Scientists on Wednesday said that they have successfully stirred a strange matter called a “supersolid” – which is both rigid and fluid – for the first time, providing direct proof of the dual nature of this quantum oddity.

In everyday life, there are four states of matter – solid, liquid, gas, and the rarer plasma.

But physicists have long been investigating what are known as “exotic” states of matter, which are created at incredibly high energy levels or temperatures so cold they approach absolute zero (−273.15 degrees Celsius or-459.67 degrees Fahrenheit).

Under the right circumstances, electrons can actually “freeze” into a bizarre solid form. Now, physicists at Berkeley Lab have created and taken the first ever direct images of this structure.

At low temperatures and densities, groups of electrons can crystallize into a solid form known as a Wigner crystal, named after theoretical physicist Eugene Wigner who first predicted their existence in the 1930s. It was only a few years ago that scientists first directly detected and imaged them.

Now, a team has for the first time imaged a new quantum phase of electrons – a related structure called a Wigner molecular crystal. Basically, it’s the same solid electron phase, except that groups of electrons settle in each place on a lattice instead of single electrons.

Electrons typically travel at high speeds, zipping through matter unbound. In the 1930s, physicist Eugene Wigner predicted that electrons could be coaxed into stillness at low densities and cold temperatures, forming an electron ice that would later be called the Wigner crystal.

Researchers at Chalmers University of Technology in Sweden and at the University of Magdeburg in Germany have developed a novel type of nanomechanical resonator that combines two important features: high mechanical quality and piezoelectricity. This development could open doors to new possibilities in quantum sensing technologies.