Devising a new method that reduces computation time and points to the potential of photonic quantum computation

Tokyo – Toppan, a global leader in communication, security, packaging, décor materials, and electronics solutions, and blueqat, a leading venture company in the fields of quantum software and machine learning solutions, are collaborating on research on photonic quantum computation.1 A paper on the research has been included in the Posters Program of the International Conference on Quantum Computing and Engineering (QCE), organized by the Institute of Electrical and Electronics Engineers (IEEE).2 The paper was presented at 14:30 (MST) on October 18.

The research paper concerns the establishment of a new approach that reduces computation time for the photonic quantum method of quantum computing. The use of this new method is expected to enable high-speed photonic quantum computation in the future.

About the research paper

Title: Simulation of Continuous?Variable Quantum Systems with Tensor Network
Authors: Ryutaro Nagai (blueqat inc.), Takao Tomono (Toppan Inc.), Yuichiro Minato (blueqat inc.)
https://qce.quantum.ieee.org/posters-program/ 

Background to the research

Quantum computers have garnered increasing attention in recent years as next-generation machines providing high processing capacity. Research institutions, computer companies, ventures, and other businesses targeting practical application are developing hardware, computation methods, and network technologies. Hardware development in particular is in its early stages, and various methods are being considered to enhance processing power. Development of the superconducting3 method is showing the most progress, but operating temperatures need to be close to absolute zero (-273?). Cooling therefore requires large-scale equipment and consumes a huge amount of energy, and the creation of more compact equipment is a significant challenge. In contrast, the photonic quantum method can be performed at room temperature and consumes only small amounts of energy, enabling devices to be compact. This has fueled anticipation of potential for commercial use, but research on computation methods is not yet sufficient, and interest is therefore currently focused on the establishment of such techniques.

Toppan and blueqat have addressed this challenge by taking advantage of their accumulated knowledge on the handling of photons and quantum information to devise a new method for photonic quantum computation. The two companies have succeeded in reducing computation time to one twenty-seventh of the time taken using previous methods. This is expected to accelerate photonic quantum computation going forward. Through a digital transformation (DX) business employing photonic quantum methods, the two companies also aim to contribute to expanded use of quantum computers and quantum communication that enable a safe and secure digital society in the future.

Overview of the research paper
1) Establishment of photonic quantum computation method
By using tensor networks4 as a means to simulate quantum computation, Toppan and blueqat have established a method for creating photonic quantum circuits, conducting photonic quantum computation, and reducing computation time.

2) Application of tensor network structure to CV quantum computation
This new technique has resulted in reducing computation time by applying singular value decomposition in tensor network structures called Matrix Product States (MPS)5 to continuous-variable (CV) quantum computation.6 The effectiveness of the new computation technique has been confirmed in comparison with previous techniques. Going forward, Toppan and blueqat will conduct further comparison against other methods and verify effectiveness.

Diagram of photonic quantum circuit (left) and graph of results indicating reduction in time (to one twenty-seventh)

Roles of the companies

Toppan
Toppan is leveraging its know-how on the handling of photons to advance research and development on quantum computing using the photonic quantum method. Toppan has devised a method for analyzing photonic continuous-variable modes. The company intends to further enhance this method and apply it to photonic quantum circuits and quantum communication using such circuits.

“It’s well known that quantum computers have the potential to contribute to solutions for a range of social issues,” said Takashi Ito, Executive Officer of Toppan’s Digital Innovation Division. “The photonic quantum method is expected to be widely used because room temperature operation is possible and it saves energy, making it a technology that can bring us closer to quantum computers. I hope the results of this research help to drive the practical use of quantum computers using the photonic quantum method.”

blueqat
blueqat will make use of its extensive knowledge of quantum information to drive the development of photonic quantum computer software (the “photonqat” simulator). More specifically, blueqat has devised a method for incorporating tensor networks into photonic quantum computation. The company plans to further advance the computation method and apply it to the development of middleware.

“We are starting to see photonic quantum computers being applied for society around the world, and potential for their application is not limited to computation, but is expected to extend to communication and a wide range of other fields,” said Yuichiro Minato, blueqat CEO/CTO. “This research focuses on a technology that can form a bridge between fundamental research and application, and we believe it will advance the practical use of photonic quantum computers significantly.”

Toppan and blueqat will conduct fundamental research on photonic quantum computation, including computation methods and algorithms, targeting industrial application of a quantum computing business through the development of software and device technologies.

1. Photonic quantum computation is a quantum computing method in which particles of light (photons) are used as carriers of quantum information.
2. The Institute of Electrical and Electronics Engineers (IEEE) is the world’s largest academic research organization for the electrical and information engineering field. Based in the United States, it has in excess of 423,000 members in more than 160 countries.
https://www.ieee.org/ 
3. Superconducting is a quantum computing method that uses superconducting elements as quantum bits.
4. A tensor network is a technique for efficient computation of quantum systems.
5. Matrix Product States (MPS) are tensor networks formed by the accumulation of multiple lines.
6. Continuous-variable (CV) quantum computation refers to photonic quantum computation using the continuously changing values of light phase and amplitude.

About the International Conference on Quantum Computing and Engineering?(QCE)

Launched in 2020, QCE is one of the largest annual international conferences on quantum computing and engineering for the quantum industry. The conference includes the presentation of papers and a program of poster sessions from a perspective that differs from regular academic and business conferences to bridge the gap between the science of quantum computing and the growth of the related industry. More than 800 experts from 45 countries and regions participated in the first conference in 2020. Even more participants are expected for this year’s event, which will be held completely online from October 17 to 22.
https://qce.quantum.ieee.org/ 

About blueqat

blueqat is a leading venture company in the fields of quantum software and machine learning solutions with a mission to solve humanity's unsolvable problems. blueqat has developed various software systems since its establishment in 2008 and entered the quantum computer business in 2014.
https://blueqat.com/?Japanese