November 28, 2022

Scientists force electrons to break Ohm’s Law

Scientists in the Quantum Dynamics Unit at Okinawa Institute of Science and Technology Graduate University (OIST) are running experiments to see how the motion of electrons is impacted by fluid.

Ohm’s law, a physics law, states that electric current is proportional to voltage and inversely proportional to resistance, so if the resistance equally distributes between two channels, half the electrons will go down each channel. But if the electrons are sitting on liquid, rather than in a solid, they might break Ohm’s law.

This theory comes from the concept of a polaron, which is an electron that’s “dressed” by a cloud of the medium it’s sitting in. This makes it heavier, slower and changes its behavior. Previously polarons have been discussed in terms of ionic crystals in solids, but much more rarely in liquids.

The researchers used superfluid helium, which has several unique properties. For example, it remains in a liquid form at temperatures down to absolute zero, when any other liquid would freeze, and behaves like fluid with zero viscosity, or no resistance. Electrons would only be able to sit on top, rather than sinking. Thus, it provided the researchers with a 2D electron system.

They created a tiny structure, on the scale of micrometers, of three reservoirs connected by a T-junction, and slightly submerged this structure in superfluid helium.

As the electrons moved and disturbed the liquid, they created capillary waves, or ripples. At high electron densities, the electrons became trapped in the shallow dimple of the waves. These are slightly different from the traditional polarons, so the researchers called them ripplopolarons, inspired by their similarities to ripples on water.

The researchers applied an electric field, which moved the ripplopolarons out of the left reservoir. As they moved along the channel, they came to the junction, and could either turn and go to the side reservoir or continue straight to the right reservoir. The ripplopolarons continued straight from the left reservoir to the right reservoir, following momentum conservation rather than Ohm’s law.

Electrons in fluids could be useful when it comes to building qubits. If electrons in fluids are used for qubits, that could create a flexible, moveable architecture for the computers. (SciTechDaily)

This study was published in Physical Review Letters.

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