With the development of artificial intelligence and virtual reality, the amount of data to be processed is increasing, yet the limits of integrated circuits are being approached. Consequently, quantum computers, which use quantum mechanics as computational rules instead of gates made of transistors, are emerging as an alternative. But what exactly is a quantum, and how is it used to be considered a viable alternative? A journalist with no prior connection to science takes a step-by-step look, starting from quantum mechanics to the recently trending quantum computers, with a learning mindset.


The foundation of modern civilization, semiconductors
Can you imagine daily life without semiconductors?
All objects that use electricity contain semiconductor devices and are controlled by them. Electronic machines containing semiconductor devices support our daily lives, from production to entertainment.

AI, IoT, AR, VR, and autonomous vehicles are all things that would be impossible to even dream of without semiconductors. If it weren't for semiconductors, our lives would have been stuck in 1947, before the transistor was developed.

Semiconductors and semiconductor devices utilizing semiconductors are the power that sustains modern civilization.


What is a semiconductor?
Electrons exist within atoms. Under certain conditions, electrons can escape the confinement of the atomic nucleus, move freely within certain materials, and form an electric current. Most metals, such as gold, silver, and copper, are conductors that hardly hinder the movement of electrons. On the other hand, rubber, glass, and plastic are insulators that hinder the movement of electrons.
Some materials are special. They are semiconductors. Under normal circumstances, they hinder the movement of electrons, but when placed under special external conditions, they no longer hinder it. Silicon and germanium fall into this category. According to quantum mechanics, electrons can appear anywhere in the electron cloud surrounding the atomic nucleus. By controlling the external conditions of a semiconductor, we can control the movement of electrons and the formation of electric current.


diodes and transistors
Semiconductor devices, made using semiconductors, are now found everywhere. Diodes and transistors are two representative semiconductor devices. A diode generates current when voltage is applied in one direction. When applied in the opposite direction, no current is generated. A diode, which has two terminals, acts as a switch in a circuit.

A transistor has three terminals. The three terminals are the input terminal, the common terminal, and the output terminal. When voltage or current is applied between the input terminal and the common terminal, the electrical conductivity between the common terminal and the output terminal increases, thereby controlling the flow of current between them. A transistor can amplify current while also acting as a switch.

Through the characteristics of such semiconductor devices, humans can issue repetitive commands to machines that are not human. If so, who was the first person to create this semiconductor device?
American physicists John Bardeen, Walter Brattain, and William Shockley worked at Bell Laboratories and researched devices to replace vacuum tubes. In 1947, Bardeen and Brattain succeeded in developing the transistor using Shockley's electric field theory.

The term "transistor" is derived from "transfer of a signal through a varister/transit resistor." After its development, the transistor brought about a major revolution in electronics. The advent of the transistor led to the development of smaller and cheaper radios, calculators, and computers.


The man who brought silicon to Silicon Valley
In 1953, Shockley, feeling that he was not receiving adequate treatment for his achievements at Bell Labs, stormed out of the institute. And in 1955, he got a job at Beckman Instruments in San Jose, California, and took charge of the 'Shockley Semiconductor Laboratory'.
Shockley wanted to bring in his former colleagues from Bell Labs. However, since Shockley Semiconductor Labs and Bell Labs were located at opposite ends of the American continent, no one was willing to come. Furthermore, his former colleagues, who knew Shockley's personality well, had no intention of working with him again. This was because Shockley's personality was simply too eccentric. In the end, although Shockley had gathered outstanding graduates using his reputation and the financial power of Beckman Instruments, all he received in return was betrayal.

In 1957, when his secretary injured her thumb, Shockley claimed it was a plot to poison him and conducted lie detector tests on all employees. The results revealed that a broken thumbtack had injured the secretary's thumb, and the atmosphere at the laboratory quickly became hostile. Later that year, eight key employees left Shockley's side. These eight employees, known as the "Eight Traitors," founded Fairchild Semiconductor and wrote the history of the semiconductor industry.
Meanwhile, Shockley, who was no longer able to run a business, closed it down in 1960 and became a professor at Stanford University. He later caused social unrest by publishing a racist paper claiming that the IQ of Black people was lower than that of white people, and passed away in 1989.

While opinions on Shockley are divided, what is certain is that he was the man who brought silicon—that is, semiconductors—to Silicon Valley. There are no silicon mines in San Jose and its vicinity, which we commonly call Silicon Valley. It is merely a nickname given because there are many semiconductor companies and a large valley nearby. Had Shockley not left Bell Labs, and had the eight traitors not abandoned Shockley, the term Silicon Valley would not exist.


Limitations of Integrated Circuit Development Become Visible
At Fairchild, eight traitors designed to integrate four transistor circuits onto a single silicon wafer, creating the first silicon integrated circuit. After manufacturing integrated circuits for a while, they left the company one after another to establish several companies. While National Semiconductor and AMD are well-known, the most representative company is Intel, founded by Gordon Moore and Robert Noyce in 1968.
In 1971, Intel released the Intel 4004, the first commercial microcontroller, and later established itself as the most important company in computer history by supplying the Intel 8088 to the IBM PC.

In 1965, Gordon Moore announced the law stating that the performance of a $1,000 semiconductor integrated circuit doubles every 24 months. Fifty years later, the performance of semiconductor chips has increased 200 million times compared to the first integrated circuit. The smallest commercially available chip currently measures 7 nm.

However, Moore's Law is bound to be broken. Due to the tunneling effect of quantum mechanics, even if integration density is increased from 5nm onwards, the gap between the paths electrons travel becomes narrower, causing interference in communication between devices, such as electrons warping to other locations. There are physical limitations to increasing computer performance with existing methods.
To overcome this limitation, physicists devised a computer that operates according to the principles of quantum mechanics, and that is the quantum computer.

We have examined the history and content of semiconductor devices that apply the principles of quantum mechanics. In the next installment, we will briefly look at the concepts and principles of quantum computers.