A team of scientists have witnessed for the first time ever the formation of quasiparticle. It is a rare phenomenon observed in solid materials, something that physicists have been struggling to do for decades. It is an incredible achievement that would revolutionise the way ultra-fast electrons are developed and further the development of quantum processors.
An example is an electron moving through a solid substance. As the electron travels, it generates polarisation in its environment because of its electrical charge. This ‘polarisation’ cloud follows the electron through the material, and together they can be described as a quasiparticle.
“You could picture it as a skier on a powder day,” explained one of the researchers, Rudolf Grimm, from the University of Innsbruck in Austria. “The skier is surrounded by a cloud of snow crystals. Together they form a system that has different properties than the skier without the cloud.”
Quasiparticles and their formation have been extensively described in theoretical models but very little was possible in reality until this study. This was the case primarily because measuring and observing them in real time is difficult. Quasiparticle phenomena generally happen on a tiny scale and also it is short lived.
Grimm further said, “These processes last only attoseconds, which makes a time-resolved observation of their formation extremely difficult.”
1 attosecond is one-quintillionth of a second. 1 attosecond is to 1 second is what 1 second is to about 31.71 billion years – so, yeah, that’s pretty fast.
The team has managed to slow down the process. They used laser trapping techniques inside the vacuum chamber to create an ultracold quantum gas made up of lithium atoms and a small sample of potassium atoms in the centre.
Then the magnetic field was used to tune interactions of the particles, creating a type of quasiparticle known as a Fermi polaron. Fermi polaron is basically potassium atoms embedded in a lithium cloud.
Ultracold quantum gas has helped in slowing down the process to witness the formation of quasiparticles for the first time. “We simulated the same physical processes at much lower densities,” said Grimm. “Here, the formation time for polarons is a few microseconds.”
The team now is hoping to work on developing quantum processing systems that bring the super- fast electrons in the future.