Physicists may have found the missing link for quantum computers
Many physicists are searching for a triplet superconductor. Indeed, we could all do with one, although we may not know it yet – or understand why.
‘Triplet superconductors’ are the key to achieving the most energy-efficient technology in the future.
“A triplet superconductor is high on the wish list of many physicists working in the field of solid state physics,” said Professor Jacob Linder.
He works at NTNU’s Department of Physics, more specifically at QuSpin – a research centre where physicists grapple with some of the gnarliest questions you can imagine.
“Materials that are triplet superconductors are a kind of ‘holy grail’ in quantum technology, and more specifically quantum computing,” explained Linder.
He and his colleagues are now on the trail of this triplet superconductor – much to the excitement of physicists worldwide.
“We think we may have observed a triplet superconductor,” said Professor Linder.
This is massive news, as we will attempt to explain below.
“One of the major challenges in quantum technology is being able to perform data operations with sufficiently high accuracy,” says Jacob Linder. Photo: Per Henning, NTNU
Making unstable technology stable
Linder’s work involves quantum materials science and how it can be used in spintronics and quantum technology. More detailed information about this field of study can be found in the fact box below.
Spin and spintronics
- Spin is a property of several elementary particles—for example, the particles that atoms are made of. Electrons and photons can have spin.
- This type of spin is the reason why some materials are magnetic.
- Spintronics is an alternative technology to electronics, where we can use spin instead of electric charge to transmit signals.
The short version is that spin is a property of electrons that we can use to transmit information in ways different from those currently used in conventional computers. Spin can also be used in quantum technology, especially when combined with superconductors, but the current technology is frustratingly unstable.
“One of the major challenges in quantum technology today is finding a way to perform computer operations with sufficient accuracy,” explained Linder.
And that is where a triplet superconductor comes in.
In collaboration with colleagues in Italy, who conducted experiments, Linder has published an article in the renowned journal Physical Review Letters. The editors chose the paper as one of their weekly recommendations.
“Triplet superconductors make a number of unusual physical phenomena possible. These phenomena have important applications in quantum technology and spintronics,” said Linder.
More detailed information about these applications can be found in the fact box below.
The frustratingly difficult fact box below
- The reason triplet superconductors can transfer spin without energy loss is that the superconducting particles now carry spin with them.
- Triplet superconductors can also be used to create a very exotic type of particle called a "Majorana particle".
- A Majorana particle is its own antiparticle. Therefore, it can perform calculations in a quantum computer in a stable way. Don’t ask us why.
Superconductors versus triplet superconductors
Conventional superconductors can transfer electricity (electrons) without measurable electrical resistance. They can be very useful, but are not always efficient enough.
- Conventional superconductors are so-called ‘singlet superconductors’. In simple terms, this means that the superconducting particles do not have spin.
- In triplet superconductors, however, the superconducting particles have spin.
So, what does this mean?
By placing a superconductor (S) between two ferromagnets (F), superconductivity will be affected by the magnetization (large black arrows). A triplet superconductor is affected differently than a conventional superconductor. Illustration: QuSpin/NTNU
“The fact that triplet superconductors have spin has an important consequence. We can now transport not only electrical currents but also spin currents with absolutely zero resistance,” explained Linder.
This means that extremely fast computers can be operated using almost no electricity at all!
If physicists discover a triplet superconductor, it will be possible to transmit information using spin without losing any energy.
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NbRe is promising for triplet superconductors
“In our published article, we demonstrate that the material NbRe exhibits properties consistent with triplet superconductivity,” said Linder.
NbRe is a niobium–rhenium alloy, and both metals are rare. (See the fact box.)
NbRh
- Niobium is a fairly rare metal, but not impossible to obtain. It has been extracted in Norway.
- Rhenium is much rarer still—and expensive, too.
“It is still too early to conclude once and for all whether the material is a triplet superconductor. Among other things, the finding must be verified by other experimental groups. It is also necessary to carry out further triplet superconductivity tests,” explained Linder.
He is, however, hopeful.
“Our experimental research demonstrates that the material behaves completely differently from what we would expect for a conventional singlet superconductor,” added Linder.
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Works at relatively high temperatures
“Another advantage of this material is that it superconducts at a relatively high temperature,” said Linder, although it should be noted that his perspective on what is a ‘high temperature’ is a little different than how we think of ti.
In this context, ‘high temperature’ means 7 Kelvin (K), which is just above absolute zero at -273.15 degrees Celsius. So, yes, it’s all relative. Other possible candidates for triplet superconductivity require temperatures of around 1K, making 7K seem almost tropical and certainly very achievable.
The NTNU research thus looks very promising.
Reference:
Colangelo, F., Modestino, M., Avitabile, F., Galluzzi, A., Makhdoumi Kakhaki, Z., Kumar, A., Linder, J., Polichetti, M., Attanasio, C., & Cirillo, C. Unveiling Intrinsic Triplet Superconductivity in Noncentrosymmetric NbRe through Inverse Spin-Valve Effects. Phys. Rev. Lett. 135, 226002 – Published 25 November 2025. DOI: https://doi.org/10.1103/q1nb-cvh6
