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TIME OUT Electrons can escape their atoms, even if the particles don’t have enough energy to do so, through quantum tunneling. But such tunneling takes time, a new study suggests.
Quantum particles can burrow through barriers that should be impenetrable - but they don't do it instantaneously, a new experiment suggests.
The process, known as quantum tunneling, takes place extremely quickly, making it difficult to confirm whether it takes any time at all.
Now, in a study of electrons escaping from their atoms, scientists have pinpointed how long the particles take to tunnel out: around 100 attoseconds, or 100 billionths of a billionth of a second, researchers report July 14 in
Physical Review Letters.
In quantum tunneling, a particle passes through a barrier despite not having enough energy to cross it. It's as if someone rolled a ball up a hill but didn't give it a hard enough push to reach the top, and yet somehow the ball tunneled through to the other side.
Although scientists knew that particles could tunnel, until now, "it was not really clear how that happens, or what, precisely, the particle does," says physicist Christoph Keitel of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany.
Theoretical physicists have long debated between two possible options. In one model, the particle appears immediately on the other side of the barrier, with no initial momentum. In the other, the particle takes time to pass through, and it exits the tunnel with some momentum already built up.
Comment: Bruce Luyendyk, a professor of marine geophysics at UC-Santa Barbara, first proposed the concept of Zealandia in 1995.