A Bose-Einstein Condensate is a state of matter produced when particles called bosons are cooled to almost absolute zero, and it is sometimes referred to as the “fifth state of matter” (-273.15 degrees Celsius, or -460 degrees Fahrenheit).
Insufficient energy prevents the particles from moving into positions where their unique quantum features might interfere with one another at such low temperatures.  Without energy differences to distinguish the particles, the entire group develops a single quantum identity, thereby becoming a single “super-particle” cloud that follows its own rules.

Satyendra Nath Bose’s novel interpretation, which was confirmed by Albert Einstein, came to be known as Bose-Einstein statistics. This idea has become fundamental in mathematics and enables us to differentiate certain particles from one another when they are present in this super-particle cloud. In addition, Bose gave his name to a group of particles known as bosons, which is made up of particles that convey forces, including photons and gluons, and is part of the Standard Model of particle physics.

By extending Bose’s statistics to encompass atomic structure as well as light waves, Einstein was able to predict that when temperature decreased, groups of individual bosons may share quantum states. This was ultimately noticed in 1995 after an experiment successfully cooled a group of rubidium-87 atoms, which are big particles that can be classified as bosons, to 170 nanokelvin. For their contributions, physicists Carl Wieman, Wolfgang Ketterle, and Eric Cornell all shared the 2001 Nobel Prize in Physics.

Bose-Einstein Condensate From Quasiparticles

Now, scientists have produced the first Bose-Einstein condensate from quasiparticles, which are entities that are not elementary particles but have characteristics like charge and spin in common with them. For many years, researchers debated whether quasiparticles might experience Bose-Einstein condensation in a manner similar to that of real particles. Their conclusions may have important implications for developing quantum technology.

What are Quasiparticles ?

A subatomic particle, such as an electron or a proton, is replaced by a different subatomic particle with the same charge to create an exotic atom. For example, positronium is a rare atom made up of an electron and a positron, which is the positively charged opposite of an electron.

The exciton is another example. The energy of light striking a semiconductor is sufficient to excite the electrons, forcing them to move from an atom’s valence level to its conduction level. Light energy is converted into electrical energy by these excited electrons, which can freely move in an electric current. The hole that is left behind when negatively charged electrons make this jump can be handled as if it were a positively charged particle, with the negative electron and positive hole being drawn to and linked together.

This electron-hole pair is the electrically neutral quasiparticle known as an exciton. Quasiparticles nevertheless have elementary-particle characteristics like charge and spin despite not being one of the 17 elementary particles in the standard model of particle physics. Excitons come in two varieties: orthoexcitons, in which the electron’s spin is perpendicular to that of its hole, and paraexcitons, in which the opposite is true. Since exciton liquid droplets and other phases of matter have been produced using electron-hole systems, scientists have been investigating if they can produce a Bose-Einstein condensate from excitons.

Co-author of the study, “Observation of Bose-Einstein condensates of excitons in a bulk semiconductor,” and University of Tokyo physicist Makoto Kuwata-Gonokami said: “Since it was originally theoretically postulated in 1962, direct observation of an exciton condensate in a three-dimensional semiconductor has been avidly sought for.If quasiparticles could experience Bose-Einstein condensation in the same way as actual particles, this was a mystery. It represents the pinnacle of low-temperature physics.”

The goal of the current research is to better understand the dynamics of the collective excitations of the exciton Bose-Einstein condensate as it develops in the bulk semiconductor. To better understand the quantum physics of qubits, their main goal is to build a platform based on a system of these exciton Bose-Einstein condensates.