Quantum computer - What's so great about it? Full-scale operation of Japan’s first machine (1/2)

 Recently NHK News on-line reported the following:

量子コンピューター 何がすごい？国産初号機が本格稼働 (1/2)

2023年3月27日 20時03分

“次世代の計算機”として社会を大きく変えると言われる「量子コンピューター」。

従来のコンピューターとは桁違いの計算能力の高さで、新薬の開発や金融市場の予測など、さまざまな課題を解決することが期待されています。

これまでのコンピューターとはいったい何が異なるのか。その仕組みや実用化に向けた課題を解説します。

国産初の量子コンピューター 本格稼働

量子コンピューターの「量子」は光の粒や電子などの極めて小さな物質のことで、この「量子」の世界で起こる物理現象を応用することで超高速の計算が可能になるとされています。

理化学研究所は、国産の初号機を開発し、研究者が利用できるサービスを27日から始めました。

開発したのは、量子コンピューター研究における日本の第一人者で理化学研究所の中村泰信センター長や国内企業などからなる研究グループです。

中村センター長は開発の意義について「大規模な量子コンピューターの実現はチャレンジングな課題で、世界的に見てもまだまだハードルが高い技術だ。開発は長いレースになるので、われわれが技術的に貢献する余地は十分ある」と話していました。

理化学研究所の初号機は27日から本格稼働。当面は、共同で研究する契約を結んだ大学や企業の研究者に利用してもらい、さらなる改良や関連するソフトウエア開発などを加速させたい考えです。

超高速計算を可能にするのは？

量子コンピューターは、スーパーコンピューターなど従来のものと何が違うのでしょうか。その仕組みを解説します。

【従来のコンピューター】

まず、従来のコンピューターです。

コンピューターが計算を行う際、電気的なスイッチに置き換えます。

この際、電流を通すか通さないかの2択となります。

情報をすべて「0」か「1」で表し、この組み合わせで処理をします。

この状態が「ビット」で、基本単位となります。

実際は次のように計算しています。

例えば3桁の場合、その組み合わせは「000」「001」「010」「011」「100」「101」「110」「111」の全部で8通りあります。

このため、従来のコンピューターでは、あわせて8回の処理が必要になります。

【量子コンピューター】

一方、量子コンピューターの場合です。

量子の世界では「0」でも「1」でもある“重ね合わせ”という特殊な物理現象が存在します。これが「量子ビット」です。

この“重ね合わせ”を応用することで、従来のコンピューターでは8回の処理が必要だったプロセスが、わずか1回に。

こうした仕組みによって、超高速の計算が可能になるのです。

理化学研究所が開発した量子コンピューターの場合、頭脳にあたる集積回路には格子状にならんだ「量子ビット」が64あり「重ね合わせ」によって「2の64乗通り」の情報を同時に表せることを意味します。

高速で計算を繰り返す従来のコンピューターよりも計算の回数を減らせる可能性があり、計算の対象によっては、スーパーコンピューターをしのぐ桁違いに速いスピードで問題を解くことができると期待されています。

(to be continued)

Translation

Quantum computers were said to be “the next-generation computers” that would change society significantly.

With computing power that was way much higher than conventional computers, it was expected that it could solve various problems such as new drug development and financial market forecasting.

How was it different from the computer we were using so far? We would explain its mechanism and also challenges in turning it into practical application.

Full-scale operation of Japan's first quantum computer

The ``quantum'' of quantum computers referred to extremely small substances such as light particles and electrons, and it was said that ultra-high-speed calculations were possible by applying the physical phenomena that occur in this ``quantum'' world.

RIKEN (理化学研究所)had developed the first nation’s machine and from the 27th started a service that could be used researchers.

It was developed by a research group consisting of Yasunobu Nakamura (中村泰信), director of RIKEN, Japan's leading researcher in quantum computer research, and Japanese companies etc.

Director Nakamura commented on the significance of the development to say that, "The realization of a large-scale quantum computer is a challenging task, and even from a global perspective, the hurdles are still high. Development will be a long race, there is plenty of room for us to contribute technically."

RIKEN's first unit began full-scale operation on the 27th. For the time being, those researchers from universities and companies who had signed joint research agreements would use it, and to accelerate further improvements and related software development would be considered.

What makes ultra-fast computation possible?

What was the difference between quantum computers and conventional ones such as supercomputers? I will explain how it works.

[Conventional computer]

First is the traditional computer.

When the computer performed the calculations, it replaced/changed positions with an electrical switch.

At this time, there were two choices, whether to pass the current or not.

All information would be represented by "0" or "1", and processing would be performed with this combination.

This state was called a "bit", which was the basic unit.

The actual calculation would be as follows.

For example, in the case of 3 digits, there were a total of 8 combinations of ``000'', ``001'', ``010'', ``011'', ``100'', ``101'', ``110'', and ``111''.

For this reason, a conventional computer would require a total of eight dispositions.

[Quantum computer]

On the other hand, for quantum computers.

In the quantum world, there was a special physical phenomenon called "superposition" that was both "0" and "1". This was a "qubit".

By applying this "superimposition", the process that used to take eight times with a conventional computer could be reduced to just one.

Such a mechanism would enable ultra-high-speed calculations.

In the case of the quantum computer developed by RIKEN, the integrated circuit, which was the brain, there were 64 "qubits" arranged in a grid shape, and by "superposition", it means that "2 to the 64th power" information could be represented at the same time.

Compared to conventional computers, there was a possibility that the number of high-speed calculations done in repeating calculations could be reduced. Depending on the calculation target, the ability to solve problems at a superior magnitude faster than supercomputers could be expected.

(to be continued)

Note:

1. RIKEN (理研) is a large natural sciences research institute in Japan. Founded in 1917, it now has approximately 3,000 scientists on seven campuses across Japan, the main one in Wako, just outside Tokyo. RIKEN is an Independent Administrative Institution whose formal name in Japanese is Rikagaku Kenkyūjo (理化学研究所) and in English is The Institute of Physical and Chemical Research. RIKEN conducts research in many areas of science, including physics, chemistry, biology, medical science, engineering and computational science, and ranging from basic research to practical applications. It is almost entirely funded by the Japanese government. (Wikepedia)

2. In quantum computing, a qubit or quantum bit is a basic unit of quantum information—the quantum version of the classic binary bit physically realized with a two-state device. A qubit is a two-state quantum-mechanical system, one of the simplest quantum systems displaying the peculiarity of quantum mechanics. (Wikipedia)