Finnish scientists set new record in microwave detection

Scientists at Finland's Aalto University have set a new world record in microwave detection, breaking the old record by fourteen-fold -- a feat that may lead to manufacturing of ultrasensitive cameras and accessories for the emerging quantum computer.

The record was made using a partially superconducting microwave detector. The first of the two key enabling developments is the new detector design consisting of tiny pieces of superconducting aluminum and a golden nanowire.

This design guarantees both efficient absorption of incoming photons and very sensitive readout. The whole detector is smaller than a single human blood cell, according to the scientists.

"For us size matters. The smaller the better. With smaller detectors, we get more signal and cheaper price in mass production," said Mikko Mottonen, the leader of the record-breaking Quantum Computing and Devices research group.

The European Research Council (ERC) has recently awarded Mottonen a prestigious proof of concept grant to develop the detector towards commercial applications.

The new detector works at a hundredth of a degree above absolute zero temperature. Thermal disturbances at such low temperatures are so weak that the research team could detect energy packets of only a single zeptojoule. That is the energy needed to lift a red blood cell by just a single nanometre.

The second key development concerns the amplification of the signal arising from the tiny the energy packets. To this end, the scientists used something called positive feedback, which means that there is an external energy source that amplifies the temperature change arising from the absorbed photons.

Microwaves are currently used in mobile phone communications and satellite televisions, thanks to their ability to pass through the walls.

More sensitive microwave detectors may lead to great improvements of the present communication systems and measurement techniques.

"Existing superconducting technology can produce single microwave photons. However, detection of such travelling photons efficiently is a major outstanding challenge. Our results provide a leap towards solving this problem using thermal detection," said Joonas Govenius, the first author of the work.

--IANS

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