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Dutch researchers have achieved the ‘impossible’.
By creating a new type of superconductor, they potentially unlocked technology that could make computers hundreds of times faster – a breakthrough potentially on the scale of the first electronic revolution.
“It will influence all sorts of societal and technological applications,” predicts researcher Mazhar Ali from the Delft University of Technology (TU Delft). “If the 20th century was the century of semiconductors, the 21st can become the century of superconductors.
Outside the nucleus of an atom are negatively charged particles called electrons, which can move from one atom to another – this movement is electricity.
In some materials the electrons are tightly bound to the nucleus and do not flow easily – these materials are insulators. In others, like copper and silver, the electrons are loosely bound and can easily move from atom to atom – they are conductors.
Semiconductors are materials that sit between conductors and insulators – silicon is a commonly used semiconductor.
“If the 20th century was the century of semiconductors, the 21st can become the century of superconductors.
We rely on conductors and semiconductors to carry electricity – we use copper wires to send it from power stations to our homes, for example, and silicon chips to control its movement inside our electronic devices.
All conductors and semiconductors are at least somewhat resistant to the flow of electrons. This means that each time an electron moves from one atom to another, some energy is lost in the form of heat.
These little chunks of wasted energy add up: about 5% of the electricity produced in US power plants never reaches homes. Meanwhile, in our devices, overheating limits the operating speed of processors and can cause programs to crash.
In 1911, a Dutch physicist discovered that, under the right circumstances, some materials do not lose any energy when their electrons move from one atom to another. These are called superconductors, and an example is aluminum when cooled to -271 degrees Celsius (-457 degrees Fahrenheit).
If we could replace conductors or semiconductors with superconductors, our electronic devices could become hundreds of times faster, without wasting energy overheating, and we could save billions of dollars in electricity transmission losses. every year.
However, a major problem is that electricity flows without resistance in both directions through a superconductor.
For most applications, we need to be able to move a current in one direction, from point A to point B – in the 1970s, IBM researchers determined that we could never use superconductors in computers, for example, unless someone finds one. -way superconductivity.
It is possible to guide a current through a superconductor using a magnetic field, but these are difficult to control at the nanoscale. This has considerably limited applications for superconductors – today they are mostly reserved for things like MRI machines and maglev trains.
Researchers at TU Delft have now done what seemed impossible, flowing electricity through a superconductor in one direction without the use of magnets. They call it a “Josephson diode”.
The key design used a 2D layer of a material – meaning it’s only one atom thick – that has an electromagnetic field built into it. This material (called Nb3Br8) was then sandwiched between 2D layers of a superconductor (called NbSe2).
“Technology that was previously only possible with semiconductors can now potentially be achieved with superconductors.”
When an electric current is applied to this sandwich, the electrons encounter no resistance as they flow in one direction – but in the opposite direction they encounter much more resistance – about as much as a normal conductor.
The researchers don’t yet know how their diode works – “People have a rough idea, but a rigorous theory doesn’t exist yet,” Ali told New Scientist – but they think their discovery could have huge implications.
“Technology that was previously only possible with semiconductors can now potentially be achieved with superconductors using this building block,” Ali said. “That includes faster computers, like in computers with up to terahertz speed, which is 300 to 400 times faster than the computers we’re using now.”
The next steps
A unidirectional magnetless superconductor is a major breakthrough, but the TU Delft team still has hurdles to overcome before its discovery can be useful outside the lab.
One is temperature – the Josephson diode must currently operate at -271°C (-455.8°F), which would not be practical for most applications.
The plan now is to experiment with superconducting materials known to operate at higher temperatures – if the diode can operate at -196°C (-321°F) or higher, cooling could be handled by liquid nitrogen, which is already used to manage heat in data centers.
Another hurdle is figuring out how to increase production.
“While it’s great that we’ve proven this works in nanodevices, we’ve only made a handful,” Ali said. “The next step will be to study how to scale production to millions of Josephson diodes on a chip.”
We won’t be able to keep the chips in our phones and laptops hundreds of degrees below zero any time soon. But if the TU Delft team can overcome these remaining challenges, Ali sees the diodes being used in places where advanced cooling systems are already installed, such as supercomputer facilities.
They could also be used in server farms, and with more and more cloud computing, it’s possible that one day everyone will be able to harness the power of superconducting computers on the Internet.
“Existing infrastructure could be adapted at little cost to work with Josephson diode-based electronics,” Ali said. “There is a very real chance, if the challenges discussed…are overcome, that it will revolutionize centralized computing and supercomputing!”
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