Science Daily December 22, 2021
Quantum mechanics sets fundamental limits on how fast quantum states can be transformed in time. Two well-known quantum speed limits are the Mandelstam-Tamm and the Margolus-Levitin bounds, which relate the maximum speed of evolution to the system’s energy uncertainty and mean energy, respectively. An international team of researchers (Israel, Germany) tested concurrently both limits in a multilevel system by following the motion of a single atom in an optical trap using fast matter wave interferometry. They found two different regimes: one where the Mandelstam-Tamm limit constrains the evolution at all times. But there was also a second effect: If the energy uncertainty was increased more and more until it exceeded the average energy of the atom, then the minimum time did not decrease further — contrary to what the Mandelstam-Tamm limit would suggest. The researchers thus proved a second speed limit, which was theoretically discovered about 20 years ago. The ultimate speed limit in the quantum world is therefore determined not only by the energy uncertainty, but also by the mean energy…read more. Open Access TECHNICAL ARTICLE
Quantum speed limits in a multilevel quantum system… Credit: SCIENCE ADVANCES, 22 Dec 2021, Vol 7, Issue 52