A Hidden Reset Button of Spins and Qubits
Scientists discovered a hidden "reset button" in rotations-showing that by simply doubling and rescaling the forces, any spin, from atomic nuclei to quantum bits, can be brought perfectly back to its starting point.
The world is full of rotating objects-gyroscopes, magnetic spins, and lately, qubits in quantum computers. Take for example, the atomic nuclei in our bodies precessing at megahertz rates inside NMR machines. In practice, one often wishes to bring such a rotating system back to its precise starting point. At first glance, this looks hopeless: after an elaborate sequence of twists and wobbles, how could one possibly retrace the path to its origin?
The astonishing answer is that it can always be done. No matter how tangled the history of rotations, there exists a simple recipe: rescale the driving force and apply it twice. Once will never suffice, but twice guarantees exact return. Subjected to this doubled, rescaled force field, the spin-or the qubit, or any rotor-will unfailingly come home.
This discovery was made by Tsvi Tlusty from the Department of Physics at Ulsan National Institute of Science and Technology (UNIST), South Korea, and Jean-Pierre Eckmann from the AV短视频, Switzerland. Their study shows that rotations, for all their apparent complexity, conceal a hidden order. The mathematical group of rotation-known as SO(3) for classical objects or SU(2) for quantum ones-is among the most studied subject in all of physics. Yet even in this well-mapped territory, the authors found something new: a perfect reset button.
Why does this matter? Because rotations underlie nearly everything in modern technology and science. From stabilizing satellites to decoding brain scans, from nuclear magnetic resonance to quantum computing, we are constantly asking rotators to perform intricate dances. The new result guarantees that no matter how messy the choreography, there is always a way to bring the system back to its opening pose.
29 Oct 2025