the cycle of decomposition and rebirth

Decomposition is implacable in the macroscopic world: broken objects do not assemble again. However, other laws are valid in the quantum world: new research shows that so-called quasiparticles can decompose and reorganize again and become virtually immortal. These are good prospects for developing sustainable data stores.

As the saying goes, nothing lasts forever. The laws of physics confirm it: on our planet, all the processes increase the entropy, thus the molecular disorder. For example, a broken glass would never go up.

Theoretical physicists at the Technical University of Munich (TUM) and the Max Planck Institute for Complex Systems Physics have discovered that anything that seems inconceivable in the everyday world is possible at the microscopic level.

"Until now, the hypothesis was that the quasiparticles of interacting quantum systems disintegrate after a while.We now know that it is the opposite." that occurs: strong interactions can even completely stop the disintegration, "says Frank Pollmann, professor of theoretical physics in the solid state in the solid state. the TUM. The collective vibrations of the network in crystals, called phonons, are an example of such quasi-particles.

The concept of quasiparticles was invented by physicist and Nobel Prize winner Davidovich Landau. He used it to describe the collective states of many particles or rather their interactions due to electric or magnetic forces. Because of this interaction, several particles act as one.

Numerical methods open up new perspectives

Until now, it was not known in detail which processes influenced the fate of these quasiparticles in interacting systems, "says Pollmann.It is only now that we possess numerical methods with which we can calculate complex interactions as well as computers with sufficiently high performance to solve these equations ".

"The result of the elaborate simulation: Certainly, quasiparticles break down even though new entities of identical particles emerge from debris," said lead author Ruben Verresen. "If this degradation occurs very quickly, an opposite reaction will occur after a while and the debris will converge again.This process can reproduce itself at infinity and a sustained oscillation between decomposition and rebirth occurs . "

From a physical point of view, this oscillation is a wave transformed into matter, which, according to the quantum wave-particle duality, is possible. Therefore, quasi-immortal particles do not transgress the second law of thermodynamics. Their entropy remains constant, the decomposition has been stopped.

Reality

The discovery also explains phenomena that were confusing up to now. Experimental physicists had measured that the magnetic compound Ba3CoSB2O9 was surprisingly stable. Magnetic quasi-particles, magnons, are responsible for them. Other quasi-particles, rotons, ensure that helium, which is a gas on the Earth's surface, becomes a liquid at absolute zero, which can flow unrestricted.

"Our work is basic research," says Pollmann. However, it is quite possible that one day the results even allow applications, for example the construction of durable data memories for future quantum computers.