Discovering new phases of matter and classifying such phases are among the most important goals in physics. In a new study, Dr Tie-Cheng Guo and Professor Li You at Tsinghua University in Beijing present a new methodology to discover new quantum phases of matter, using the concept of ‘time order’. Through identifying and defining quantum phases from this perspective, time order could become a new paradigm in physics, helping researchers to gain more insight into quantum many-body systems.

The Hilbert space formulation is a central idea in quantum theory, but the ideas used by physicists to interpret the formulation widely differ. Furthermore, concepts in quantum mechanics are very abstract to those outside the field. Professor Inge Helland from the University of Oslo approaches these problems through what he calls ‘conceptual variables’, which belong to the minds of one or more conscious observers. From this basis, he achieves a new derivation of the Hilbert space formulation, which he hopes will lead to more satisfying studies of the foundations of quantum theory.

By stacking layers of atom-thick materials on top of each other, researchers are opening up a whole host of exciting new possibilities for technology and scientific research. Particularly interesting properties in these 2D materials could be achieved by stacking three or more of these layers – but so far, the large-scale production of these structures has proven difficult. Using carefully applied techniques, Dr Jakub Sitek and his team at Warsaw University of Technology have made important steps towards overcoming this challenge.

Interactions between positive and negative ions are important processes in nature. However, there is a lack of experimental facilities designed to study them in detail. This picture could now be changing thanks to DESIREE: a facility where different ion beams can be stored and cooled for extensive periods within separate rings, before colliding with each other. Run by an extensive team of physicists at Stockholm University, the instrument is shedding new light on how ions interact in a wide range of environments – from dynamic stellar atmospheres, to interstellar space.