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Spooky Quantum Effect That Turns Matter Invisible Finally Demonstrated

It has now been proven that a strange quantum phenomenon, which was predicted decades ago, exists: if you create a cloud of gas cold and thick enough, you can effectively turn it invisible.

Lasers were employed by researchers at the Massachusetts Institute of Technology (MIT) to compress and cool lithium gas to densities and temperatures low enough to reduce light scattering. They claim that the cloud will turn absolutely invisible if they can chill it down to absolute zero, or minus 459.67 degrees Fahrenheit (or minus 273.15 degrees Celsius).

The strange effect is the earliest known instance of Pauli blocking, a quantum mechanical phenomenon.

It prevents an atom from doing what all atoms would usually do: scatter light, according to research senior author Wolfgang Ketterle, a professor of physics at MIT. "What we've found is one very particular and basic kind of Pauli blocking," he said. The fact that this impact has been clearly observed for the first time indicates the emergence of a novel physics phenomenon.

The new method may be utilized to create materials that block out light so that information won't be lost in quantum computers.

The Pauli exclusion principle was developed in 1925 by renowned Austrian physicist Wolfgang Pauli and is where Pauli blocking gets its name. According to Pauli, no two so-called fermion particles, such as protons, neutrons, and electrons, may share the same space if they have the same quantum state.


The limited number of energy states at the lowest quantum level causes electrons in atoms to stack themselves into higher energy-level shells that circle atomic nuclei more and farther away from one another.

According to a 1967 study co-authored by the renowned scientist Freeman Dyson, without the exclusion principle, all atoms would collapse together while exploding in a tremendous burst of energy. It also prevents the electrons of different atoms from interacting with one another.


These results not only result in the stunning variety of the periodic table's elements but also stop our feet from penetrating the earth when we are standing on it and descending into the Earth's core.

The atoms in gas also fall under the exclusion principle. Even while atoms in a gas cloud are often fermions confined by the Pauli exclusion principle, there is typically enough room for them to leap into vacant energy levels for the principle to not greatly hamper their mobility.


Any atom that a photon, or light particle, collides with will be able to interact with it, absorbing its incoming momentum, recoiling to a new energy level, and scattering the photon away. This interaction occurs in a moderately heated gas cloud.

However, if you cool a gas down, the situation changes. As a result of the atoms' current energy loss, they fill all of the lowest possible states, creating a substance known as a Fermi sea. The particles can no longer migrate to higher or lower energy levels since they are encircled by one another.


According to the researchers, at this time they are piled in shells like sitting concertgoers in a sold-out auditorium and have nowhere to go if struck. The particles are so tightly packed that they can no longer interact with light. Pauli blocking ensures that any light that is sent in will simply pass through.

According to Ketterle, an atom can only scatter a photon if it can absorb the force of the kick by relocating to a different chair. "It can no longer absorb the kick and disperse the photon if all the other seats are filled. The atom, therefore, became transparent."

But achieving this condition in an atomic cloud is incredibly challenging. In order to record densities, it is necessary to compress the atoms in addition to having extremely low temperatures. The researchers captured their gas within an atomic trap for the delicate operation, then shot it with a laser.

The photons in the laser beam were calibrated in this case such that they only impacted with atoms traveling in the opposite direction from them, slowing them down and causing them to cool. The temperature at which the scientists' lithium cloud was frozen, at 20 microkelvins, was slightly above absolute zero.

The atoms were then compressed to a recording density of around 1 quadrillion (1 followed by 15 zeros) atoms per cubic centimeter using a second, precisely focused laser.

Then, using a hypersensitive camera to count the scattered photons, the researchers shone a third and final laser beam at their supercooled atoms to determine how shrouded they had become. This laser beam was precisely set to not change the temperature or density of the gas.

Their chilled and compressed atoms dispersed 38 percent less light than those at ambient temperature, as anticipated by their hypothesis, making them noticeably darker.

To demonstrate the phenomenon, two further independent teams cooled down the gases potassium and strontium. Pauli prevented excited atoms in the strontium experiment in order to prolong their time in an excited state. Pauli blocking was demonstrated in all three publications, which were all published in the journal Science on November 18.

Since the Pauli blocking effect has now been proven, scientists may now exploit it to create materials that block light.

Since quantum decoherence, or the loss of quantum information (delivered by light) to a computer's environment, currently hinders the performance of quantum computers, this would be extremely helpful.

Light scattering is an issue since it indicates that information is escaping your quantum computer whenever we manipulate the quantum environment, such as with quantum computers, according to Ketterle. This is one method of reducing light dispersion, and by doing so, we are advancing the overarching topic of atomic world control.

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