In quantum mechanics, the wave function of a particle describes its state and contains all the information about its properties. When a measurement is made on a particle, such as its position or momentum, the wave function "collapses" into a specific value corresponding to the measurement outcome.
The collapse of the wave function is often referred to as wave function collapse or the collapse of the quantum state. It represents the transition from a superposition of possible states to a single definite state. After the collapse, the particle is observed to have a well-defined value for the measured property.
The wave function itself undergoes a change during the collapse. Prior to the measurement, the wave function is typically described by a superposition, which is a combination of various states with different probabilities. For example, a particle's wave function may be a superposition of different position states, indicating that the particle has a certain probability of being found at each position.
However, when a measurement is performed, the wave function collapses to one of the possible states corresponding to the measurement outcome. The specific state after the collapse depends on the measurement result obtained. For instance, if the measurement determines the position of the particle, the wave function collapses to a state representing a single position value.
It is important to note that the precise nature of wave function collapse is still a topic of debate and interpretation within quantum mechanics. Different interpretations, such as the Copenhagen interpretation or many-worlds interpretation, offer different perspectives on how to understand the collapse of the wave function and its implications.
In summary, the wave function of a collapsed particle refers to the specific state that the wave function adopts after a measurement is made, representing a definite value for the measured property.