## Abstract

This paper considers the potential impact that the nascent technology of quantum computing may have on society. It focuses on three areas: cryptography, optimization, and simulation of quantum systems. We will also discuss some ethical aspects of these developments, and ways to mitigate the risks.

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## Notes

The first digital computers were built a few years later. Of course, there was already much earlier (informal) work, like Pascal and Leibniz’s 17th century work on machines for arithmetic calculations, Babbage and Lovelace’s 19th century work on the Analytical Engine, and even the still-mysterious 1st century BC Antikythera mechanism.

In the theory of computing, a computational problem is considered “easy” if it can be computed by an algorithm whose running time grows at most polynomially with the input length (i.e., a running time like

*n*^{2}or*n*^{3}for inputs of*n*bits). Otherwise the problem is considered “hard”; often such hard problems take a running time that grows exponentially or nearly-exponentially with the input length*n*. The latter type of problem is not solvable in reasonable amounts of time for large input length.Under several idealizing assumptions that are approximately true in practice: quantum mechanics is the correct description of Nature; Alice’s lab and Bob’s lab is secure from the eavesdropper; their communication channel is “authenticated” (they know they’re talking to one another); and their apparatuses have low and benign errors.

If neither post-quantum nor quantum cryptography works, then as a last resort one can always put one’s secrets on a high-quality memory device detached from the internet and put this (or even a print-out) in a physical safe. However, this has many obvious disadvantages over computer-based cryptography.

In contrast, running Shor’s algorithm to break current cryptography would require thousands or even millions of qubits, depending on how error-free we can make these qubits and the operations upon them.

These ethical issues are not really specific to

*quantum*computers—they would apply also in case of much faster*classical*computers and/or much better*classical*algorithms. However, we expect the improvements in classical hardware to slow down (the end of Moore’s law is near), and we do not expect much faster classical algorithms for problems like factoring large numbers or simulating quantum systems.

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## Acknowledgements

Thanks to Joran van Apeldoorn, Harry Buhrman, and the anonymous referees for helpful comments that improved the presentation of this paper.

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de Wolf, R. The potential impact of quantum computers on society.
*Ethics Inf Technol* **19, **271–276 (2017). https://doi.org/10.1007/s10676-017-9439-z

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DOI: https://doi.org/10.1007/s10676-017-9439-z

### Keywords

- Quantum computing
- Societal impact
- Ethical impact