Google and the XPrize Foundation have launched a $5 million competition to develop real-world applications for quantum computing that will benefit society – for example by accelerating progress on one of the UN Sustainable Development Goals. The principles of quantum physics suggest that quantum computers can perform very fast calculations on certain problems, so this competition could widen the range of applications where they have an advantage over conventional computers.

In our daily lives, the way nature works can generally be described by what we call classical physics. But nature behaves very differently on small quantum scales – smaller than an atom.

The race to harness quantum technology can be seen as a new industrial revolution, moving from devices that use the properties of classical physics to devices that exploit the weird and wonderful properties of quantum mechanics. Scientists have tried for decades to develop new technologies by exploiting these properties.

Considering how often we’re told that quantum technologies will revolutionize our daily lives, you might be surprised that we’ve yet to find practical applications by offering a prize. While there are numerous examples of success in using quantum properties for improved precision in detection and timing, there has been a surprising lack of progress in developing quantum computers that surpass their classical predecessors.

The main bottleneck holding back this development is that the software – which uses quantum algorithms – must demonstrate an advantage over computers based on classical physics. This is commonly known as ‘quantum advantage’.

A crucial way in which quantum computing differs from classical computing is in its use of a property known as “entanglement.” Classical computing uses ‘bits’ to represent information. These bits are made up of ones and zeros, and everything a computer does is made up of sequences of these ones and zeros. But quantum computing allows these bits to be in a ‘superposition’ of ones and zeros. In other words, it is as if these ones and zeros occur simultaneously in the quantum bit, or qubit.

It is this property that allows arithmetic tasks to be performed in one go. Hence the belief that quantum computing can offer a significant advantage over classical computing, as it is able to perform many computing tasks simultaneously.

* Read more: What is quantum advantage? A quantum computer scientist explains an impending milestone that marks the arrival of extremely powerful computers *

## Notable quantum algorithms

Although performing many tasks simultaneously should lead to a performance improvement over classical computers, putting this into practice has proven more difficult than theory would suggest. There are actually only a few notable quantum algorithms that can perform their tasks better than those using classical physics.

The most notable are the BB84 protocol, developed in 1984, and Shor’s algorithm, developed in 1994, both of which use entanglement to outperform classical algorithms on certain tasks.

The BB84 protocol is a cryptographic protocol – a system that guarantees secure private communications between two or more parties and is considered more secure than comparable classical algorithms.

Shor’s algorithm uses entanglement to demonstrate how to break current classical encryption protocols, because they are based on the factorization of very large numbers. There is also evidence that it can perform certain calculations faster than comparable algorithms designed for conventional computers.

Despite the superiority of these two algorithms over conventional algorithms, few beneficial quantum algorithms have been pursued. However, researchers have not given up on developing them. There are currently a number of main directions in research.

## Potential quantum benefits

The first is the use of quantum mechanics to assist in so-called large-scale optimization tasks. Optimization – finding the best or most effective way to solve a given task – is critical in everyday life, from ensuring traffic flow is effective, to managing operational procedures in factory pipelines, to streaming services that decide what to recommend to each user. It seems clear that quantum computers can help with these problems.

If we could reduce the computation time required to perform the optimization, this could save energy and reduce the carbon footprint of the many computers currently performing these tasks around the world and the data centers that support these tasks.

Another development that could offer far-reaching benefits is the use of quantum computation to simulate systems, such as combinations of atoms, that behave according to quantum mechanics. For example, understanding and predicting how quantum systems work in practice could lead to better drug design and medical treatments.

Quantum systems could also lead to improved electronic devices. As computer chips become smaller, quantum effects increase, potentially reducing device performance. A better fundamental understanding of quantum mechanics could help prevent this.

While significant investment has been made in building quantum computers, less attention has been paid to ensuring that they will directly benefit the public. However, that now seems to be changing.

Whether we will all have quantum computers at home within the next twenty years remains doubtful. But given the current financial commitment to making quantum computation a practical reality, it appears that society is finally in a better position to take advantage of it. What precise form will this take? There’s $5 million at stake to find out.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

*Adam Lowe does not work for, consult with, own shares in, or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.*