From Niels Bohr Institute [Niels Bohr Institutet] (DK): “New invention keeps qubits of light stable at room temperature” 

Niels Bohr Institute bloc

From Niels Bohr Institute [Niels Bohr Institutet] (DK)

at

University of Copenhagen [Københavns Universitet] [UCPH] (DK)

17 June 2021

Eugene Simon Polzik, Professor
The Niels Bohr Institute
University of Copenhagen
+45 23 38 20 45
polzik@nbi.ku.dk

Ida Eriksen, Journalist
Faculty of Science
University of Copenhagen
+4593516002
ier@science.ku.dk

QUANTUM RESEARCH-Researchers from University of Copenhagen have developed a new technique that keeps quantum bits of light stable at room temperature instead of only working at -270 degrees. Their discovery saves power and money and is a breakthrough in quantum research.

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Photo: Eugene Simon Polzik.

As almost all our private information is digitalized, it is increasingly important that we find ways to protect our data and ourselves from being hacked. Quantum Cryptography is the researchers’ answer to this problem, and more specifically a certain kind of qubit – consisting of single photons: particles of light.

Single photons or qubits of light as they are also called are extremely difficult to hack. However, in order for these qubits of light to be stable and work properly they need to be stored at temperatures close to absolute zero – that is minus 270 C – something that requires huge amounts of power and resources.

Yet in a recently published study [Nature Communications], researchers from University of Copenhagen, demonstrate a new way to store these qubits at room temperature for a hundred times longer than ever shown before.

“We have developed a special coating for our memory chips that helps the quantum bits of light to be identical and stable while being in room temperature. In addition, our new method enables us to store the qubits for a much longer time, which is milliseconds instead of microseconds – something that has not been possible before. We are really excited about it,” says Eugene Simon Polzik, professor in quantum optics at the Niels Bohr Institute.

The special coating of the memory chips makes it much easier to store the qubits of light without big freezers, which are troublesome to operate and require a lot of power. Therefore, the new invention will be cheaper and more compatible with the demands of the industry in the future.

“The advantage of storing these qubits at room temperature is that it does not require liquid helium or complex laser-systems for cooling. Also it is a much more simple technology that can be implemented more easily in a future quantum internet,” says Karsten Dideriksen, a UCPH-PhD on the project.

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Photo of the memory chip, protected in a glasscell. Credit: Eugene Simon Polzik.

A special coating keeps the qubits stable

Normally warm temperatures disturb the energy of each quantum bit of light.

“In our memory chips, thousands of atoms are flying around emitting photons also known as qubits of light. When the atoms are exposed to heat, they start moving faster and collide with one another and with the walls of the chip. This leads them to emit photons that are very different from each other. But we need them to be exactly the same in order to use them for safe communication in the future,” explains Eugene Polzik and adds:

“That is why we have developed a method that protects the atomic memory with the special coating for the inside of the memory chips. The coating consists of paraffin that has a wax like structure and it works by softening the collision of the atoms, making the emitted photons or qubits identical and stable. Also we used special filters to make sure that only identical photons were extracted from the memory chips”.

Even though the new discovery is a breakthrough in quantum research it stills needs more work.

“Right now we produce the qubits of light at a low rate – one photon per second, while cooled systems can produce millions in the same amount of time. But we believe there are important advantages to this new technology and that we can overcome this challenge in time,” Eugene concludes.

See the full article here .


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Niels Bohr Institute Campus

Niels Bohr Institutet (DK) is a research institute of the Københavns Universitet [UCPH] (DK). The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics.

The Institute was founded in 1921, as the Institute for Theoretical Physics of the Københavns Universitet [UCPH] (DK), by the Danish theoretical physicist Niels Bohr, who had been on the staff of the University of Copenhagen since 1914, and who had been lobbying for its creation since his appointment as professor in 1916. On the 80th anniversary of Niels Bohr’s birth – October 7, 1965 – the Institute officially became The Niels Bohr Institutet (DK). Much of its original funding came from the charitable foundation of the Carlsberg brewery, and later from the Rockefeller Foundation.

During the 1920s, and 1930s, the Institute was the center of the developing disciplines of atomic physics and quantum physics. Physicists from across Europe (and sometimes further abroad) often visited the Institute to confer with Bohr on new theories and discoveries. The Copenhagen interpretation of quantum mechanics is named after work done at the Institute during this time.

On January 1, 1993 the institute was fused with the Astronomic Observatory, the Ørsted Laboratory and the Geophysical Institute. The new resulting institute retained the name Niels Bohr Institutet (DK)).

Københavns Universitet (UCPH) (DK) is the oldest university and research institution in Denmark. Founded in 1479 as a studium generale, it is the second oldest institution for higher education in Scandinavia after Uppsala University [ Uppsala universitet] (SE) (1477). The university has 23,473 undergraduate students, 17,398 postgraduate students, 2,968 doctoral students and over 9,000 employees. The university has four campuses located in and around Copenhagen, with the headquarters located in central Copenhagen. Most courses are taught in Danish; however, many courses are also offered in English and a few in German. The university has several thousands of foreign students, about half of whom come from Nordic countries.

The university is a member of the International Alliance of Research Universities (IARU), along with University of Cambridge (UK), Yale University (US), The Australian National University (AU), and University of California-Berkeley (US), amongst others. The 2016 Academic Ranking of World Universities ranks the University of Copenhagen as the best university in Scandinavia and 30th in the world, the 2016-2017 Times Higher Education World University Rankings as 120th in the world, and the 2016-2017 QS World University Rankings as 68th in the world. The university has had 9 alumni become Nobel laureates and has produced one Turing Award recipient.