A group of researchers from universities in Australia and the United States, in collaboration with quantum technology company BTQ, recently published a study proposing a new proof-of-work (PoW) scheme for blockchain consensus that relies on quantum computing technology to verify consensus.
The preprint research paper, called "Consensus Proof of Work by Quantum Sampling," details a system that the authors claim is "significantly faster and more energy efficient compared to classical hardware computation.
According to the researchers, current algorithms for solving the PoW consensus puzzle are slow and require significant computational resources to process: "While classical PoW schemes like Bitcoin are notoriously energy-inefficient, our PoW scheme based on boson sampling allows for a more energy-efficient alternative in quantum hardware implementations. "
The quantum advantage offered by this scheme also makes mining more difficult, so that as the number of miners increases, it becomes possible to "maintain consistent block mining times," further incentivizing the continued participation of "quantum miners," according to the paper.
The sampling process mentioned by the researchers, boson sampling, is not a completely new idea, but its application in blockchain technology seems to be innovative. Boson sampling has shown promise in numerous quantum computing applications. Nevertheless, as a non-generic quantum computing solution (it must be used for systems built for specific tasks), its potential is limited to a few fields, such as chemistry.
However, according to the researchers, it could be the perfect solution for future-oriented blockchain applications and has the potential to reduce the environmental impact of mining on the Bitcoin blockchain and similar blockchains.
In addition to quantum advantages, quantum hardware has advantages on older computers due to the nature of blockchain mining efforts.
Currently, one of the advantages that classical supercomputers have over newer quantum computers is the ability to "precompute" when working on the same class of problems on a regular basis. But when it comes to the blockchain, such precomputing is largely wasted.
As the researchers put it, mining is a "no progress" problem. No matter how many times the blockchain puzzle is solved to provide proof of workload, the challenges posed by computer and algorithmic processing will never get better.
This means that quantum computers, while challenging to develop and expensive to build and maintain, will ultimately be able to verify consensus more effectively than the most advanced classical systems.