On the future of quantum computing

An Introduction

“I do not like it, and I am sorry I ever had anything to do with it”.

This was Erwin Schrodinger, a pioneering quantum scientist, on the nature of quantum physics, and this sentiment will probably be echoed when you glance at the almost unrealistic nature of quantum science.

Years later, however, this very theory could serve as the basis for the future of all computing and could be the scientific community’s next step towards solving global crises, or perhaps simply another expensive wasted attempt at salvation, like many before.

What is it?

Essentially, quantum computing is an emerging and highly developing industry situated in the multidisciplinary area between math, physics and computer science, which harnesses the laws of quantum physics, such as superposition and entanglement, to solve problems that your Windows Vista PC probably can’t.

Fundamental Principles

A defining factor of quantum computing is its application of the qubit. In our household computers, bits are represented by either 0 or 1 and are stored inside the computer as a feeble electric charge. These bits are then manipulated by various read/write machines that control the flow of instructions in a computer.

A qubit, however, acts almost exactly the same, but with a twist - it can exist as both a 0 and 1 at the same time, as well as any combinational probability in between.

The classic way to demonstrate quantum bits is by shining a light through a barrier with two slits. Some light goes through the top slit, some through the bottom, and perhaps knocking into each other, resulting in a higher/lower amplitude.

But now dim the light until you’re firing individual particles, one by one. Logically, each photon has to travel through a single slit, and they’ve got nothing to interfere with. But somehow, you still end up with different patterns. We only realize the position/final location of the particle, when we observe it through a screen.

In reality, qubits can exist as several different particles.

An atomic nucleus is one kind of qubit. The direction of its momentum, or spin, can point in different directions, say up or down, depending on the nature of the magnetic field. 

Another idea is to strip an electron off the atom and turn it into an ion. Then you can use electromagnetic fields to suspend the ion in free space, essentially having no disturbing forces of particles affecting it, allowing us to fire tiny lasers at it to change its state.

A photon of light can also be in superposition, depending on how its wave moves. Some groups have been assembling quantum circuits by sending photons around a maze of optical fibres and mirrors.

But how can it exist in multiple states? To understand this, we need to understand quantum superposition.

Here, one popularly refers to ‘Schrodinger’s cat’ thought experiment, in which a cat is placed inside a closed container, with a radioactive metal, a Geiger measure and a flask of poison. When the Geiger counter measures any radioactivity, which is when a single atom decays, the flask is shattered and the cat dies. From the outside, one can consider the cat to be simultaneously alive and dead, for we do not know if and when this random event may occur.

In another example perhaps more to your liking, when we solve x2 = 4, x can either be 2 or –2, with both answers being correct. Superposed wave functions, while much more complex, are similar, and can be approached with the same mindset.

In our final thought experiment, think of flipping a coin. While the coin is in the air, we cannot know whether it is heads or tails - it is merely a combination of both. Only when it falls do we know the outcome.

This is mainly caused by the property of electrons and photons to behave in certain circumstances like a wave, allowing the particles to have non-zero probabilities for multiple states at the same time, hence superposing into all these states simultaneously.

Since quantum bits can exist as electrons, photons or nuclei, the very particles that exhibit superposition, these very laws apply there, allowing them to represent multiple values while unobserved, and crashing down on one when measured.

While this concept is certainly quite difficult to wrap your head around, it is a cornerstone in physics and serves as the basis for most sub-particulate research.

This property thus helps quantum computers become much faster, as they can take advantage of the superposition in quantum bits, to perform multiple calculations at once, by manipulating the spin, or value here, of the qubit. For the mathematically inclined, we can say that each quantum bit can represent 2X values at once.

The Future

With all this in mind, is quantum computing the future?

Well, maybe.

Its impact on our daily lives is unfortunately likely minimal, for you don’t really need extreme computational power to watch the 345345th episode of “One Piece”. The real renaissance emerges when we look at its applications in demanding industries, such as our governments, corporations and research centres, for quantum computing may allow them to unlock pathways to the future.

An important example could be the popularly demonstrated problem, in which a computer is tasked with finding all the prime factors of a very large number.

While this can take years for traditional machines, quantum computing can solve these computational problems in a few hours at most.

However, as you may have guessed, the field is still in its infancy, and there remain many challenges that are yet to be resolved.

One predominant problem is the actual maintenance of these qubits, which can be extremely finicky to handle, especially concerning properties like superposition. To truly harness the power of quantum computing, we need to understand how to practically and efficiently maintain the various states of qubits to take the technology to scale.

Another issue is that these particles are extremely finicky, Hollywood divas if you will, for they require extremely low temperatures, close to absolute zero, and need to be completely isolated to be manipulated. At the end of the day, this is a major hindrance to the size and overall practicality of quantum computers.

Another major complication that results from this fragility is the huge area for error, with qubits being extremely susceptible to errors. Developing efficient, reliable and practical error correction methods will be at the forefront if quantum computing truly is the future.

Most other issues stem from the project being extremely theoretical/specialised as of now, with many suspicious of its ability to transpose into practical areas effectively. To do so, it will need to be much cheaper, diminish its power consumption and develop more practical overall hardware.

Conclusion

Quantum computing, as we have covered, truly has the potential to be the future of computing, with its intricate quantum properties possibly acting as our gateway to a better future, but will it be able to overcome its significant practical adversities?

Only time will tell.