New nanoscience could produce huge speeds for photonic quantum computing

With great success, researchers at the University of Copenhagen and Ruhr University have found a way to control two sources of quantum light instead of one. Although the small step from one to two may sound too disciplined to be called a success, this new technology could be developed to create a quantum computer that corrects errors – which is often called the “holy grail of quantum computing”.

According to the University of Copenhagen, researchers around the world have been striving for years to develop stable sources of quantum light to achieve something known as quantum mechanical entanglement. In the context of photonic quantum computing, entanglement refers to when two light sources can be connected at once, possibly across large spatial distances. Entanglement is a concept central to the development of an efficient quantum computer.

When two light sources are installed, it means that if you control one light source, the other is also affected almost immediately. This technology can be extended to create networks of quantum lights, which can be used to perform “quantum bit operations” just like you do with ordinary bits in a computer.

The researchers were unable to make out the two light sources confused due to too much noise. “The problem is the very ‘charge noise’ of the carriers in the quantum emitter environment which gives rise to spectral jitter. We overcome this by using very clean materials and by using low noise power in the dot emitter. quantum,” Peter Lodahl, co-author of the research paper published in the journal. Sciencenotify via email.

In order to achieve this, the researchers used a nanochip as large as the width of a human hair. Five years ago, the team developed this nanochip, eventually improving its performance.

“We start with ultra-pure materials grown in a UHV molecular-beam chamber by our colleagues in Bochum, Germany. After that, we fabricate small chip devices using our proprietary processes. dedicated and very well tested. Finally, we create electrical connections to the samples and protect the tests from receiving excessive electrical noise,” explains Lodahl.

According to the researchers, this technology can be adapted to use 20-30 embedded sources of quantum light that could be used to build a “defect-corrected quantum computer,” an effort that companies in technology that pours billions of dollars into them.

Part of the research team is shown here. From left to right, Peter Lodahl, Anders Sørensen, Vasiliki Angelopoulou, Ying Wang, Alexey Tiranov, Cornelis van Diepen. Photo: Ola J. Joensen. (Image credit: Niels Bohr Institute)

The main difference between a classical computer and a quantum computer is their different rules, according to the EU Research and Innovation Magazine. Unlike classical computers, quantum computers do not use zeros and ones or “bits.” Instead, they work with “qubits”.

Bits can be thought of as a light switch – either on or off, one or zero. Qubits have a special property that allows them to exist in a space where they are both zeros and ones. This superposition will allow quantum computers to do things beyond classical computers.

“I think that quantum computers would be used more and more to solve difficult problems. For example, in the context of understanding complex chemical reactions such as drug discovery pipelines or for new engineering devices . Quantum computers are not very developed yet, and around the world, research is being done on different qubit formats, each with its own advantages and disadvantages,” Lodahl said, referring to various different quantum technologies.

“Photonics is an increasingly serious debate, mainly because it seems easier to reach large processors compared to other competing methods. Our work is a major step towards using deterministic sources single-photon for photonic quantum computing,” added Lodahl.

According to the researchers, it is very expensive for a university to build a set up where it can manage ten, fifteen or more resources. So now, it is up to other actors, such as private companies and laboratories, to continue the research work and find technological applications.

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