In quantum mechanics, there is no direct analog to an "atom" for time. The concept of an atom is associated with the structure of matter, specifically the arrangement of protons, neutrons, and electrons within an atom. However, time is considered a fundamental quantity in physics, and it does not have a structure or constituents like atoms.
In the framework of quantum mechanics, time is treated as a parameter that governs the evolution of quantum systems. The dynamics of quantum systems are described by mathematical equations, such as the Schrödinger equation or the time-dependent Schrödinger equation, which determine how the wave function of a system changes over time.
In certain areas of physics, such as quantum field theory, which combines quantum mechanics with special relativity, time is treated as an operator within the mathematical formalism. However, this does not imply that time is composed of smaller components like an atom. It is simply a mathematical representation within the theory.
In summary, while the concept of an "atom" has a clear counterpart in the quantum realm for matter, there is no direct equivalent for time. Time is a fundamental parameter in physics, and its quantum behavior is described by mathematical equations rather than a discrete structure.