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 […]
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A speed limit also applies in the quantum world
Science Daily February 19, 2021 In two-level systems, the quantum brachistochrone solutions are long known but they are not applicable to larger systems, especially when the target state cannot be reached through a local transformation. An international team of researchers (Germany, USA – MIT, Italy) has demonstrated fast coherent transport of an atomic wave packet over 15 times its size, a case of quantum processes going beyond the two-level system. The measurements of the transport fidelity revealed the existence of a minimum duration—a quantum speed limit—for the coherent splitting and recombination of matter waves. They obtained physical insight into this […]