Physicists have frozen 100 million atoms at room temperature

Scientists from Austria and the United States were able to catch a particle consisting of 100 million atoms using a laser and almost make it stop at room temperature. The particle was in the main quantum state with an effective temperature of 12 microkelvins. The work is published in the journal Science.

It is known that microscopic objects the size of a couple of atoms are described by the laws of quantum mechanics. Such objects can naturally be used in quantum technologies: when designing highly sensitive sensors or simulators of complex macroscopic systems. However, creating large coherent objects that consist of millions of atoms is an open problem today.

Physicists at the University of Vienna and MIT created a macroscopic superposition inside a silicon dioxide particle that contained 100 million atoms. Scientists placed the particle in a resonator using optical tweezers — a device that uses a powerful enough laser to hold an object in a fixed position in space with an accuracy of several nanometers.

Using frequency analysis of the resonator, physicists measured the energy of the particle’s motion and its temperature, as well as the lifetime of this state. Thanks to the precise selection of parameters of the optical tweezers, the researchers forced the particle to be in the main quantum state with the lowest possible energy.

The effective temperature of the cooled object was only 12.2 ± 0.5 microkelvin, and the average number of phonons was 0.43 ± 0.03. The number of phonons characterizes the energy of the mechanical movement of a particle — this is the first time that physicists have managed to achieve such a small number at room temperature. The lifetime of the created state was 7.6 ± 1 microsecond.

In further experiments, the researchers plan to increase the coherence time of the system by using more advanced resonators.

Physicists conducted an experiment opens up the possibility for macro-quantum physics. This, in turn, will help in creating high-precision detectors, including dark matter detectors. In addition to technical applications, such systems can help physicists identify quantum effects in gravity.

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