Margolus–Levitin theorem

The Margolus–Levitin theorem is a result in quantum information theory that establishes a limit on the maximum speed at which information can be processed by a quantum system. Specifically, it provides a bound on the rate at which a quantum system can perform operations or computations. According to the theorem, a quantum system with a given energy E can perform at most 2E/ħ (where ħ is the reduced Planck's constant) operations per unit time.