June 2nd, 2012 by James Ayre
Quantum computers are still years away from becoming a reality, but a group of theorists has already developed an algorithm for them to simulate all the possible interactions when two elementary particles collide. Currently this type of research requires years of effort and massive, expensive particle accelerators.
Building quantum computers will require technology we currently don’t have, but they offer the possibility of vastly more powerful computing than even the largest supercomputers of today.
They work by having the switches in their processor take advantage of quantum mechanics, the laws that govern the interaction of subatomic particles. These laws allow the switches in quantum computers to be simultaneously on and off, allowing them to consider all possible solutions at once.
This ability is far beyond that of any current computers, and would enable them to solve extremely complex problems, such as breaking complex codes, and simulating particle collisions.
“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?”
Looking ahead to the development of a quantum computer, the theorists created an algorithm that will be able to run on any quantum computer, regardless of how it will be built, that can simulate particle collisions.
To do this with conventional computers would require an infeasible number of bits, but the algorithm developed by the theorists “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.”
“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.”
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