How Big Does Your Quantum Computer Need To Be To Break Bitcoin Encryption or Simulate Molecules?

Advanced Quantum Computer Concept

Quantum computers are expected to be disruptive and potentially impact many industry sectors. So researchers in the United Kingdom and the Netherlands decided to explore two very different quantum problems: breaking the encryption of Bitcoin (a digital currency) and simulating the molecule responsible for biological nitrogen fixation.

In AVS Quantum Science, from AIP Publishing, the researchers describe a tool they created to determine how big a quantum computer needs to be to solve problems like these and how long it will take.

“The majority of existing work within this realm focuses on a particular hardware platform, superconducting devices, like those IBM and Google are working toward,” said Mark Webber, of the University of Sussex. “Different hardware platforms will vary greatly on key hardware specifications, such as the rate of operations and the quality of control on the qubits (quantum bits).”

Many of the most promising quantum advantage use cases will require an error-corrected quantum computer. Error correction enables running longer algorithms by compensating for inherent errors inside the quantum computer, but it comes at the cost of more physical qubits.

Pulling nitrogen out of the air to make ammonia for fertilizers is extremely energy-intensive, and improvements to the process could impact both world food scarcity and the climate crisis. Simulation of relevant molecules is currently beyond the abilities of even the world’s fastest supercomputers but should be within the reach of next-gen quantum computers.

Quantum Computer Blueprint With Trapped Ions

Quantum computer blueprint with trapped ions. Credit: Ion Quantum Technology Group, University of Sussex

“Our tool automates the calculation of the error-correction overhead as a function of key hardware specifications,” Webber said. “To make the quantum algorithm run faster, we can perform more operations in parallel by adding more physical qubits. We introduce extra qubits as needed to reach the desired runtime, which is critically dependent on the rate of operations at the physical hardware level.”

Most quantum computing hardware platforms are limited, because only qubits right next to each other can interact directly. In other platforms, such as some trapped ion designs, the qubits are not in fixed positions and can instead be physically moved around — meaning each qubit can interact directly with a wide set of other qubits. 

“We explored how to best take advantage of this ability to connect distant qubits, with the aim of solving problems in less time with fewer qubits,” said Webber. “We must continue to tailor the error-correction strategies to exploit the strengths of the underlying hardware, which may allow us to solve highly impactful problems with a smaller-size quantum computer than had previously been assumed.”

Quantum computers are exponentially more powerful at breaking many encryption techniques than classical computers. The world uses RSA encryption for most of its secure communication. RSA encryption and the one Bitcoin uses (elliptic curve digital signature algorithm) will one day be vulnerable to a quantum computing attack, but today, even the largest supercomputer could never pose a serious threat.

The researchers estimated the size a quantum computer needs to be to break the encryption of the Bitcoin network within the small window of time it would actually pose a threat to do so — in between its announcement and integration into the blockchain. The greater the fee paid on the transaction, the shorter this window will be, but it likely ranges from minutes to hours.

“State-of-the-art quantum computers today only have 50-100 qubits,” said Webber. “Our estimated requirement of 30 [million] to 300 million physical qubits suggests Bitcoin should be considered safe from a quantum attack for now, but devices of this size are generally considered achievable, and future advancements may bring the requirements down further.

“The Bitcoin network could perform a ‘hard-fork’ onto a quantum-secure encryption technique, but this may result in network scaling issues due to an increased memory requirement.”

The researchers emphasize the rate of improvement of both quantum algorithms and error-correction protocols.

“Four years ago, we estimated a trapped ion device would need a billion physical qubits to break RSA encryption, requiring a device with an area of 100-by-100 square meters,” said Webber. “Now, with improvements across the board, this could see a dramatic reduction to an area of just 2.5-by-2.5 square meters.”

A large-scale error-corrected quantum computer should be able to solve important problems classical computers cannot.

“Simulating molecules has applications for energy efficiency, batteries, improved catalysts, new materials, and the development of new medicines,” said Webber. “Further applications exist across the board — including for finance, big data analysis, fluid flow for airplane designs, and logistical optimizations.”

Reference: “The impact of hardware specifications on reaching quantum advantage in the fault tolerant regime” by Mark Webber, Vincent Elfving, Sebastian Weidt and Winfried K. Hensinger, 25 January 2022, AVS Quantum Science.
DOI: 10.1116/5.0073075

14 Comments on "How Big Does Your Quantum Computer Need To Be To Break Bitcoin Encryption or Simulate Molecules?"

  1. “improvements to the process could impact both world food scarcity and the climate crisis.”

    Wow, starvation and boiling oceans in one threatening phrase. But there is no food shortage, partly because CO2 has boosted food output by 20-30%. (Does an editor ever actually vet this stuff?) As for the “crisis aspect of climate change, that falls into the category of extraordinary popular delusions.

    But the Quantum Apocalypse. That is something that needs proactive management. Maybe even SEAL teams tasked with destroying such devices. Because the first country to achieve a useful quantum computer will be able to decrypt EVERYTHING. Imagine that.

  2. You are so willfully ignorant your brain is likely beyond repair.

    • What does an anonymous insult accomplish? You haven’t provided any factual or logical evidence that the things he said are false. Basically, all you are saying is that you think so highly of yourself that you feel evidence is unnecessary, and people should accept your pronouncements as being equivalent to stone tablets engraved by the finger of God. Unfortunately, even if you are someone to be highly respected, or even revered, being literally anonymous doesn’t give people a clue that they should bow down to you.

      • Someone smarter than you | January 31, 2022 at 9:36 pm | Reply

        Well richie hasn’t provided any factual or logical evidence that the things he said are true so… Kinda weird that you wouldn’t go after the one actually MAKING the baseless claims

  3. And right there in the article is the cheaper alternative to SEALs: quantum secure encryption. Already when we get them working, quantum computers won’t be able to decrypt squat.

  4. Well I certainly hope an editor vets Richie’s stuff (i.e. comment). Everyone is entitled to their opinion, but not everyone’s opinion is worth listening to or publishing.
    Statements like his, which differ so radically from what most people agree to be compelling evidence, and which he nevertheless seems to expect readers to believe simply because he says so, don’t deserve publishing IMHO.

  5. That’s not true. Just because you have a working quantum computer doesn’t mean you can immediately crack everyone passwords. By then we most likely already switched to quantum resistant systems

  6. I wonder how Richie functions without a brain.

  7. No one cares about breaking blockchain encryption. It is infinitely easier to just scam the users because transactions are effectively permanent and there is no regulation so scams are 100% legal. The worst thing that can happen is a wallet gets banned from an exchange, so just transfer all your crap to a new wallet.

  8. It isn’t the case that by providing quantum encryption methods we make the quantum decryption of classical encryption redundant. The widespread availability of quantum encryption is likely to lag far behind the niche (nation state) decryption of classical encryption. What’s more, there is plenty of encrypted traffic flowing today which is being harvested ready for later quantum decryption in the hope that the information is still useful by then.

  9. Everette Gould | February 6, 2022 at 1:52 am | Reply

    I would think that maybe we should have the computers working on the issue that is most pressing to humanity that absolutely no one seems to be talking about because right now there seems to be nothing we could ever imagine to do about it. What I’m referencing, of course, is the shifting of earth’s magnetic polarity due to occur in March of 2023. Obviously, we are incapable of stopping anything of this magnitude, but we need a solution to the sudden, abrupt loss of the protection from the harmful solar energy that our magnetosphere provides us. I mean, even with the best plan, in the best-case scenario, it’s going to be really, really horrifically tragic, trying and unlike anything humanity has ever faced. Just saying. What good is living underground when there’s nothing growing on the surface. I’m sure that it won’t take long for any survivors to become tired of only having their friends to eat. Sure, there will be plenty of corpses at first, but they’ll soon spoil and people will have to kill fresh meat every three days or so…. Meanwhile, all people care to do now is troll the internet and make petty arguments about Who is Right or wrong, when, seriously, everyone is so misinformed or miseducated that no matter what happens we could never form a cohesive, coherent team that could do anything more significant than kick a ball in the general direction of a predetermined area. I think we’ve all already lost.

  10. C’est bien d’entendre parler les ordi cantiques, mais on ne parle jamais les serveurs quantiques. A quoi de construire des voitures de gros cylindres de hyper horsepower puisque l’autoroute a de panneaux de vitesse limitée. Alors, il ne reste que la voie aérienne, mais le cerveau humaine ne pourrait non plus de supporter à certaines supersoniques allures.jusqu’a la liberté de vitesses, mais l’appareil non plus ne puisse supporter de telle propulsion car les matériaux construits ont aussi de ses atomes d’ébullition et des points de fusion.

  11. William J Olmstead | February 7, 2022 at 3:17 am | Reply

    all this because of greed that’s all it boils down to

  12. To those who think I made this up, here are a couple of things you could easily google.

    Quantum apocalypse, for example: https://www.newsweek.com/america-races-avert-quantum-apocalypse-1676366

    Food scarcity, for example: https://ourworldindata.org/food-supply
    CO2 and agriculture, for example: https://www.noaa.gov/news/study-global-plant-growth-surging-alongside-carbon-dioxide

    The climate non-crisis, for example: https://doi.org/10.1140/epjp/s13360-021-02243-9
    (A critical assessment of extreme events trends in times of global warming)

    There is plenty of scientific support for the contrarian point of view, if you are willing to look.

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