Quantum physicists control supercurrent

August 10, 2006

Netherlands scientists say they've shown that in a quantum-mechanical circuit, the current can be reversed by using a single electron.

The researchers led by Leo Kouwenhoven from the Delft University of Technology created a superconducting quantum interference device, or SQUID, and discovered they could reverse the current by placing an electron on a "weak link" where the current has to jump across a kind of barrier.

In the SQUID made by Kouwenhoven's team the current circulates around a ring-shaped circuit made from microscopic aluminum wire. There are two breaks in the loop, each bridged by wires just 60 nanometres wide and made from the semiconductor indium arsenide. At very low temperatures the aluminum becomes superconducting and the current is carried by pairs of electrons with zero electrical resistance.

The team used electric fields to turn the semiconductor nanowires into "quantum dots" -- isolated islands of electrical charge. Electron pairs can jump to and from the islands, so the supercurrent becomes chopped into discrete parcels of two electrons.

By adding just one electron to the quantum dot the researchers found they could reverse the direction of the supercurrent.

The physics are explained in the journal Nature.

Copyright 2006 by United Press International

Explore further: Shift from electronics to spintronics opens up possibilities of faster data

Related Stories

Seeing quantum motion

August 28, 2015

Consider the pendulum of a grandfather clock. If you forget to wind it, you will eventually find the pendulum at rest, unmoving. However, this simple observation is only valid at the level of classical physics—the laws ...

Recommended for you

Long-sought chiral anomaly detected in crystalline material

September 3, 2015

A study by Princeton researchers presents evidence for a long-sought phenomenon—first theorized in the 1960s and predicted to be found in crystals in 1983—called the "chiral anomaly" in a metallic compound of sodium and ...

Probing the limits of wind power generation

September 2, 2015

(Phys.org)—Wind turbine farms now account for an estimated 3.3 percent of electricity generation in the United States, and 2.9 percent of electricity generated globally. The wind turbine industry is growing along all vectors, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.