to prepare the motion of the suspended oscillator at extremely low temperature. 

Every object, even at rest, has a temperature. This means that its atoms are constantly jiggling around. This jiggling motion is small, but invisible to the naked eye. Bringing object to complete rest requires it to be cooled down close to absolute zero. The researchers cooled down the oscillator to a temperature of 77 nanoKelvin by applying laser beams.

“This research shows that a large object, which started out being very well described by classical physics, was eventually prepared close to a state that can only be described accurately by quantum mechanics,” said MIT scientist Vivishek Sudhir, who directed the research.


1. Whittle, C. et al. Approaching the motional ground state of a 10 kg object. Science. 372, 1333-1336 (2021) Doi: 10.1126/science.abh2634