For the first time, Chinese physicists have performed experimental demonstration of machine learning on a photonic quantum processor, showing that quantum computers are a promising replacement for conventional computers in the "age of big data".
A team of scientists at the University of Science and Technology of China has published a paper on the scientific journal Physical Review Letters. In the paper, they wrote that this demonstration "proved the suitability and potential power of quantum machine learning."
Machine learning, a branch of artificial intelligence, refers to the study of algorithms that empower a computer so it can learn from existing data and improve its performance.
Machine learning is now ubiquitous in fields like financial analysis, medical diagnosis, robotics, and computer science. Spam filters, for example, are often designed with machine learning algorithms.
Unfortunately, the creation of large amounts of electronic data in the past years has been challenging classical computing.
"It is estimated that every year it [electronic data] grows exponentially by 40 percent," Lu Chaoyang, one of the Chinese physicists, told Phys.org. "If it is to continue, then in about 2020, the chip size will shrink down to the atomic level where quantum mechanics rule. Thus, the speed-up of classical computation power faces a major challenge. Today, we may still be good running machine learning and other computational tasks with our good old classical computers, but we might need to think of other ways in the long run."
In 2013, Massachusetts Institute of Technology professor Seth Lloyd and his fellows published a paper which described the idea of quantum algorithms for machine learning, saying it would offer an exponential speed-up over traditional algorithms.
Such a speed-up is achievable thanks to the quantum state of superposition. In classical computing, a bit of data has a single value, either 1 or 0. But with quantum superposition, a quantum bit can represent 1 and 0 at the same time.
In that case, a single quantum object can perform a calculation on two numbers simultaneously; two quantum objects can handle 4 numbers, 3 objects for 8 numbers, 20 objects for over one million numbers.
With such an exponential speed-up, a computing task that will take a classical computer hundreds of thousands of years to complete, will only take a quantum computer about one second, according to Lu.
"The ability...on quantum computers, may provide a useful quantum toolkit for dealing with the 'big data'," the Chinese scientists concluded in their paper.