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Scientists put the quantum freeze on human-scale object

MIT scientists cooled a 22-pound object to a near quantum state standstill using the Laser Interfrometer Gravitational-wave Observatory's four 88-pound mirrors. Photo by Caltech/MIT/LIGO Lab
MIT scientists cooled a 22-pound object to a near quantum state standstill using the Laser Interfrometer Gravitational-wave Observatory's four 88-pound mirrors. Photo by Caltech/MIT/LIGO Lab

June 17 (UPI) -- For the first time, scientists have brought a human-scale object to a near standstill, turning the Laser Interfrometer Gravitational-wave Observatory's four mirrors into a quantum object.

The research team, led by quantum physicists at MIT, detailed their feat in a new paper, published Thursday in the journal Science.

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Most everything and everyone is constantly buzzing with motion. Even people and objects that appear to be still feature trillions of atoms vibrating with energy.

To quell this energy, scientists sometimes super-cool objects to what's called a "motional ground state." So far, scientists have only managed to bring very small objects, like a small cloud of atoms or nanogram-scale object, into a pure quantum state.

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"A pure quantum state is one whose characteristics cannot be explained by classical physics," study co-author Vivishek Sudhir, assistant professor of quantum mechanics at MIT, told UPI in an email.

To bring a large object into a pure quantum state and approaching its motional ground state, researchers must first be able to precisely measure the movement of its atoms.

If scientists can quantify the scale and direction of an object's motion, they can apply the necessary pushback to quiet its atoms.

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That's why scientists chose to put the quantum freeze on LIGO, which derives its optical powers from the ability to precisely measure the motion of its four mirrors.

When one-off measurements are made with lasers, the simple ping of an incoming photon can later the motional state of the target.

But when an object is being continuously measured, as is the case with LIGO and its four mirrors, the later photons recoil effect of earlier photos can be measured and accounted for using the data captured by later photons.

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After precisely recording the quantum and classical disturbances affecting each of the four mirrors, researchers attached electromagnets to the back of each mirror to apply equal and opposite forces, bringing the four mirrors to a near standstill.

"By precisely tracking those fluctuations, and applying a force to oppose it, we do bring that motion to a state very close to complete rest," Sudhir said.

Researchers estimate their breakthrough will allow them to measure the effects of gravity on quantum states.

"One of the questions that we might be able to answer is: 'Why do large objects not naturally appear in quantum states?' There are various conjectures for why that might be; some say that gravity -- which acts strongly on larger objects -- might be responsible," Sudhir told UPI.

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"We now have a system where some of these conjectures can be experimentally tested," Sudhir said.

In future experiments, scientists hope to put human-scale objects into other exotic quantum states.

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