FockZuständen

FockZuständen, also known as Fock states or number states, are fundamental concepts in quantum mechanics, particularly in quantum field theory and quantum optics. They represent a specific type of quantum state for a system of identical particles. A Fock state is characterized by a definite number of particles in a particular mode or state. For example, a Fock state for photons might describe a system with exactly zero photons, exactly one photon, or exactly two photons, and so on, in a given spatial or energy mode.

The notation commonly used for a Fock state is |n>, where 'n' represents the precise number of particles. This is in contrast to superposition states, where a quantum system can exist in a combination of multiple states simultaneously. In a Fock state, the uncertainty in the number of particles is zero. This property makes Fock states particularly useful for describing phenomena where particle counts are well-defined, such as in laser theory or in experiments involving single-photon sources.

The creation and annihilation operators, fundamental tools in quantum field theory, are directly related to Fock states. The annihilation operator 'a' acting on a Fock state |n> reduces the particle number by one, resulting in a_{n} |n-1>. The creation operator 'a†' acts in the opposite way, increasing the particle number by one, a†_{n} |n+1>. These operators allow for the manipulation and description of systems evolving through Fock states.