New phase of matter in 2D discovered, defies normal statistical mechanics

Physicists at the Cavendish Laboratory in Cambridge have successfully produced the first two-dimensional Bose glass, an unusual phase of matter that defies conventional ideas in statistical mechanics.

To achieve this, the researchers used overlapping laser beams to generate a quasiperiodic pattern. Unlike a traditional crystal, which repeats periodically, this pattern exhibits long-range order without repetition, similar to a Penrose tiling.

When they introduced ultracold atoms—cooled to near absolute zero, at nanokelvin temperatures—into this structure, the atoms arranged themselves into a Bose glass.

“Localisation is not only one of the toughest nuts to crack in statistical mechanics, it can also help to advance quantum computing,” said Professor Ulrich Schneider, Professor of Many-Body Physics at the Cavendish Laboratory, who led the study.

Could this be significant for quantum computing?

As its name implies, the Bose glass exhibits certain glass-like properties, with all particles in the system becoming localized. This means that each particle remains confined to its position, without interacting or blending with its neighbors.

If coffee behaved in this way, for example, stirring milk into it would result in a permanent pattern of black and white stripes that never mix into a uniform color.

In a localized system like the Bose glass, particles don’t mix with their environment, which suggests that quantum information stored within such a system could be retained for much longer periods. This property has significant implications for quantum computing and information storage.

“A big limitation of large quantum systems is that we can’t model them on a computer,” said Schneider.

“To accurately describe the system, we have to consider all its particles and all their possible configurations, a number that grows very quickly. However, we now have a real-life 2D example which we can directly study and observe its dynamics and statistics.”

Schneider and his team specialize in quantum simulation and the dynamics of quantum many-body systems. They employ ultracold atoms to explore complex many-body effects that cannot be accurately simulated using current numerical methods, given the limitations of existing quantum computers.

Exploring potential application

In the experiment, the researchers witnessed an unexpectedly sharp phase transition from a Bose glass to a superfluid, similar to how ice melts as the temperature rises.

They describe a superfluid as a unique state of matter where fluid flows without any resistance. If particles were to move through a superfluid, they would experience no friction and would not slow down. This phenomenon, known as superfluidity, is closely connected to superconductivity .

Both the Bose glass and the superfluid are distinct phases of matter, much like ice and liquid water. However, in this experiment, atoms can form both phases simultaneously, akin to ice cubes floating in water.

The experimental findings, which align with recent theoretical predictions, provide new insights into how the Bose glass forms and transitions. With this understanding, scientists can begin exploring potential applications for this phase of matter.

Despite the promising opportunities ahead, Schneider emphasizes the need for caution in approaching future developments. “There are many things we still don’t understand about the Bose glass and its potential connection to many-body localisation, both regarding their thermodynamics as well as dynamical properties. We should first focus on answering more of these questions before we try to find uses for it,” concluded Schneider.

The study has been published in the journal Nature .