Researchers discover new fundamental quantum mechanical property

Jan 8, 2016

A newly-discovered fundamental property of electrical currents in extremely small metal circuits demonstrates how negatively-charged particles can wash over said circuit like waves, generating interference in parts of the circuit where no current is delivered.

This characteristic, discovered by researchers at the University of Twente’s MESA+ institute and detailed in a recent Scientific Reports paper, is due largely to the circuit’s geometry as well as the quantum mechanical wave character of electrons, according to the study authors.

As part of their research, the MESA+ team demonstrated electron interference—a phenomenon in which propagating waves interact coherently—in a gold ring with a 500 nanometer diameter. One side of the ring was connected to a tiny wire through which an electrical current could be driven, while the other side was connected to a different wire attached to a voltmeter.
When they applied the current, sending a varying magnetic field through the ring, they detected electron interference on the other side of the ring, even though no net current passed through the ring. Their experiment revealed that electrons can bleed into the ring, thus altering the electrical properties in parts of circuit not expected to be affected by the current.

Findings could help shape future quantum computers

Despite the fact that the gold ring was diffusive (its electron mean free path was much smaller than the ring itself), the authors said that the effect was surprisingly pronounced. It shows that electrons must be considered waves in nanoscale circuits at extremely low temperatures, since this behavior is said to be a prime example of quantum mechanical wave-particle duality.

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3 comments on “Researchers discover new fundamental quantum mechanical property

  • Not sure I understand the actual setup of the experiment. How did the single wire attach to the ring? There must have been a complete circuit for the current to pass through. A diagram would be good to see.
    The best I can envisage is a wire with current passing through it and then the ring touches onto the side of the wire. Really that could be looked upon as two wires.
    The whole outcome makes perfect sense if you veiw the electrons as particles and see their movement as a kind of transverse wave. Almost like the electrons in the ring are being jiggled by the ones passing by in the wire. Not sure that’s a good analogy.
    I wonder how long it will be before this effect will find some practical use, it sounds like it must have some.
    The article says it happens at low temperature so would be a limiting factor perhaps? Is that becase at higher temperatures the natural random particle/wave movement swamps the measurable effect? But if so is the effect still there? Like superposition?

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  • This has no implications for conventional circuits (now heading below 10nm) processing bits of information. It does though have possible threats and opportunities in the processing of qubits.

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