Scientists have achieved a breakthrough in quantum research by showing that nanoparticles can exhibit quantum rotational oscillations even at room temperature—without cooling them to near absolute zero.
Scientists have achieved a breakthrough in quantum research by showing that nanoparticles can exhibit quantum rotational oscillations even at room temperature—without cooling them to near absolute zero.
Using an elliptical nanoparticle, confined in an electromagnetic field, carefully calibrated lasers and mirrors were used to drain energy from its rotational motion until it reached almost the pure quantum ground state. Surprisingly, the particle itself remained hot—at a temperature of hundreds of degrees—but its spin was “frozen” in the quantum sense.
Exploring the limits of quantum physics
What are the limits of quantum physics? Scientists around the world have been exploring this question for decades. To harness quantum phenomena for technology, it is necessary to find out whether quantum behavior is possible not only in atoms and molecules, but also in objects much larger than them.
An example of this is microscopic glass spheres with a diameter of about 100 nanometers. Although each sphere is more than a thousand times larger than a grain of sand, on the quantum scale it is considered “large.” For years, researchers have tried to find out whether particles of this size can preserve quantum properties. Now, a team at ETH Zurich, together with theorists from TU Wien (Vienna), is reporting a significant discovery: proof that the rotational fluctuations of such particles obey quantum rules not only when they are cooled to almost absolute zero using very complex techniques, but also at room temperature.
Vibration quanta: only certain vibrations are possible
“A microscopic particle will always wobble a little,” says Carlos Gonzalez-Ballestero, from the Institute for Theoretical Physics at TU Wien. “The wobble depends on the temperature and how the environment affects the particle.”
In everyday life, any oscillation seems possible. A clock pendulum, for example, can swing at any angle and with different intensities. In the quantum world, things are different: at low energies, oscillations appear in discrete energy packets—“quanta of oscillation.”
There is a lowest vibrational state—the ground state—followed by a state with slightly more energy—the first excitation state, and so on. There are no “in-between” states, but a particle can be in a superposition—a quantum combination—of several vibrational states at the same time, a fundamental principle of quantum mechanics.
“It is very difficult to get a nanoparticle into a state where its quantum properties are prominent,” adds Gonzalez-Ballistero. “You have to ‘float’ it to isolate it as much as possible from disturbances. And you usually also need extremely low temperatures, close to absolute zero (-273.15°C).”
Quantum spin isolators in a hot particle
Now ETH Zurich and TU Wien have developed a method that allows a certain aspect of the nanoparticle to be brought into a quantum state—even though the entire particle is in a hot and messy state.
“We use a nanoparticle that is not perfectly spherical but slightly elliptical,” explains Gonzalez-Ballistero. “When you confine it in an electromagnetic field, it starts to spin. We asked: Can we observe the quantum properties of the spin oscillation? Can we extract energy from the spin motion until it is often in the quantum ground state?”
To do this, laser beams and an array of mirrors were used. “The laser can either add energy to the particle—or subtract it,” he says. “By properly aligning the mirrors, you can ensure that the probability of removing energy is high, and adding energy is low. This way, the rotational energy decreases until we get close to the quantum ground state.” To achieve this, it is necessary to solve difficult theoretical problems—in particular, to understand and properly control the quantum noise of the lasers.
Creating a state of quantum purity without cooling"
Ultimately, the researchers managed to bring the spin to a state that almost perfectly matches the quantum ground state. The amazing thing is that the nanoparticle itself is not cooled—on the contrary, it is very hot, hundreds of degrees.
“You have to distinguish between different degrees of freedom,” explains Gonzalez-Ballistero. “This way you can effectively reduce the energy of the rotational motion—without simultaneously reducing the internal thermal energy of the particle. Surprisingly, the rotation can ‘freeze,’ so to speak, even though the particle is hot.”
This creates a state that is “purer” in quantum terms than has previously been achieved with similar particles—without the need for cooling. “This is a surprisingly practical way to push the boundaries of quantum physics to the limit,” concludes Gonzalez-Ballistero. “We can now study quantum properties of objects in a stable and reliable way—something that was almost impossible before.”
More of the topic in Hayadan:
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Huge savings in energy spent on cooling close to absolute zero.
Response to this article: cool…
Response to the article on human sex fusion:
How long did the sixth day of creation last? I don't know. But it could certainly be the technical realization of the verse "And the Lord God formed man of the dust of the earth..." (Genesis, Chapter 2, Verse 7). As Rashi interprets: "Dust of the earth - gathered his dust from all the earth from the four winds..." (Rashi's commentary on the above verse)
What practical implications will this have?
An example of this is microscopic glass spheres with a diameter of about 100 nanometers. Although each sphere is more than a thousand times larger than a grain of sand, on the quantum scale it is considered “large.”
A thousand times bigger or a thousand times smaller?