Month: November 2025

For many years, since the beginning of the 19th century, the existence of magnetism in low dimensions has been both desired and controversial. It was long thought, that magnetic orders in low dimensional systems could not be realized at temperatures different from zero. At least, this was what the Mermin-Wagner theorem stated for isolated Heisenberg spins. The scarcity of low-dimensional materials with magnetic properties, and the partial understanding of the role of spin-anisotropy have supported this picture for several decades. In three-dimensions, magnetism has revolutionized our everyday life, enabling familiar technologies which are of common use. A few examples include computers’ memories, RAM, hard-disks, key cards, credit cards, electric batteries, light, and distance sensors. This relentless pace of development has motivated the search for magnetism in systems with increasingly smaller sizes.

With cooperation of experimental and theoretical physics, researchers discovered that spin-anisotropy can stabilize low-dimensional magnetism. In this, spin-orbit coupling plays an important role. Surface experimental probes, such as angle-resolved photoelectron spectroscopy provide researchers access to the electronic structure of solids. Despite the advances in the field, recently, new forms of surface local magnetism completely different from standard descriptions have appeared, with relevance in quantum transport information, dissipationless transport, and quantum sensing.

Here, I aim to give an overview of a new powerful methodology to uncover hidden phases of electrons, including spins, and magnetism which was so fare elusive, and that we were able to uncover for the first time.

Finding the time dependent perturbation that extracts the maximal amount of energy (a.k.a. ergotropy) from a thermally isolated quantum system is a central, solved, problem in quantum thermodynamics. Notably, the same problem has been long studied for classical systems as well, e.g., in the field of plasma physics, but a general solution is still missing there. By building on the analogy with the quantum solution, we provide the classical ergotropy extraction driving: it consists of an instantaneous quench followed by an adiabatic return. The solution is valid under the ergodic hypothesis and we also show that for quantum systems that are classically ergodic the classical expression of ergotropy emerges as the semiclassical limit of the quantum one. The presented results open new ways for practical energy recovery in the classical regime and for understanding the genuine quantum features of quantum ergotropy.

We will review the research areas currently developed at the Quantum Communication Group in Malta, with the aim of generating collaboration between the groups. Particular emphasis would be placed on novel security proof techniques and the optimization of quantum-classical channel capacity.