Physicists have created the first two-dimensional super-solid material — exotic command stage It behaves like a solid and frictionless liquid at the same time.
Supersolids are materials that atoms They are arranged in a regular repeating crystal structure, but are also able to flow forever without losing any kinetic energy. Despite its peculiar properties, which seem to violate many well-known laws of physics, physicists have long anticipated it in theory — it first appeared as a suggestion in the work of physicist Eugene Gross as early as 1957.
Now, using lasers and ultra-cool gases, physicists have finally coaxed a supersolid into a two-dimensional structure, an advance that could enable scientists to crack the deeper physics behind the mysterious properties of the exotic matter phase.
Of particular interest to the researchers is how their two-dimensional supersolids will behave when they are rolled in a circle, along with the tiny vortices, or vortices, that will appear within them.
«We expect there will be a lot to learn from studying rotational oscillations, for example, as well as vortices that can exist within a 2D system much more easily than they do in 1D,» said lead author Matthew Norcia, a physicist at the University of Quantum Institute. Innsbruck Optics and Quantum Information (IQOQI) in Austria, to Live Science in an email.
To create a super solid, the team suspended a cloud of dysprosium-164 atoms inside optical tweezers before cooling the atoms to just above zero Kelvin (minus 459.67 degrees Fahrenheit, or minus 273.15 degrees Celsius) using a technology called laser cooling.
Normally shooting a laser at the gas will heat it up, but if the photons (light particles) in the laser beam are moving in the opposite direction to the moving gas particles, they can actually cause the gas particles to slow down and cool. After cooling the dysprosium atoms as much as possible with a laser, the researchers loosened the «grip» of their optical tweezers, creating enough space for the more energetic atoms to escape.
Since «warmer» particles vibrate faster than cooler ones, this technique, called evaporative cooling, leaves researchers only with their supercooled atoms; These atoms have transformed into a new phase of matter — A Bose-Einstein condenser: A group of supercooled atoms in the range of a hair absolute zero.
When a gas is cooled to a temperature close to zero, all of its atoms lose their energy, entering the same energy states. Since we can distinguish between similar atoms in a gas cloud only by looking at their energy levels, this equation has a profound effect: the once disparate cloud of vibrating, jumping, and colliding atoms that make up warmer gas then becomes, from a quantum mechanics point of view, completely identical.
This opens the door to some really weird things quantitative effects. One of the basic rules of quantum behavior, the Heisenberg Uncertainty Principle, says that you cannot know the position and momentum of a particle with absolute accuracy. However, after the condensed Bose-Einstein atoms stopped moving, all their momentum became known. This causes the positions of the atoms to become so uncertain that the places they are likely to occupy grow larger in area than the spaces between the atoms themselves.
Instead of separate atoms, the intervening atoms in the mysterious Bose-Einstein sphere act as if they were just one giant particle. This gives some Bose-Einstein capacitors the property of superfluidity — allowing their molecules to flow without any friction. In fact, if you were to move a glass of superfluid Bose-Einstein liquid, it wouldn’t stop spinning.
The researchers used dysprosium-164 (an isotope of dysprosium) because (next to its neighbor in the periodic table holmium) it is the most magnetic of any element discovered. This means that when dysprosium-164 atoms are supercooled, in addition to becoming superfluid, they also clump together in droplets, sticking together like tiny bar magnets.
By «fine tuning the balance between long-range magnetic interactions and short-range contact interactions between atoms,» Norcia said, the team was able to make a long, one-dimensional tube of droplets that also contain free-flowing atoms — a super-solid one-dimensionality. . This was their previous job.
To make the jump from 1D to 2D supersolid, the team used a larger trap and dropped the intensity of the optical tweezers’ beams in two directions. This, combined with keeping enough atoms in the trap to maintain a high enough density, finally allowed them to create a zigzag structure of droplets, similar to two 1D opposite tubes sitting next to each other, in a super-rigid 2D.
With the task of creating it behind them, physicists now want to use a two-dimensional super-solid to study all the properties that arise from the presence of this extra dimension. For example, they plan to study the vortices that appear and get trapped between the array droplets, especially since these vortex vortices of atoms, at least in theory, can spin forever.
This also brings researchers one step closer to the supersized, three-dimensional solids envisioned by early proposals like Gross, and even the strange properties they might have.
The researchers published their findings on August 18 in the journal nature.
Originally published on Live Science.