“Why are People So Hyped about Quantum Computers? – Q&A”

How far have quantum technologies come? And what do we really mean when we use the word quantum? Senior Chancellor Ulrich Busch-Hoff has been researching and communicating quantum physics for several years. Here he provides an overview of a rapidly developing field.

What is quantum technology?

It is the field of technologies in which quantum physics is actively used. These are techniques that can only be achieved using quantum physical phenomena. Usually these are phenomena such as superposition, where an object, such as an atom, can assume more than one value or be in more than one place at the same time, and entanglement, where an object, such as an atom, is physically separated from another atom, but when They are connected together so that the effect of one atom affects the other as well.

Quantum physics is over 100 years old, so what’s new?

The ideas are already old – from the time of Niels Bohr and Einstein – but we have now reached a stage where theories have been presented and we can begin to exploit them in practice. We can do this because today we can control quantum physical systems such as atoms, electrons or photons in a way that can be used in technological solutions such as cryptography, sensors and computers – although most of them are still only possible in laboratories.

What is the most mature quantum technology?

We are very advanced in encoders and sensors. Last year, DTU participated in several demonstration experiments of quantum-encoded data being transmitted between two geographic locations.

In quantum sensors, there are actually many different types that can measure physical quantities with extreme precision. Some can measure small differences in the gravitational field. This could be used, for example, in construction work to map the subsoil before construction, or to predict earthquakes. Other sensors measure magnetic fields from, for example, muscle activity and nerve pathways and have great potential in areas such as medical diagnostics. Magnetic field sensors can also be used for military purposes such as navigation.

The quantum computer is perhaps the most immature of all technologies.

Why is there so much hype around a quantum computer?

there are many reasons. What started the hype, and is still driving it in some way, is an algorithm for quantum computers developed by Peter Shor, an American mathematician and professor at MIT, in 1994. Shor’s algorithm makes it possible for a powerful quantum computer to break RSA encryption. This is the encryption that is widely used when we send data on the Internet.

But there is also an obvious assumption that quantum computers will eventually be able to handle many other computational operations that would be impossible with a regular computer. Therefore, a huge market potential for quantum computers is expected. In other words, there is a lot of money to be made for those who can realize a quantum computer.

The noise is also partly due to the difficulty of developing a quantum computer and its exploitation of quantum phenomena that many do not understand. A fascination with the technology itself contributes to the hype.

When will we have quantum computers?

We’re still a long way from having a fully developed quantum computer. It is still not clear which physical system will make up the quantum mechanically usable qubits inside a quantum computer. Some test for photons, other atoms, or ions – yet others test electrons in a superconducting material. In some places, mechanical oscillations are used. Research and development is being done on all of these platforms around the world.

Calculations show that it takes a quantum computer from 10 to 20 million qubits to break the RSA cipher. Currently, the largest quantum computer is in the region of 430 quantum bits. So there is still a way to go. So, at the risk of becoming a laughing stock for future generations, I think it will be another 20 years before we have a quantum computer that meets these expectations.

Will I have a quantum computer at home?

I’ll answer this based on where the technology is today and what we think a quantum computer will do well – and with that in mind – I think quantum computers are not going to be something we’re going to have at home. It will be for very specific and large-scale calculations. It will not be a computer that we can use to go to Facebook or watch YouTube videos.

I think a quantum computer will have a role as HPC (High Performance Computing), which you can buy access to today if you need to do computations on a large scale. But I could be completely wrong. Technology often evolves very differently than we expect, so we may all be walking around with a quantum computer in our pocket in 30 years.

Do you need to be interested in quantum physics as a non-physicist?

Quantum phenomena such as superposition and entanglement are a very fascinating part of nature that can cause amazement and inspire completely new ideas in us humans. Instead of racing through the world with blinkers, it makes us pause and acknowledge that there is much more to nature than immediately meets the eye. It’s like heaven. We can be indifferent to black holes and “dark matter”, but I think it has to do with fascination, general education and awareness of what nature actually contains.

At present, we do not encounter applications of quantum technology in our daily lives. This means that when we talk about it, we have to talk about quantum phenomena. They challenge us, because we have no experience, for example, of superimposition in our visual world, which is governed by conventional physics, where things like a chair can only exist in one place in a room.

But I think that when we start using quantum technology, we will stop focusing on fundamental quantum phenomena. This is actually the case with other technologies such as computers and mobile phones. Most of us don’t think about how it works. But we know how to use it.