University of Zagreb physicists confirm quantum state predictions

Physicists Ivan Jakovac and Mihael Grbić from the University of Zagreb’s Faculty of Science led an international team that has experimentally confirmed theoretical predictions regarding two quantum phases in magnetic material. The research, published on the cover of Physical Review Letters, focuses on Haldane chains—insulating junctions composed of chains of tiny magnets first theorized by Duncan Haldane in 1983.

The study demonstrates that when these chains are exposed to strong magnetic fields and extremely low temperatures, they exhibit quantum criticality, behaving as one-dimensional conductors where magnetic quasi-particles move without resistance. Upon further cooling, the system transitions into a Bose-Einstein condensate, the fifth state of matter.

These findings provide direct experimental validation for theories regarding magnetic Bose-Einstein condensates proposed in 1990 and Tomonaga-Luttinger liquids predicted in the early 2000s. The researchers achieved this by varying magnetic fields across a wide range from 0 to 34 T to observe the system's evolution in accordance with quantum laws.