The use of a series of gratings in the double-slit experiment with molecules does not actually minimize the effects of decoherence. Instead, it can increase the effects of decoherence and make it more challenging to observe interference patterns.
Decoherence is the process by which a quantum system interacts with its environment, causing the system to lose its quantum coherence and behave more classically. The environment can consist of various factors, such as air molecules, vibrations, or electromagnetic radiation, that interact with the quantum system and lead to the entanglement of the system with the environment.
In the case of the double-slit experiment with molecules, the series of gratings are typically placed after the slits and act as a means to detect the particles or measure their positions. These additional interactions with the gratings and subsequent detection can introduce decoherence effects.
When a molecule passes through the series of gratings, it undergoes interactions with the grating structure, which can lead to the entanglement of the molecule with the grating and its environment. This entanglement causes the wave function of the molecule to collapse, effectively destroying the interference pattern that would have been observed on the screen.
In contrast, when the double-slit experiment is conducted without the series of gratings, and the molecules are detected using other means (e.g., by ionizing them and observing the resulting ions), the decoherence effects can be minimized. This is because the detection process is less likely to cause significant interactions and entanglement with the environment, preserving the coherence of the molecule's wave function and allowing the interference pattern to be observed.
So, while the series of gratings in the double-slit experiment with molecules can provide a means of detection, they also introduce additional interactions and can increase the effects of decoherence, making it more difficult to observe interference patterns. Minimizing decoherence is typically achieved by using detection methods that have minimal disturbance to the quantum system.