A new research project aims to design, manufacture, and test light sources capable of emitting quantized light for use in future photonic quantum computers. The Innovation Fund Denmark has invested DKK 18.9 million in the project.

An international race is currently underway to develop the quantum computers of the future, which can solve complex computational problems in areas such as drug development, chemistry, and optimization - problems that today’s computers struggle to handle. Several companies, including Quandela in Europa and PsiQuantum in the United States, are betting on the photonic platform, where quantum calculations are performed using quantized light particles, also known as photons. However, today, no light sources exist that can efficiently deliver photons to large-scale quantum computers.

In a new research project called “Quantum Light Sources for Quantum Computing - QLIGHT”, a consortium consisting of DTU Electro, the Danish National Metrology Institute and the French company Quandela will solve this very problem. The goal is to develop highly efficient light sources that can be integrated into an industrial photonic quantum computing platform, thereby enabling far greater quantum calculations than is possible today. The high efficiency is to be achieved by placing a so-called quantum dot that emits the photons in a micro-pillar structure that directs the light emission into an optical fiber. To deliver high efficiency, the quantum dot must be manufactured in an ultra-clean environment using materials with extremely high purity.

- The technology is similar to that known from traditional semiconductor lasers. However, in order for the light sources to emit quantized light efficiently, stricter requirements are placed on the materials, says project leader Niels Gregersen, who is a professor at DTU.

Therefore, DTU has allied with the Danish National Metrology Institute, which will grow high-quality semiconductor material in an ultra-high vacuum in a newly established Molecular Beam Epitaxy machine.

Dr. Sabbir A. Khan, head of the Quantum Materials (QMAT) group at DFM, emphasizes the crucial role that ultrapure materials play in quantum computing platforms:

"The performance of photonic quantum devices is directly linked to the properties of the materials, which are designed at the atomic level. At DFM, our QMAT team focuses on precisely engineering and fine-tuning semiconductor structures atom by atom. Through this project, we aim to develop a highly efficient light source by optimizing the semiconductor platform," he explains.

Denmark is currently in a strong position within research into photonic quantum technologies.

- The overall project goal is to use DTU's know-how to deliver a technological solution that can contribute to the building and strengthening of the commercial Danish quantum industry, says Niels Gregersen.

Specifically, the investment from Innovation Fund Denmark will enable the development of experimental prototypes, the high performance of which has currently only been demonstrated numerically. These light sources will be tested in Quandela's industrial quantum computing platform, and at the end of the project, the launch of a Danish spin-out company is expected, which can supply light sources, for example, to Quandela.

The global international quantum technology market is rapidly developing, and the photonics segment alone is expected to be worth USD 6 billion by 2034. Although universal, fully functional quantum computers are still 10-15 years away, they are expected to revolutionize society by then by solving complex problems in cryptography, medicine, artificial intelligence, and materials science that today's classical computers have to give up on.

Facts

• Innovation Fund Denmark's investment: DKK 18.9 million.
• Total budget: DKK 23.4 million.
• Duration: 4 years
• Official title: Quantum Light Sources for Quantum Computing - QLIGHT

About the partners

DTU Electro is one of Europe's largest public research institutes in electronics and photonics, covering a wide range of optical disciplines including fundamental light-matter interactions and optical telecommunications, as well as applied research and innovation. Quantum technology is a central long-term research area at the institute.

DFM, the National Metrology Institute of Denmark, is a GTS institute with the highest level of measurement competence in Denmark across a range of critical measurements. It also houses Quantum Denmark, a central quantum initiative funded by the Danish government. In addition, DFM is part of the DIANA NATO Quantum Test Centre and the Danish Chip Competence Centre, where it supports both Danish and European quantum initiatives. With a strong background in quantum technology, standards and metrology, DFM specializes in quantum computing, quantum communication and quantum sensors.

Quandela is a leading French company in photonic quantum computing, founded in 2017. The company has developed into the leading provider of complete photonic quantum computing solutions and employs over 100 employees from 20 different nationalities, the majority of whom are researchers and engineers in optics, algorithms and information science.