Scientists Simulate Quantum Computing on a Traditional Computer

The simulation could be significant in determining how to build quantum computers.

Scientists at Linköping University have created a simulation of quantum computing that can be used on a traditional computer. The simulation, they say, shows how a quantum computer will really work.

The research team believes their work will help to progress quantum computing — a field of supercomputing that utilizes quantum-mechanical phenomena such as entanglement and superposition to perform computation.

RELATED: WHAT WILL QUANTUM COMPUTING CHANGE, EXACTLY?

Redefining supercomputers

The quantum computer is set to become a reality - a billion-dollar research effort in Sweden is aiming to release one within the next ten years. The EU has also designated quantum technology as one of its flagship projects.

It is expected that the technology will become incredibly important in simulations of biological, chemical, and physical systems that are too complex for even the most powerful supercomputers of today.

However, there is a lot that we don't yet know about how quantum computers will function.

Now, Professor Jan-Åke Larsson and his doctoral student Niklas Johansson, in the Division for Information Coding at the Department of Electrical Engineering, Linköping University, have provided a simulation that they say helps users to understand the functioning of a quantum computer and why it is more powerful than a classical computer.

"Our results should be highly significant in determining how to build quantum computers," Professor Jan-Åke Larsson said in a press release. The teams results have been published in the scientific journal Entropy.

"We have shown that the major difference is that quantum computers have two degrees of freedom for each bit. By simulating an additional degree of freedom in a classical computer, we can run some of the algorithms at the same speed as they would achieve in a quantum computer", says Jan-Åke Larsson.

The researchers' simulation tool is called Quantum Simulation Logic or QSL. The system simulates the operation of a quantum computer using a good old classical computer.

How it works

A bit, the smallest unit of data in a computer, can take only the value one or zero, but a quantum bit (a qubit) can take all values in between. Quantum computers, as such, don't need to process many operations for each calculation they carry out.

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The researchers' tool simulates this by allowing for one extra degree of freedom for each bit that is part of the processing calculation. 

"Each bit has two degrees of freedom: it can be compared with a mechanical system in which each part has two degrees of freedom - position and speed. In this case, we deal with computation bits - which carry information about the result of the function, and phase bits - which carry information about the structure of the function", Jan-Åke Larsson explains.

The scientists have already used QSL to study some quantum algorithms. Several of the algorithms, simulated in QSL, run as fast as they would in a quantum computer, the researchers claim.

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Scientists Simulate Quantum Computing on a Traditional Computer
Jan-Åke Larsson and his co-workers created a simulation for quantum computing. Source: Karl Ofverstrom

"The result shows that the higher speed in quantum computers comes from their ability to store, process and retrieve information in one additional information-carrying degree of freedom. This enables us to better understand how quantum computers work. Also, this knowledge should make it easier to build quantum computers, since we know which property is most important for the quantum computer to work as expected", says Jan-Åke Larsson.

The system shows great promise in helping students understand how quantum computing works.

For example, QSL can be used to understand quantum cryptography and quantum teleportation, as well as some computing algorithms, such as Shor's algorithm for factorization.

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What's more, a functioning simulation is a great tool for any researchers looking at ways that quantum computing will vastly change the computing landscape in the future.

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