D-Wave Systems Inc., the world's first commercial quantum computing company, today announced the publication of a peer-reviewed paper entitled "Thermally assisted quantum annealing of a 16-qubit problem" in the journal Nature Communications.
The paper presents the results of the first experimental exploration of the effect of thermal noise on quantum annealing. Quantum annealing is the process by which qubits, the basic unit of information in a quantum computer, are slowly tuned (annealed) from their superposition state (where they are 0 and 1 at the same time) into a classical state (where they are either 0 or 1). D-Wave quantum computers use this process to solve optimization problems in which many criteria need to be considered in order to come up with the best solution. These types of problems exist in many disciplines, such as cancer research, image recognition, software verification, financial analysis and logistics.
Using 16 qubits within a D-Wave processor, the experiments demonstrated that, for the problem studied, even with annealing times eight orders of magnitude longer than the predicted single-qubit decoherence time (the typical time it takes for environmental factors to start to corrupt the state of a qubit), the probabilities of performing a successful computation are similar to those expected for a fully coherent system. The experiments also demonstrated that by repeatedly annealing the open system quickly several times rather than annealing a hypothetical closed system slowly once, quantum annealing can take advantage of a thermal environment to achieve a speedup factor of up to 1,000 over the closed system (a closed system is one which does not interact with its environment, whereas an open system does interact with it).
"Our experiments demonstrated that mechanisms that many believed would disrupt quantum annealing (or AQC) calculations based on theoretical analyses of hypothetical, closed quantum systems operating at zero temperature don't necessarily do so for real, open quantum systems operating at finite temperature," said Eric Ladizinsky, co-founder and Chief Scientist of D-Wave. "One example of this, described in the paper, is that we found that a small amount of thermal noise (generally thought to be universally bad) can actually enhance problem solving effectiveness, rather than diminish it. As all real quantum computers will inevitably be open quantum systems operating at finite temperature we hope our paper will encourage others to think more deeply about the prospects of quantum computing in open quantum systems."
This paper is the latest in a long line of peer-reviewed papers from D-Wave scientists. Earlier this year, D-Wave published another paper in Scientific Reports, a Nature Publishing Group journal, discussing the effect of environmental decoherence on the ground state during adiabatic quantum computation. Over the past decade, almost 60 peer-reviewed papers authored by scientists at D-Wave have been published in prestigious journals, including Nature, Physical Review, Science, Quantum Information Processing, and the Journal of Computational Physics