Physicists are increasingly optimistic about the possibility of achieving a quantum state that could remain stable indefinitely, a concept that has intrigued the scientific community for nearly 70 years. This ambitious pursuit, if successful, could fundamentally alter our understanding of matter and pave the way for revolutionary technological advancements, including more powerful quantum computers.
The quest for 'quantum eternity' involves arranging atoms in such a way that the quantum states between them are permanently frozen. This phenomenon, known as many-body localisation (MBL), has long been considered elusive due to the fundamental laws of thermodynamics, which dictate that systems naturally tend towards disorder and thermalisation over time. However, recent experimental findings are providing compelling hints that this seemingly impossible state might be within reach.
The theoretical groundwork for such a possibility was laid in 1958 by physicist Philip Anderson, who proposed that certain disordered arrangements of atoms could trap particles, effectively freezing their quantum state. Anderson’s theory, for which he later shared a Nobel Prize in Physics in 1977, was initially proven in simplified atomic systems. The current challenge lies in demonstrating this effect in more complex, 'real-world' materials where particles actively interact and exchange energy.
Dr. Wojciech De Roeck, a mathematical physicist at KU Leuven in Belgium, highlights the profound implications of achieving MBL. He notes that it would 'open up a whole new class of phases that are otherwise impossible,' suggesting a future where entirely new materials with unprecedented properties could be engineered. The ability to maintain quantum states for extended periods, or even indefinitely, is a critical hurdle in developing robust quantum technologies.
While the concept of chaos and thermalisation is generally considered inescapable in physical systems, MBL systems defy this expectation by not exhibiting such chaotic behaviour. The first significant indication that MBL might be genuinely achievable emerged in 2006, with research by physicists such as Denis Basko at Princeton University, marking a crucial turning point in this long-standing scientific endeavour.