Danish researchers have now realized the complete platform for an optical quantum computer
Danish researchers have now realized the complete platform for an optical quantum computer

Insight

Danish researchers have realised the complete platform for an optical quantum computer

Insight

Danish researchers have realised the complete platform for an optical quantum computer

In new groundbreaking work, researchers from the Technical University of Denmark (DTU) have managed to realise the complete platform for an optical quantum computer. The platform is universal and scalable, can operate at room temperature and the technology is directly compatible with standard fibre optic networks. This puts Denmark at the forefront of the second quantum revolution.

When

Optical quantum computers have long been overshadowed by superconducting technologies that have been accelerated by huge development programs run at tech giants like IBM and Google. This is however changing with string of pioneering projects – one of them led by researchers at the basic research centre BigQ at DTU Physics.

In fact, the researchers at DTU are not limiting themselves to simply developing individual components for an optical quantum computer or just a quantum simulator. They are working determinedly on developing a universal measurement-based optical quantum computer.

Can run any arbitrary algorithm

Although the type of quantum computer that the DTU researchers are developing is conceptually very different from a normal computer, there are also similarities.



Instead of bits carrying information as in a normal computer, a quantum computer is based on qubits that carry the information and gates that perform operations on one or more qubits, thus implementing an algorithm. The demonstration of a so-called universal gate set - and the implementation of a number of operations by means thereof - is precisely what constitutes the new advance in optical quantum computing. 


"Our demonstration of a universal set of gates is absolutely crucial. It means that any arbitrary algorithm can be realized on our platform given the right inputs, namely optical qubits. The computer is fully programmable."

Mikkel Vilsbøll Larsen

PhD, Technical University of Denmark

Scaling makes quantum computer practically relevant 

The potential of the quantum computer is enormous. Its dramatically increased processing power relative to standard transistor-based computers will enable disruptive innovation in a wide range of areas of great importance to Denmark including the pharmaceutical industry, optimization of the transport sector and development of materials for carbon capture and storage.

A crucial factor in fulfilling this potential is that the quantum computer is realized on a platform that is scalable to thousands of qubits, explains Senior Researcher Jonas Schou Neergaard-Nielsen, who is one of the key researchers behind the platform.
"Theoretically, there’s no difference whether a quantum computer is based on superconducting or optical qubits. But there’s a decisive practical difference. Superconducting quantum computers are limited to the number of qubits fabricated on the specific processor chip. In our system, we’re constantly creating new ones and entangling them quantum mechanically with those we are performing calculations on. This means that our platform is easily scalable."

Jonas Schou Neergaard-Nielsen

Senior Researcher, PhD, Technical University of Denmark

The platform developed by researchers at DTU also has the advantage that it can operate at room temperature in optical fibres and does not have to cool down in large cryostats. This is a big advantage compared to other platforms as well as a stepping-stone in the realization of a future quantum internet where the platform potentially could be directly connected without difficult intermediaries.

A STEP CLOSER TOWARDS SCALABILITY

Generating large cluster states

The researchers at DTU passed the scaling milestone already back in 2019 when they, as some of the first in the world, accounted for how they had produced the basic structure for a measurement-based optical quantum computer—a so-called two-dimensional cluster state with over 30,000 entangled light states. Their work is published in an article in Science.

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  • Sarina Lohmann

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    Area: Copenhagen

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