Quantum tunneling is a phenomenon in quantum mechanics where a particle has a non-zero probability of crossing an energy barrier even when it does not possess enough energy to overcome the barrier classically. While it is theoretically possible for a single atom to tunnel through a thin sheet, the likelihood of observing such an event in a laboratory setting is extremely low.
Experimental verification of quantum tunneling typically involves ensembles of particles rather than individual atoms. The probabilities involved in quantum tunneling are statistical in nature and are described by wave functions. Thus, it is difficult to observe a single atom tunneling through a barrier due to the probabilistic nature of quantum mechanics.
That being said, there have been experiments where the phenomenon of quantum tunneling has been observed for particles on the atomic scale. For example, scanning tunneling microscopy (STM) is a technique that relies on the quantum tunneling of electrons to image the surfaces of materials at the atomic scale. However, STM operates by measuring the tunneling current between a sharp tip and a sample surface, rather than launching or firing individual atoms through a thin sheet.
In summary, while the theoretical possibility of a single atom tunneling through a thin sheet exists, it is highly improbable to observe such an event in a controlled laboratory setting. Quantum tunneling is better understood and observed statistically, using ensembles of particles or in techniques like scanning tunneling microscopy.