With the advancement of artificial intelligence and virtual reality, the amount of data we need to process is increasing, but the limits of integrated circuits are approaching. Therefore, quantum computers, which use quantum mechanics as their operational principles instead of transistor gates, are emerging as a viable alternative. What exactly is quantum computing, and how can it be used as a solution? A reporter with no prior scientific background delves into everything from quantum computing to the current buzz, with a learning mindset.


Seeing major government agencies and global IT companies around the world pouring astronomical sums of money into developing quantum computers leaves me in awe. Just how incredible must it be that those smarter people than me are investing money I've never even touched in my life into it?
The D-Wave 2000Q, a commercial quantum computer (though not one that utilizes the quantum unwinding effect), would require an employee earning 100 million won annually to save every penny since the fourth year of King Cheoljong's reign in the Joseon Dynasty to purchase one. Of course, this also requires a home to house the D-Wave 2000Q and the ability to afford the steep progressive electricity tax.

In any case, there's a lot of money involved in quantum computing. However, the amount of money involved doesn't always mean the future of the field is bright. It can be bright or dark. Even the reporter doesn't know.


Is the future of quantum computing all that bright?
Quantum computer skeptics believe that qubits, the basic units of quantum computers, are fundamentally unsuited to performing the complex calculations required for quantum computers to function.
Gil Kalai, a mathematician at the Hebrew University of Jerusalem in Israel, is a leading quantum computer skeptic.

While attending a seminar on quantum computers at Yale University in the United States, Kalai suddenly had the thought, "Why is the future of quantum computers so bright?" and decided to tackle this issue in 2005.

Kalai studies computational complexity and noise. He argues that all physical systems exhibit noise, and that qubits, due to their extremely sensitive "superposition" properties, inevitably exhibit noise when interacting with the outside world. He argues that reducing this noise is not a technical problem; rather, the fundamental theory of computation determines the minimum value of this noise.

Quantum computers are also affected by surrounding signals. During each processing step of a quantum computer, qubits are more susceptible to noise contamination than conventional bits. To clean up qubit contamination, quantum error correction (QEC) technology is required. This requires 100 to 500 physical qubits for each sophisticated logical qubit. For quantum error correction circuits to function, the overall noise must be below a certain value.

In an interview with Quanta on February 7, 2018, Kalai's research team announced that they had mathematically modeled noise and calculated its specific value. Kalai used Fourier analysis to examine what happens when errors caused by noise are correlated. They found that while the system remains stable when the error waveform is low-frequency, the entire process becomes affected by the error at high frequencies.
Unlike many quantum computer researchers, Kalai believes this result suggests that noise may never be reduced below a certain level—the level required for quantum supremacy, or quantum error correction. Quantum supremacy is when a quantum computer outperforms a classical computer. If quantum computers cannot achieve quantum supremacy, there's no point in developing them.

To summarize Kalai's argument, errors occur in qubits during each processing step of a quantum computer, requiring additional qubits to correct them. For this process to be successful, noise must be low, but achieving that level of noise is inherently impossible. Despite this, quantum computer researchers continue to pursue quantum computing. Kalai is certain this attempt will fail, yet he waits to see what happens. It's truly quantum mechanical.


Looking to the future of quantum computers
What comes to mind when you think of IBM's quantum computer? Isn't it incredibly large? Like earlier computers like ABC, Colossus, and ENIAC, the IBM Q is large, heavy, and consumes a lot of power. The reason is different. As Kallay pointed out above, it uses cooling to reduce noise levels and qubit errors.
The lower the Kelvin, the closer it gets to absolute zero, the slower the motion of atoms becomes. The more atoms bounce around, the higher the error rate. Therefore, IBM Q maintains the temperature of its qubits at 0.015 Kelvin, necessitating a larger cooler and, consequently, a larger computer. Having more qubits isn't always the answer.

Nevertheless, quantum computer development continues. One day, we may be able to carry a quantum computer around like a laptop.

Currently, Samsung Electronics, in collaboration with IBM, is the only domestic company researching quantum computers. IBM Korea plans to announce the companies, institutions, and universities that will collaborate with IBM on quantum computing research in the first half of 2019.

Just like the noise problem, the fact that many challenges remain before commercializing quantum computers suggests that opportunities remain for Korea as well. However, it's undeniable that we lag behind the US, China, and Japan in some areas. To close the gap that has already developed, selective attention and focus are necessary.

Focusing on special-purpose quantum computers like D-Wave rather than general-purpose quantum computers is also a viable option, as is acquiring overseas startups with superior technological capabilities. SK Telecom's acquisition of quantum cryptography company IDQ is a prime example.
Forecasting organizations, including Gartner, are predicting that quantum computers will become a means of enhancing competitiveness in the Fourth Industrial Revolution. We can no longer afford to delay the development of quantum computers. It's time for the comprehensive mobilization of capabilities across relevant authorities, businesses, and universities.

<End>

This concludes our series on quantum computing with Part 12. Even for experts, this is a challenging field, and I apologize to my readers for only scratching the surface. I will study more and prepare more to return with more substantial articles on quantum computing.