For the first time, researchers have transformed light into a "'supersolid" — a strange state of matter that is both solid and liquid at the same time.
Although scientists have made supersolids out of atoms before, this is the first instance of coupling light and matter to create a supersolid and it opens new doors for studying condensed-matter physics, researchers explained in a paper published March 5 in journal Science .
But what exactly is a supersolid, and why is this new development so exciting? Here's everything you need to know.
What is a supersolid?
Supersolids are a strange state of matter defined by quantum mechanics where particles condense into an orderly, crystalline solid but also move like a liquid that has no viscosity. (Viscosity refers to a substance's internal friction, governing how smoothly it flows). Usually, solids don't move on their own, but supersolids change direction and density depending on particle interactions while maintaining an organized lattice structure.
Why are supersolids so cold?
Supersolids require extremely low temperatures to form — usually very close to absolute zero (minus 459.67 degrees Fahrenheit, or minus 273.15 degrees Celsius). Most of the particles have to occupy the lowest energy state available, and heat makes particles jump up and down like excitable toddlers in a ball pit.
If a material is cold enough, the temperature no longer obscures how the particles interact with each other. Instead, the tiny effects of quantum mechanics become the defining factors in how the material behaves.
Picture this: the toddlers have left and the ball pit has quieted down. We now have the chance to examine undisturbed how the various elements within the ball pit interrelate, shaping its overall nature.
Related: 32 physics experiments that transformed our understanding of the world
In what way could a fluid possess zero viscosity?
Viscosity quantifies the ease with which a fluid can alter its form. Fluids possessing greater viscosity tend to adhere more closely together and thus oppose motion; for instance, syrup pours out slowly as opposed to the swift flow of water from a faucet. With the exception of superfluids and supersolids, all fluids exhibit some degree of viscosity.
The most well-known instance of a fluid without viscosity is helium chilled to temperatures just above absolute zero. Even at absolute zero, particles do not remain entirely stationary; instead, they exhibit slight movement due to the uncertainty principle In the instance of the helium-4 isotope, these particles move quite vigorously — so much so that a sample of helium-4 cannot freeze at absolute zero without approximately 25 atmospheres of pressure being exerted to compress the particles tightly together.
At absolute zero, Helium-4 exhibits unusual movements due to various quantum effects, leading to significant alterations in its behaviour. The liquid loses all friction (thus becoming non-viscous) and can easily escape from containers, along with displaying several other peculiar traits.
What methods can we use to turn light into a solid substance?
Supersolids have been made from atomic gases Previously. Nevertheless, the latest study employed a innovative approach that depends on the characteristics of "polariton" systems.
Polaritons arise from the interaction between photons (light) and quasiparticles such as excitons via robust electromagnetic forces. These entities exhibit characteristics enabling them to collapse into their minimum achievable energy level akin to certain atomic gases. Essentially, this process combines light with matter, resulting in both being able to form a supersolid when brought together.
Why are supersolids useful?
Supersolids are crucial for investigation as they reveal the impact of minuscule, quantum-level particle interactions free from thermal interference. By examining their properties and behaviors, we gain insights into the very construction of atoms and particles themselves. This research fundamentally enhances our understanding of the universe around us.
Through further study and innovation, supersolids might find applications in various fields. quantum computing , superconductors , seamless lubricants, and uses we've only just started imagining. The number of potential opportunities awaiting us remains vast — developing a supersolid from light represents significant progress.
