Two Time Crystals Have Been Successfully Linked Together For The First Time

Physicists have just made an incredible breakthrough in the development of quantum gadgets that sound like something out of a science fiction movie.

For the first time, individual groupings of particles that behave like weird states of matter called time crystals have been connected into a single, dynamic system that might be extremely beneficial in quantum computing.

This is the next step toward possibly utilizing time crystals for practical uses, such as quantum information processing, following the first detection of the interaction between two time crystals, which was documented in a study two years ago.

Time crystals were supposed to be physically impossible until they were found and proven a few years ago in 2016. They're a type of substance that's extremely similar to regular crystals, but with one additional, unusual, and unique feature.

Atoms are organized in a set, three-dimensional grid pattern in regular crystals, similar to the atomic lattice of a diamond or quartz crystal. The layout of these repeating lattices can vary, but any movement they display is entirely due to external forces.

The atoms in time crystals act a little differently. They show patterns of movement throughout time that aren't simply explained by a push or shove from outside. These oscillations, which are referred described as 'ticking,' are fixed to a specific frequency.

Time crystals are stable and coherent over extended periods of time because they tick at their lowest possible energy level, known as the ground state. As a result, where the structure of regular crystals repeats in space, the structure of time crystals repeats in both space and time, resulting in permanent ground state motion.

"Everybody knows that perpetual motion machines are impossible," says Samuli Autti, physicist and principal author at Lancaster University in the United Kingdom.

"However, in quantum physics perpetual motion is okay as long as we keep our eyes closed. By sneaking through this crack we can make time crystals." 

Magnons are quasiparticles that make up the time crystals with which the team has been working. Magnons are not actual particles, but rather a collective excitation of electron spins propagating through a lattice of spins, similar to a wave propagating through a lattice of spins.

When helium-3, a stable isotope of helium with two protons but only one neutron, is chilled to one tenth of a degree below absolute zero, magons form. This produces a B-phase superfluid, which is a zero-viscosity fluid with low pressure.

Time crystals generated as spatially separate Bose-Einstein condensates containing a trillion magnon quasiparticles in this medium.

Bosons chilled to just a fraction above absolute zero create a Bose-Einstein condensate (but not reaching absolute zero, at which point atoms stop moving).

This leads them to fall to their lowest-energy state, moving extremely slowly and overlapping, resulting in a dense cloud of atoms that behaves like a single'super atom' or matter wave.

When the two time crystals were permitted to come into contact with each other, magnons were swapped. The oscillation of each of the time crystals was altered by this exchange, resulting in a single system that could operate in two separate modes.

Objects that can have more than one state exist in a mix of various states before being pinned down by a definite measurement in quantum physics. As a result, having a time crystal working in a two-state system opens up a wealth of new possibilities for quantum-based technology.

Time crystals are still a long way from being used as qubits, since there are a slew of challenges to overcome first. However, the puzzle pieces are beginning to fall into place.

A different group of scientists reported earlier this year that they had successfully manufactured room temperature time crystals that do not require isolation from their environment.

More complex interactions between time crystals, as well as precision control of them, will need to be created, as will the ability to see interacting time crystals without the need of cooled superfluids. However, scientists are optimistic.

"It turns out putting two of them together works beautifully, even if time crystals should not exist in the first place," says the researcher. "And we already know they also exist at room temperature."