Effective quantum computers are still far away, but researchers are already showing more and more advantages these devices would bring to the table. A trio of theorists have shown one more talent of a quantum computer: it would be powerful enough to study the inner workings of the universe in ways that are far beyond the reach of even the most powerful conventional supercomputers.
Storing quantum information in atoms or using qubits is already a thing of the present, but quantum computers still require technologies that will likely be perfected in a few decades. The genius move here is building processors that rely on quantum mechanics instead of classical mechanics – these laws allow quantum switches to exist in both on and off simultaneous, thus being able to consider all the possible solutions at once.
Aside from bringing us some really cool and fast computers, it will also enable scientists to create some incredibly powerful quantum computers, which will be able to answer some of the biggest questions at the moment.
“We have this theoretical model of the quantum computer, and one of the big questions is, what physical processes that occur in nature can that model represent efficiently?” said Stephen Jordan, a theorist in NIST‘s Applied and Computational Mathematics Division. “Maybe particle collisions, maybe the early universe after the Big Bang? Can we use a quantum computer to simulate them and tell us what to expect?”
Questions such as this one involve keeping track of multiple elements and analyzing all their possible interactions, something which is just too much for today’s supercomputers. However, the team developed an algorithm that could run on any quantum computer, regardless of the specific technology which will be eventually used to build it. The algorithm would simulate all the possible interactions between two elementary particles colliding with each other, something that currently requires years of effort and a large accelerator to study.
Simulating these collisions is an enormously difficult problem for today’s digital computers because the quantum state of the colliding particles is very complex and, therefore, difficult to represent accurately with a feasible number of bits which only work with 0 and 1. The team’s algorithm, however, encodes the information that describes this quantum state far more efficiently using an array of quantum switches, making the computation far more reasonable.
“What’s nice about the simulation is that you can raise the complexity of the problem by increasing the energy of the particles and collisions, but the difficulty of solving the problem does not increase so fast that it becomes unmanageable,” Preskill says. “It means a quantum computer could handle it feasibly.”
Even though their algorithm showed only one type of collision, they believe their work paves the way for exploring the entire theoretical foundation on which fundamental physics rests.
“We believe this work could apply to the entire standard model of physics,” Jordan says. “It could allow quantum computers to serve as a sort of wind tunnel for testing ideas that often require accelerators today.”