## As quantum computing technology develops, people are hard at work identifying and creating potential applications for quantum computers.

Many of those applications are directed to fundamental societal needs, such as expedited development of effective vaccines and medicines, protecting confidential data and networks from cyberattack, and determining the scope of climate change, including prediction of how that change may affect weather and climate. These are but a few of the applications under current development, and a mere drop in the bucket of future quantum computing applications. In this regard, the evolution of the Internet is instructive. The omnipresence of the Internet and pervasive Internet applications of today were unimaginable as the Internet evolved in the 1990s. Quantum computing will surely follow a similar explosion in future applications.

The basic proposition that underlies quantum computing applications is a simple one: some problems now require so many calculations to solve that they cannot be completed in a reasonable time – if at all – with conventional computers. Algorithms typically require evaluation of all of the different permutations of data to identify the optimal permutation. Conventional computers methodically evaluate each permutation to find the best. The fundamental problem with this approach is that the number of permutations grows exponentially with the number of data points included in each permutation. As a result, conventional computers cannot reasonably perform these calculations as the complexity of permutations grows. In contrast, quantum computers allow the required calculations to follow a path of evaluating only a limited number of the total possible permutations, vastly reducing the time to arrive at the solution.

## There are a number of potential applications that are believed will become practicable using quantum computers. Three examples relate to some of the most important problems facing the world today.

A first example is the development of molecules that can be used as pharmaceutical products. A lesson of the last year is that the prompt development of effective drugs and vaccines can eliminate substantial ongoing death and suffering. In traditional research, scientists make a reasoned judgment about what molecules are likely to be effective drugs, and then engage in a lengthy trial and error process performing physical experiments on the identified molecules, which takes substantial time to complete and often results in failed drug candidates. In theory, computers could be used to model the interactions of atoms in the candidate molecules and in proteins to narrow testing to more promising molecules. The problem is that such molecules and the proteins with which they interact have too many atoms for modeling of interactions to be performed in a reasonable time, given the exponential number of calculations that would be required. Quantum computers can reduce the number of permutations that must be evaluated – and the required number of calculations – to the point where such modeling can be completed in a reasonable time to expedite the development of drugs.

A second example relates to cyberattacks on data and networks by criminals, foreign governments, competitors and the like. At the present time, various techniques are used to encrypt data, and many are effective because their “code” cannot be broken. That has been changing with increased conventional computing power. Quantum computing provides both a shield and a sword in this application. Quantum computing, as a shield, would allow for the complexity of an encryption scheme to be increased to the point where it could no longer be broken by conventional computers. However, quantum computing, as a sword, would allow for the security of current encryption algorithms – and for future quantum-based algorithms – to be compromised (which is not necessarily bad, for example, in law enforcement applications). As with conventional algorithms, there will likely be a continual struggle between protection and compromise of data and networks protected by quantum-based security.

## A third example is the application of quantum computing to climate data, which is laden with a myriad of factors to be considered in modeling.

Quantum computing can be used to enhance prediction of adverse weather conditions, such as long-term temperature change, storms, flooding, drought, forest fires and rising sea level. Quantum computing can also be used to help understand the degree and effect of global warming.