## The promises of quantum computing are great, and African physicists and computer scientists can now contribute to make them a reality.

The excitement around quantum computing keeps growing as researchers attempt to push the boundaries of what is possible with today’s quantum hardware. But is the promise of quantum computing really that alluring and, perhaps even more pertinent, is our excitement justified?

As a researcher in the field of quantum computing, you might think I am slightly biased in answering these questions—so instead, allow me to walk you through the basics of quantum computing, and let you decide!

### Why quantum?

I must admit, I never really understood physics that well in high school. I was aware that if I threw a ball, it would eventually fall to the ground, and my teacher would talk about equations, like Newton’s laws of motion, that can model or predict how far the ball would end up. What my teacher failed to mention, however, was that these equations belong to classical physics and merely approximate what we observe, whereas the true description of nature and our surroundings is in fact governed by quantum physics.

Classical physics provides the rules and mechanisms that our everyday computers used to store information and perform computation. Bits of information are usually represented in binary form, i.e., 1s and 0s. This is physically achieved by electricity flowing through a circuit, switching transistors *“on”* or *“off,”* which corresponds to bits being equal to 1 or 0. These strings of 1s and 0s form the building blocks of classical computation.

### Combinations of 1 and 0

Now, what if we created a computer that uses the principles of quantum physics to store information and do computation? This natural extension should immediately make you wonder two things: 1) can we store information differently, and 2) can we perform different computations?

The answer to both those questions is yes, and the device used to achieve it is a quantum computer. By exploiting quantum physics principles, we can build hardware that allows us to store bits of information in 1s and 0s, as well as linear combinations of 1 and 0.

### Non-classical correlations

We call these quantum bits of information, qubits, and the linear combinations are referred to as states of superposition. Qubits in superposition allow us to perform different operations in a circuit and this additional state provides more flexibility in how we encode information.

What is also cool about qubits is that they can interfere with each other and become correlated in ways that cannot be observed classically. This non-classical correlation is known as quantum entanglement. So, what exactly can we do with things like superposition and entanglement?

### Solving large combinatorial problems

It turns out that encoding information in linear combinations of 1 and 0 gives us a much larger space to work with, an exponentially larger space to be exact. With just 250 qubits, we can already represent more states (in superposition) than the number of atoms in the observable universe!

Researchers believe that this will allow us to solve large combinatorial problems far more efficiently than we ever could on classical computers. There have already been demonstrations of quantum advantage in factoring large numbers for example, which is important when it comes to cracking certain encryption methodologies. But large combinatorial problems present themselves in chemistry, optimization, and even finance—all promising areas for quantum computing to make an impact.

### Improving algorithms as well

Another important and ongoing research question is how can we use quantum resources, such as entanglement, to design faster, more efficient, or more interesting algorithms? This is an especially relevant question in the field of quantum machine learning which seeks to enhance existing machine learning approaches through use of quantum computers.

My research, in particular, involves the study of the power of quantum machine learning models relative to the ones used in practice on classical computers, such as neural networks. We are making interesting progress and finding increasing support for the use of quantum machine learning models. What’s exciting is that there is so much to uncover and the potential applications of quantum computing in general span so many domains.

### Learning about quantum computing

If what you have read so far has piqued your interest and you are wondering how you can learn more about how quantum computation works, you are in luck. There are tons of amazing, free resources out there to get started.

The Qiskit textbook introduces the basics, with excellent coding examples to make things concrete. If you are a hands-on learner, this is definitely a great place to start.

##### Happy participants at the Qiskit quantum computing camp in Switzerland, 2019. The author is the first on the left. Credit: IBM Research

### Theory resources

If you are keen on the theory, Nielsen and Chuang’s Quantum Computation and Quantum Information is the canonical textbook to become well acquainted with quantum computing algorithms. And lastly, if you would like something more formal, there are great lectures and courses on edX to get you going. From these resources, you will be able to discern what you like within quantum computing, whether it is how to build them, how to error correct them, or how to program them.

### Accessing a quantum computer

As an added bonus, IBM makes some of their quantum computers available for free via the cloud on the IBM Quantum Experience. Try creating a quantum circuit that entangles two qubits on the IBM Quantum Composer.

Here, you can create a quantum circuit with a specified number of qubits and drag and drop different quantum operations to see what effects they have on the quantum circuit. Once you have figured this out, as a challenge to yourself, try creating a circuit that measures the parity of the system and stores the result in the last qubit.

### An African network

As an African researcher, if you are affiliated with one of the universities in the ARUA network, you can also obtain access to premium devices that have more qubits. This is to encourage cutting edge research in Africa where there are many unique problems that could be tackled with non-traditional approaches, like quantum computing. Various research groups across the African continent have begun to make headway in quantum computing research, and the opportunities to study and learn quantum computing have grown steadily in the last two years.

There has also been increasing interest from various industries on how quantum computing is likely to impact the future of computing in Africa. Can HIV be better simulated with a quantum algorithm? Could tracking Malaria prove to be an easier task for a quantum computer? Or perhaps the more complex logistics and transportation constraints in Africa require quantum models

### It is up to you!

These are but a few lightly explored applications for quantum computing in Africa. Overall, the field is one that is rapidly progressing and rife for meaningful applications and high-quality research that can come from you, if you are fascinated—the resources to learn are easily available and the timing is right. And thanks to companies like IBM, we can begin to test, develop, and implement real world applications.

So, back to the original question: is the promise of quantum computing really that alluring and is our excitement justified? I guess we can’t really be sure yet, but in time, we will soon find out!

#### Amira Abbas, Quantum Computing Researcher, IBM Quantum and University of KwaZulu-Natal, South Africa

This article has first been published by the African Physics NewsLetter - © American Physical Society, 2021.