Welcome to the Computer Science page for The Quarters.

What is Quantum Computing?

Richard Feynman, one of the most important physicists, first proposed quantum computing in the 1980s, consequently forging the relationship that we currently see today, between physics and computer science.

Feynman desperately wanted to uncover the secrets of the quantum realm and to achieve this, he needed to directly observe quantum events in real-time. This feat, however, was impossible because of the fragility surrounding quantum systems, containing completely different sets of laws that we are unfamiliar with. Instead, he began to design a simulation capable of mimicking quantum events. Whilst performing such simulations it became apparent to him that his current computer systems were inefficient for such complex calculations.

Feynman, in his unrelenting pursuit of quantum knowledge, continued to contemplate a variety of methods to establish the simulation. During his studies, he reached a pivotal moment of insight, this breakthrough changed the trajectory of quantum mechanics forever. This concept laid the foundation of quantum computing, it was to create a computer system made up of quantum elements itself, using the laws of quantum physics.

In essence, quantum computing was originally proposed towards generating quantum simulations by performing complex simultaneous calculations.

Quantum Computers: How They Work and Why They’re Unique?

Classical computers and all the devices/embedded systems that surround us have one thing in common to process information, they use bits. Bits are fundamentally small units used in computing that represent either a 1 or 0, forming the foundation of computing to store and process information. However, the main limitation is that they can only be at a single state (1 or 0) at a time, restricting them to only solve complex computational calculations using trial and error. The world’s fastest supercomputer would be able to simulate 20 electrons but anything greater will require up to a lifetime of calculation before an accurate answer is returned, even with all the computers in the world operating together or, for a more constructive scale, if there was a supercomputer as big the world it would still be unable to solve it. 

On the other hand, quantum computers have the proficiency to solve it, very efficiently too. Quantum computers use qubits which is the basic unit for quantum information. Physically, qubits can be any quantum system containing two states (1 or 0), capable of being in any one of the two states at the same time, bypassing the limits of a normal bit. Additionally, due to the properties of qubits, theoretically, quantum computers can solve problems thought to be intractable on normal computers. Intractable problems are those that take extended periods to be solved, up to millions or billions of years.

Think of a qubit as a sphere, technically known as a Bloch Sphere, remember that when a qubit is measured for its value it collapses into either one of the two states (a 1 or 0). In the middle of the sphere, there is an axis (a point where an object rotates) with an arrow attached to this axis, this arrow can point in any direction. When the arrow points straight downwards the qubit collapses into a 0 when measured and when pointing straight upwards it collapses into a 1. However, the arrow can point in any direction, and when it does it is called a superposition state, meaning that when measured there is a probability for it to collapse into either state. The probability of a certain state increases when the arrow points closer to that direction (up or down).

Quantum physicists change this probability by taking advantage of the wave-like behaviours a qubit possesses so they can force qubits to predict the correct answers. Qubits have wave-like behaviours, as they can be represented as a wave function (mathematical version of a physical wave), and therefore experience some fundamental wave properties: superposition and interference. This is the reason why a qubit is in a superposition state; it has two amplitudes (two probability amplitudes) one for the qubit going into state 0 and another for the qubit going into state 0 which overlap so superposition occurs as the multiple states are added together to create the final wave function. 

Interference is then used to force the qubits to output the answer using two types of interference: constructive and destructive. Constructive interference causes a specific state’s amplitude to be increased, therefore increasing the chance that the state will return the correct result. Destructive interference causes a specific state’s amplitude to decrease, therefore reducing the chance of incorrect answers being outputted. This grants it the ability to solve intractable problems such as the Shor's algorithm.

What are the Problems Affecting Quantum Computers?

Qubits are very sensitive towards surrounding particles due to their property of entanglement. Entanglement is when qubits entangle with other qubits causing them to be a part of one quantum state, hence changing one of the qubit’s probability changes the others as well. Entanglement can also cause the qubits to entangle with the surrounding environment such as radiation from phones, noise, heat or any other type of rogue particle. This occurrence is called decoherence which induces the incorrect probability in qubits and is the reason for the incremental steps towards quantum computing. Currently, companies are trying to construct quantum computers with a zero percent error probability by using different particles to act as the qubits which are more stable and to perfect their quantum algorithms so they will always output the correct answer.

What is the Potential of Quantum Computing?

In 2019 quantum computers gained quantum supremacy as the Google Sycamore quantum computer with 53 qubits performed a calculation significantly faster than that of the world’s fastest supercomputer at that time, the Summit with 2.4 million CPU and GPU cores with 10PetaBytes of RAM, demonstrating that they can solve certain problems much faster than classical computers. The Sycamore completed the calculation in 200 seconds while the Summit was estimated to take 10,000 years to complete the calculation.

More recently, Microsoft revealed their new first quantum processing unit called the Majorana 1 chip after 17 years of research, this was said to be the beginning of the quantum age due to the massive leap forwards in quantum mechanics. The Majorana 1 is powered by a topological qubit using a newfound material called a topoconductor which they self-engineered. These topoconductors help create an entirely new state of matter only theorised by physicists until last year where they were able to physically observe it and are now capable of controlling and interacting with it; these exotic particles that can be used as qubits are called Majorana zero modes. These qubits are claimed by Microsoft to be stable, fast and digitally controlled - powerful by design and incorporating error resistance at the hardware level making it more stable by reducing the effect of decoherence. Microsoft’s team redesigned how they measured each qubit, vastly simplifying how quantum computing works, so it has the proficiency to scale up to 1 million qubits on a single chip, currently holding 8 qubits. The chip's initial measurement is at a 1% error probability, but Microsoft stated they are on their way to significantly reduce it.

It is believed by Microsoft and many other companies that reaching a system containing a million qubits can help us solve problems faced in many fields such as chemistry, material science and other industries. For instance: self-healing materials, catalysts to break down microplastics, and enzymes for more effective healthcare. Furthermore, people believe that merging AI and quantum computers will cause us to reach the peak of technological advancement, it would allow us to simply design and simulate a range of items and receive the correct product the first time, with no trial and error, AI can transform answers from quantum computers into language we can understand without any translation. Thus, we will be able to tackle problems at fundamental levels, finding new materials, new chemicals, and new discoveries to tackle the problems we face today.

Mankind is defined by the discoveries they make along the way, therefore what do you think would happen when we can radically gain the solutions to solve and fix problems to manipulate life around us?

References

https://www.youtube.com/watch?v=-UlxHPIEVqA&ab_channel=DomainofScience

https://en.wikipedia.org/wiki/Quantum_algorithm

https://www.ibm.com/think/topics/quantum-computing

https://builtin.com/hardware/quantum-computing

https://news.microsoft.com/source/features/innovation/microsofts-majorana-1-chip-carves-new-path-for-quantum-computing/