In most versions of the double-slit experiment, including those conducted with light, the setup is typically done in a controlled environment, which often includes a vacuum or a low-pressure gas environment. This is done to minimize interactions with air particles or other external influences that could potentially disturb the interference pattern or cause the wave function to collapse.
When particles, such as photons, interact with other particles or their surrounding environment, it can lead to a process called decoherence. Decoherence refers to the loss of quantum coherence and the entanglement between particles and their environment. Interaction with air particles, for example, can cause random collisions and exchanges of energy, momentum, or information, which can disrupt the delicate interference patterns observed in the double-slit experiment.
By conducting the experiment in a vacuum or low-pressure environment, the number of interactions and the potential for decoherence is significantly reduced. This allows for a clearer observation of the wave-like interference patterns and helps to preserve the delicate quantum coherence of the system.
It's important to note that even in a vacuum, certain experiments may still involve interactions or measurements that can collapse the wave function. The act of observation or measurement, regardless of the environment, can disturb the system and alter the behavior of the particles. Therefore, experimental setups are carefully designed to minimize such disturbances and extract meaningful information about the wave-particle duality of the particles under investigation.