Niels Gregersen

EU grant for more powerful quantum computers

Thursday 12 Dec 19


Niels Gregersen
Professor, Group Leader
DTU Electro
+45 45 25 37 89

About ERC Consolidator Grants

ERC Consolidator Grants are awarded to outstanding researchers of any nationality and age, with at least seven and up to twelve years of experience after PhD, and a scientific track record showing great promise.

Research must be conducted in a public or private research organization located in one of the EU Member States or Associated Countries.

The funding (maximum of EUR 2 million per grant) is provided for up to five years and mostly covers the employment of researchers and other staff to consolidate the grantees’ teams.

This year, 301 researchers from all over the world have received a total of EUR 600 million in connection with the awarding of ERC’s Consolidator Grants. 

More information.

Associate Professor Niels Gregersen from DTU Fotonik receives one of the coveted ERC Consolidator Grants from The European Research Council (ERC) for the development of a prototype light source for optical quantum computers.

For the next five years, Niels Gregersenv— backed by the grant of approx. DKK 15 million — will work to increase the power of quantum computers in order to, e.g., analyse the molecular composition of new drugs. A challenge that modern computing power is nowhere near being able to cope with.

“Broadly speaking, when you develop new drugs today, you mix together different things without knowing exactly how they work. You assume they work in a certain way, of course, but you have to go through 10-15 years of trial-and-error processes to find out how a patient responds to the drug. And that’s expensive,” says Niels Gregersen and continues:

“If instead you could calculate how each molecule reacts with the cells in the body, for example, you wouldn’t need such a long development process. The problem is that traditional computers — no matter their size — are not suitable for solving such quantum-mechanical calculations, by virtue of their architecture. It would take thousands of years.”

Niels Gregersen’s ambition is to develop an optical quantum computer. Instead of the traditional computers’ bits, the information in a quantum computer is encoded as quantum bits, or ’qubits’. A bit is either 1 or 0, whereas a qubit can be in a so-called ’super position’ and be both 1 and 0 at the same time. In an optical quantum computer, individual photons from a light source carry the information by means of their polarization (the point of direction of their electrical field).

Once you acknowledge that individual photons can carry information, the optical quantum computer’s architecture is easier to understand: A light source transmits photons through some channels. The photons interact in the channels — these interactions are the calculations — and eventually end up at detectors that read the results.

However, large calculations require the individual photons that are emitted to be completely identical and with an identical polarization. Because if you polarize (or encode) nonidentical photons afterwards, errors will occur.  The light source is therefore the hot spot. And that is the key challenge in Niels Gregersen’s ERC project, because there is still no clear theory of how this should be done.

“What we don’t have is a light source that can emit single photons of sufficiently high quality and all pointing in the same direction. I have a plausible theoretical idea of how it can be done, but — and this is something new to me — we must also develop a prototype of such a light source when those five years have passed,” he says and continues:

“The ultimate goal is to make a quantum computer with such good light sources that it will be strong enough to carry out, e.g., the incredibly complex calculations that can be used for developing new drugs. It is not enough that a quantum technology can work with three or five qubits. The technology must be able to scale up to thousands and tens of thousands qubits, otherwise it will never happen."

Niels Gregersen, European Research Council Consolidator Grant-recipient 2019:

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