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Old 20-06-2019, 12:35 PM
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"Perfect" quantum "Klein tunnelling" observed for first time

Electron tunnelling, where some electrons can spontaneously
cross to the the other side of an energy barrier even though they
don't have enough energy to climb it, is a seemingly magical
quantum mechanical phenomena long exploited by electronics engineers
when designing some semiconductor devices.

In some devices, quantum tunnelling is an annoyance. In others, it
is a carefully engineered desired attribute.

But in practical devices, not all electrons pass through the barrier, only
a statistically governed number and the remainder are back-scattered.

A phenomena referred to as Klein tunnelling occurs when the barrier
becomes completely transparent allowing particles to cross the barrier
regardless of the barrier's height.

Klein tunnelling was first predicted in 1929.

The Dirac equation attempts to encompass the quantum behaviour of
particles when they are moving at relativistic speeds.

Oscar Klein, a physicist, spotted a counter-intuitive paradox in the
Dirac equation which was that the barrier would become transparent
when its height is larger than the electron energy.

However, Klein tunnelling has never been observed, until today, when
researchers at the University of Maryland have reported it for the first time.

Their discovery was somewhat serendipitous and what's more, they
have observed it with particles moving at non-relativistic speeds.

The work has made the cover of the June 20th 2019 edition of Nature.

It may well have practical applications in electronics and quantum

It certainly is the type of discovery that can win one a Nobel prize.

Story here :-

Paper here (subscription required) :-
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Old 04-07-2019, 08:33 PM
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Nobels all 'round.
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