Quantum tunneling is a phenomenon where a particle can pass through a potential energy barrier despite not having enough energy to overcome it classically. It is a fundamental aspect of quantum mechanics and has been observed in various experiments. However, quantum tunneling is typically observed at the microscopic or atomic scale rather than at the macroscopic level.
To date, the largest objects that have been experimentally confirmed to exhibit quantum tunneling are certain complex molecules, such as fullerene molecules (C60) and even larger carbon-based molecules. For example, in 1999, researchers at the University of Vienna demonstrated quantum tunneling of a fullerene molecule through a double barrier.
In recent years, there have been advances in observing quantum phenomena at larger scales. One notable example is the observation of quantum behavior in tiny mechanical devices called nanomechanical resonators. These devices consist of tiny vibrating structures, such as nanowires or nanotubes, and they have been observed to exhibit quantum behavior, including quantum tunneling.
However, it's important to note that the scale at which quantum phenomena can be observed is still limited, and larger macroscopic objects, such as everyday objects or living organisms, have not been experimentally confirmed to exhibit quantum tunneling. The boundary between classical and quantum behavior is an active area of research, and there is ongoing exploration to understand the limits of quantum effects in larger systems.