They created the fifth state of matter for the first time!

About 100 years ago, Satyendra Nath Bose and Einstein predicted that at a cold point, near absolute zero, the particles that make up a gas would begin to share certain properties and behaviors. It took 70 years to create this state, a Bose-Einstein condensate (BEC).

Now, 30 years later, we have discovered new ways to deal with this phase. Thanks to the creation of a Bose-Einstein dipolar condensate of sodium and cesium (NaCs) molecules. This is the first time that a condensate has been achieved with this feature and could open a new window into physics.

Bose-Einstein condensates are called the “fifth state” of matter, after solids, liquids, gases, and plasmas. As the team behind the study explains, BECs are achieved when the temperature of gas molecules becomes so low that their wave functions overlap. When this happens, the material undergoes a phase transition (similar to familiar transitions like evaporation). These condensates make it easier to analyze the quantum properties of matter on a scale more manageable than the atomic level.

The first BECs were created with atomic gases (rubidium or sodium gases), but since 2008 labs have been making them with diatomic molecules such as potassium rubidium. The new study also relies on a diatomic sodium-cesium molecule. They were able to cool it to five nanokelvins, five billionths of a degree above absolute zero (0 K or -273.15 degrees Celsius).

Last year, the team behind the study published another paper in which they laid the groundwork for the “trick” they used to cool the gas to these temperatures. This “trick” (counterintuitive as it may seem) is found in microwaves.

In this case, the microwaves are not used to vibrate the molecules and thus heat them up, but rather to prevent them from colliding with each other. In this way, the team was able to remove the hotter molecules, preventing them from colliding with the cooler ones. Only the colder molecules remained in the gas, “like blowing on a coffee cup,” as the team described it. In this way, they were able to lower the temperature of the gas enough to achieve this phase change.

Why is this happening? According to the team, this new technique allows us to control the strength with which we want the BEC particles to interact. This will make it possible to simulate strong quantum interactions, such as those between electrons. They add that this would allow for the exploration of different phenomena on this scale, such as new types of superfluids. It could also be used to turn these particles into “simulators” that mimic the quantum properties of other materials.

source