Superconductors: The toys for Rocket Boys in 2023. Or more!

Are we barking up the wrong tree when we try to find materials that can superconduct at room temperatures? Would it change our computers, our ambitions for levitation and our path on quantum computing?

The search for the ultimate superconducting material is as elusive and as exciting as the discussions on Uranium, and Plutonium, that kept physicists and scientists busy almost half a century back. Why does this race matter? And how will it help the IT industry? Who better than a veteran from the Homi Bhabha National Institute for a quick explainer? Indian scientist Dr. G. Ravi Kumar, a Distinguished Professor at GITAM (Deemed to be University) has been a Senior Professor & Associate Dean (Physics) at the Homi Bhabha National Institute and a visiting scientist at science institutes in Germany and USA. Over all these years, he has contributed to some path-breaking research in Electromagnetic Theory, Statistical Physics, Superconductivity and Magnetism, design and fabrication of superconducting magnets and low-temperature equipment.

As researchers at the University of Rochester make a recent claim on the discovery of a room-temperature superconductor with the use of lutetium, we take this chance to chat with subject-expert Dr. G Ravi Kumar on the implications of such experiments. This space is interesting because in 2020 a paper had described a promising superconducting material and it was retracted after its data and details about use of the nonstandard procedure were questioned by some scientists. The retraction in Nature journal in 2020 is now followed by a claim again for the Red Matter – termed so because the material changes from blue to a red hue as it morphs under pressure. This makes us wonder—why these experiments? And what does it all mean. Let’s understand it from a scientist’s lens. Watch out for how he flips the argument—and nudges you to look for another parallel race that can change this race’s outcome.

Why is it important to crack this superconductor at room-temperature?

Superconductors are materials which achieve zero resistance below a temperature called critical temperature. If we can get this to happen at room temperatures, it will save a huge chunk of refrigeration cost. Because today we have Niobium Titanium that can do this but at about 263 Celsius. We also have some materials at 83 to -150 Celsius but they have certain problems. Physicists have been constantly trying to find a room-temperature answer. Incidents like retraction of claims happen not because of wrong intent but, perhaps, due to conditions that can lead someone to think that the material has acquired those qualities.

But would just getting a room temperature material work if the necessity of low pressure still exists?

Ideally, it is great to have something at ambient pressure. So far even for a room-temperature material, a substantial level of pressure would be needed—and that’s not practical.

I am still not aware of any room-temperature superconducting materials at ambient pressure. There are quite a few materials that are superconducting at high pressures.

Why this race?

There’s a pursuit to go higher and higher to get close to room-temperature superconductors. But at the same time, there is another race – cryogenics. That’s where efforts are being made to make it easy to reach lower and lower temperatures in a practical way. Just like a lot of today’s tech industry depends on the knowledge of silicon, there is a lot riding on the superconductivity of materials. Niobium Titanium which is widely used due to good material properties. Currently most MRIs use Niobium Titanium. Niobium Titanium is also the main workhorse in the Large Hadron Collider (LHC) or ITER.

So, if the pressure breakthrough happens first, would the room-temperature work be irrelevant?

It’s not as simple as that.

Why?

Not exactly. Physicists are trying to get fundamental understanding of these areas. That always helps.

Why is cryogenics important to computing?

It affects quantum computing. It all boils down to superconductor junctions. Quantum computers need very low temperatures to function. Commonly, these junctions are made of metallic superconducting materials.

Can these developments affect India’s speed on quantum computers?

The ones from Google and IBM are in the range of thousands of qubits. Keeping a large number of qubits cool needs more cooling power.

Does Meissner effect work in the realm of superconductivity in a strong way? Specially for quantum levitation?

Meissner effect is a fundamental property of a superconductor – apart from zero resistance. In fact, it is more fundamental than zero resistance. But the Meissner effect is not needed for levitation. It is zero resistance which is important for levitation.

Even if we find that magic superconductor, how long is the distance between lab and real-world applications?

Quite large.

What can we do to shrink this gap?

Material properties are important in employing them in applications. For example, Niobium Titanium is malleable and can be easily worked into fine wires. Qubits for quantum computers are normally made of aluminum and niobium, which are superconducting at very low temperatures but can be easily prepared in thin film form and are stable with well-known properties.

Is research on new materials still important?

Research on new materials is always important.

Dr. G. Ravi Kumar

Distinguished Professor, GITAM

By Pratima H

pratimah@cybermedia.co.in