Now you see it: Real-space observation of many-body proton tunneling in water nanocluster
There's more to quantum tunneling than meets the eye – or rather, the visualization technique. Most quantum tunneling discussion focus on incoherent single-particle tunneling; on the other hand, quantum tunneling in the context of proton dynamics usually involves many hydrogen bonds at once, which leads to what is known as correlated many-body tunneling. (The many-body problem refers to the properties of microscopic systems that are described by quantum mechanics, comprising a large number of interacting particles – that is, ≥ 3 – which can become entangled.) The downside is that while single-particle tunneling is well understood, many-body tunneling is still shrouded in mystery. Recently, however, scientists at Peking University, Beijing reported the real-space observation of concerted proton tunneling in a cyclic water tetramer – a macromolecular nanocluster consisting of four water molecules arranged in a loop or ring – by using a cryogenic scanning tunneling microscope (STM). The scientists found...