Transmitting and receiving single photons

Transmitting and detecting single photons. That is possible with the equipment made by Single Quantum. This young company recently received a Valorisation Grant from NanoNextNL to further develop the technology. Possible applications lie in the areas of quantum cryptography and medical imaging.

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photo: Shutterstock

‘During my PhD research at Delft University of Technology, I worked on a sensitive detector for single photons,’ says CEO of Single Quantum Sander Dorenbos. ‘Other research groups showed considerable interest for our detector chips. We initially gave these away in the context of scientific collaboration, but that was not sustainable. We therefore started a company in 2012 to build and sell detector systems. There are currently about fifteen systems being used in different research institutions worldwide, and we have fifteen additional orders for the next six months.’

The detector chip consists of a single continuous wire that becomes superconducting when cooled: electrical current that passes through it does not experience resistance. As soon as a photon falls on the chip, the wire loses its superconducting properties for a period of ten nanoseconds.

Superconducting nanowire

The detector chip consists of a single continuous wire of niobium titanium nitride, with a thickness of only five nanometres. This wire is cooled to minus 270 degrees Celsius. At that temperature, the wire becomes superconducting: electrical current that passes through it does not experience resistance. As soon as a photon falls on the chip, the wire loses its superconducting properties for a period of ten nanoseconds. During this short time interval, an electrical resistance is measured.

highlight-individuele-lichtdeeltjes-1A microscopic shot of the detector chip, consisting of 1 single thin wire.

Ahead of the competition

Whereas competing technology can detect one in ten passing photons, the detector made by the Delft company detects at least seven. The system is also substantially better than the existing detectors in other technical specifications, says Dorenbos. ‘There is less noise and the downtime between two measurements is far smaller.’

Development of a source

In recent years, the research group of Val Zwiller in Delft, where the detectors were initially developed, has also developed a single-photon source. ‘The sources are technically a special type of LED made from semiconductor materials. They are capable of controlling the emission of a single photon at a time.’

From science to a broader market

With the Valorisation Grant from NanoNextNL, the company will further develop this light source into a fully-fledged product. ‘Here too we will focus on science first,’ says Dorenbos. ‘We will use the experiences of research groups to improve our product. And the scientific articles that have been realised thanks to our technology can convince new clients about the quality of our products.’

Single Quantum is the only company in the world that can produce both single-photon sources and detectors. ‘We will focus on clients to whom we can sell complete systems, which could for example be used to do quantum cryptography experiments.’

Complete systems

At present, Single Quantum is the only company in the world that can produce both single-photon sources and detectors. ‘We will focus on clients to whom we can sell complete systems, which could for example be used to do quantum cryptography experiments. The jury for the Valorisation Grant has advised us not to be too modest in this regard. The scientific market is not large, but beyond that, we see big possibilities for our technology, especially within future forms of communication that use light instead of electronics. We are the first in the world to seriously try to turn this into a commercial success.’

Quick sales

‘It is unusual that a company with such a fundamental technology starts off with practical applications and clients,’ says Valorisation Grant jury member Willem van den Berg from Value Creation Capital. The technology has several unique selling points as a result of which the jury sees a lot of potential, he says. ‘There are applications for which the products of competitors are simply not sensitive enough. Single Quantum’s technology could be used to detect errors in integrated circuits (ICs). That is of major value to computer chip manufacturers.’ Van den Berg also sees sufficient market potential for the sources. ‘You could use these for quantum cryptography and quantum communication.’

Important phase

The company is now in an important phase, explains the jury member. ‘Many companies that are set up from within science are very content driven. That is good, as this is how this company has gained its first clients, for example. But the trick is to scale up on time. Production and assembly will not be a problem. But how do you establish a commercial basis for something like this? You need a different type of expertise for that. And then it comes down to sales, sales and more sales. It will be interesting to see how Single Quantum develops further.’

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