Why quantum computers are more than powerful computers
by Tommaso Demarie, co-founder & CEO at Entropica Labs.
In his book “Homo Deus: A Brief History of Tomorrow”, Yuval Noah Harari predicts what projects will occupy humanity’s agenda during the next century and beyond. His rationale is the following: Thanks to improved scientific, societal, and political wisdom, humanity is getting closer to winning their battle against famine, plague, and war. But, he claims, history does not tolerate a vacuum. Once the efforts to eradicate these calamities are over, “what projects will replace them at the top of the human agenda in the twenty-first century?”.
His answer to the question is simple, yet the consequences are mind-boggling. The new human agenda will consist only of one project: attaining divinity. This includes defeating death, attaining endless happiness, and pushing our biological limits beyond what is conceivable today. To be clear, here I will not be talking about “the 10 things you should do to become a divine being”. My goal is rather to use a concept Harari states in his book, to make a point about quantum computing.
By trying to predict the consequences of our quest towards human gods, Harari realises that the implications posed by any new technology used to transform the biological features of humans, cannot be comprehended by people that only possess present-day capacities. He goes on to state, “people similar to us are likely to use biotechnology to re-engineer their own minds, and our present-day minds cannot grasp what might happen next”.
This concept can be extended beyond specific ideas about bodies and minds, and applied to history and progress as well: The intrinsic risk in predicting the future today, is that we are constrained to using the current scientific, moral, and political frameworks to describe a new paradigm that by definition exists beyond what those frameworks have the capacity to express.
As you might know by now (especially if you have been following my contributions to the Quantum World Association page on Medium), my background is in quantum information and computation. This is the branch of physics that describes how to store, process, and transmit quantum information. Quantum processors, i.e. machines that can — to different extents — perform all the above tasks, are commonly known as quantum computers.
Quantum computers are based on concepts so unfamiliar to our everyday experiences, that it is easy to fall for the temptation to think of them simply as “very powerful computers”. You might have heard researchers and experts say that we should think of quantum computers as specialised devices that bear the burden of solving certain computations that are too demanding for traditional, classical computers. In this simplified view, quantum computers are application-specific in the same way that GPUs or ASICs might be considered application-specific.
While this way of thinking helps to capture how quantum computers are likely to be used, it misses out on the fact that quantum computing is a completely new model of computation. Classical processors, be it the laptop I am using to write, your mobile phone, or HPCs on the cloud, exist in the realm of classical physics. Unlike them, quantum computers are governed by the rules of quantum mechanics. The most staggering consequence is that they can perform tasks believed to be practically impossible on classical computers.
Quantum computers were first proposed by the eccentric American physicist Richard Feynman and the Russian mathematician Yuri Manin, more than 30 years ago. Feynman and Manin understood that, since Nature is intrinsically quantum mechanical, any device apt to simulate the universe’s most fundamental processes must be quantum mechanical as well.
The idea of a computational model based on quantum systems reached global recognition in 1994. Peter Shor, then a researcher at Bell Labs, proved that any entity equipped with a powerful enough quantum computer could potentially break most commonly used cryptographic codes, including RSA — the padlock of all secrets on the internet.
Since Shor’s remarkable discovery, quantum computing shifted from being an academic oddity, to becoming one of the most exciting and active areas of research, with incalculable potential for savvy and lucky businesses. Today, more and more researchers (like me) move away from their university positions to create quantum startups aimed at accelerating the adoption of quantum computers by society. While the hype is at times unjustified, and some of the claims by the press plainly wrong, we all agree that the opportunities ahead are immense.
The intrinsic risk in predicting the future today, is that we are constrained to using the current scientific, moral, and political frameworks to describe a new paradigm that by definition exists beyond what those frameworks have the capacity to express.
Quantum computers use atoms and elementary particles as basic information carriers. They therefore have access to the full toolkit of quantum effects, which includes entanglement, superposition, and interference. The great intellectual challenge? To unleash the full potential of these tools, beyond solving our existing problems.
Indeed most, if not all, proposed use cases for quantum computers — and quantum technologies in general — are relics of our current way of thinking. Take quantum key distribution for example: It is an ingenuous protocol to securely transmit classical information that, unlike classical key distribution protocols, achieves unconditional security against any adversary: Nonetheless, the underlying task at hand is just a very elaborate phone call.
Quantum computers themselves promise to offer improved computing solutions for data analysis, AI & machine learning, hard optimisation problems, the simulation of complicated physical systems, chemical and biological processes. These, however, are all familiar problems to any scientist or engineer.
The most exciting aspect of the upcoming quantum revolution lies in the unknown. Just like imagining the feelings of a human with a transformed mind is a daunting challenge for us, we cannot grasp the full consequences of having access to a full-fledged quantum computer. The best we can manage at present, is to list all possible known applications that can benefit from quantum technologies.
To paraphrase the initial statement: The consequences posed by any new technology used to manipulate quantum information, cannot be fully comprehended by people that only possess a classical experience and understanding of the world. The early adopters of quantum computing technologies will be the first to experience the implications of the new paradigm, rather than only theorizing about them.
Of course, this is not the end of the story. As we improve the performance of the quantum devices, by learning better how to control the delicate quantum systems, we will discover novel uses that remain unthinkable today. There is more: I like to believe that by educating the next generation of software engineers and computer scientists about the wonders of the quantum world, we will dramatically increase the talent pool of people who can and will contribute to pushing our understanding of the universe to the new frontiers.
Today, just a handful of people are undertaking research in edge domains such as quantum gravity. Exposing the general public to quantum information and computation will sow the seeds for new ideas and point of views, some of which could be crucial to answering some of the hardest questions in physics.
So far, we used the promise of quantum computers to compete with classical computing, by creating better, quantum versions of existing algorithms. I hope that in the future, paraphrasing Harari, we might create ways to use quantum computers that “outstrip the ancient gods not in their tools, but in their bodily and mental faculties”.
If you liked this story and are interested in knowing more about our projects at Entropica Labs, write me at email@example.com
Thanks to Melissa John, Ewan Munro and Trond Linjordet for reading drafts of this.