Both the E6 and Västkustbanan sweep close to the office building in Kallebäck. Nevertheless, no traffic noise is considered on the thirteenth floor, where Low Noise Factory is located. Instead, here is another kind of noise in the center. Namely, the inevitable signal noise that occurs in all electronics, including the random movements of the electrons in semiconductors.
In the company's transistor-based amplifiers, this noise is reduced to an absolute minimum. How?
Well, you benefit from phenomena that only occur on a nano-scale, with exotic materials such as indium phosphide and - in most cases - through cryogenic use. That is, cooling to a few degrees above absolute zero.
"The vast majority of applications do not benefit from such a low noise. It is fine with something worse and cheaper", explains the company's founder and principal owner Niklas Wadefalk (to the right).
One exception is the radio astronomy, which is trying to capture extremely weak signals from space.
"It is usually said that the sensitivity of a radio telescope is equal to the capture area divided by the system noise. This means that the sensitivity can be improved either by larger antennas, which can cost millions, or by less noise in the amplifier", explains Niklas Wadefalk and adds that the latter becomes considerably cheaper.
It was precisely to meet the demanding radio astronomers' needs that he started the company thirteen years ago. He had previously worked for a few years as a research engineer at Chalmers and learned to build cryo-amplifiers. Such amplifiers had long been an important research area at Chalmers, driven by recurring assignments to build single-piece amplifiers for different space projects, including for the Odin satellite. Then Niklas Wadefalk was attracted to the Caltech University in California, where for five years he further developed the design of the cryo amplifier. During these years the radio astronomy changed. Gradually, they began to plan future telescopes in the form of many, small scattered antennas instead of single large ones.
"Hence, hundreds, perhaps thousands of low noise amplifiers would be needed, something that universities and research institutions would hardly be able to produce themselves. I saw a niche for a commercial and serious company that could provide guarantees and ensure continuity."
He decided to move home to Gothenburg and Chalmers again, while he started Low Noise Factory alongside. Bit at first, it wasn't so much of a factory. The company's first amplifier, Niklas Wadefalk manufactured in his own bedroom. But graduallt, orders rolled in.
Inside the Low Noise Factory's best-selling amplifier, popular in both quantum research and radio astronomy.
Since the core component itself, the half-millimeter-sized transistors, was processed in Chalmers cleanroom, a steep learning curve was also initiated in production technology at Chalmers. At the start, a few hundred transistors were manufactured on centimeter-sized pieces of indium phosphide.
"Today, 50,000 transistors can be placed on a "wafer" large as a CD. It has been an avalanche development thanks to all the feedback between us and Chalmers."
Another big change is that many amplifiers are now made in the form of an integrated circuit, which minimizes the need for manual mounting work on the microscope.
With a pincette, one of the fifty thousand transistors from the "wafer" manufactured in Chalmers clean room is picked to become a core component of a new amplifier.
Low Noise Factory is today, with its nine employees, almost alone in the world to manufacture cryogenic amplifiers for the very highest low noise requirements.
The production rate is now up to a thousand units per year. But the radio astronomers are not behind the recent increase in order intake. Instead, the orders come from the many universities and IT companies that are competing to create the first useful quantum computer.
"It is a large and growing market for us, but it also means new and higher demands."
One demand applies to the heat development of the amplifiers. Quantum computer scientists think that 4 kelvin is too hot, they prefer to go down in millikelvin.
"It is not certain that it is possible to use transistor amplifiers for this, but we are researching with Chalmers to get further."
It will probably be in the form of the same kind of tangible experimentation that has so far yielded results. According to Niklas Wadefalk, there is no exclusive theoretical knowledge or "business secret" that lies behind the company's dominance within its niche.
"There is some feature of our transistors that makes them better than any other at cryogenic temperatures. Something we have come up with through a lot of trial-and-error. But exactly what, we don't actually know."
Text: Björn Forsman
Photo: Anna-Lena Lundqvist
Previously published in Chalmers magasin, no. 2, 2018.