adiabatisoitumisen

Adiabatisoitumisen, or adiabaticity, refers to a process in thermodynamics and quantum mechanics where a system transitions from one quantum state to another so slowly that it remains in its instantaneous instantaneous eigenstate of the Hamiltonian throughout the process. This means that the system can be described by a sequence of stationary states, where the time-dependent perturbation is minimal. In essence, the system "adapts" to the changing conditions without undergoing transitions to other states.

In thermodynamics, adiabatic processes are those that occur without any heat transfer into or out of the system. While not strictly the same as adiabaticity in quantum mechanics, the concept shares a similar idea of slow change. An adiabatic expansion of a gas, for example, occurs so quickly that there is no time for significant heat exchange with the surroundings. This leads to a decrease in temperature as the internal energy is converted into work.

The adiabatic theorem is a fundamental result in quantum mechanics that states if a system is in an eigenstate of a time-dependent Hamiltonian and the Hamiltonian changes slowly enough, then the system will remain in the corresponding instantaneous eigenstate. The condition for this to hold is that the rate of change of the Hamiltonian must be small compared to the energy differences between the instantaneous eigenstates. This principle has important applications in fields like atomic physics, quantum computing, and condensed matter physics, where understanding how systems respond to slowly varying external influences is crucial.