Quantum breakthrough could speed up processing of large datasets

Breakthrough could boost applications of quantum technologies in AI, robotics and medical diagnostics

Researchers have demonstrated that a process known as quantum interference could accelerate the time it takes to process large datasets accurately.

Quantum interference is one of the most complex principles of quantum mechanics.

Broadly speaking, the concept states that particles, such as light photons, can experience interference – even if even there are no waves with which they can interfere.

In other words, a light photon can interfere with itself, thanks to another property of the quantum world – superposition – which states that an atom or subatomic particle can be located in more than one place at the same.

Interference has long been trumpeted as a mechanism that could allow a quantum computer to combine multiple calculations into one answer, but attempts to leverage the phenomenon in quantum computing have stagnated.

Now, scientists from the University of Warsaw, in collaboration with the University of Oxford and NIST, have applied quantum interference to speedily compute Kravchuk, an algorithm used to process low-fidelity data sets, such as those used in machine vision and autonomous vehicles.

Although Kravchuck is ideal for processing low-quality, noisy and distorted data, there is currently no fast algorithm that can compute the transform, severely limiting its practicality for real-world applications.

Using a setup designed to produced multiphoton quantum states, the researchers developed a specialised quantum computer capable of computing the transform.

In their article, published last week in Science Advances, researchers Dr. habil. Magdalena Stobinska and Dr. Adam Buraczewski describe how they used a quantum gate, which divides the photons between two outputs, to compute the transform.

“When two states of quantum light enter its input ports from two sides, they interfere. For example, two identical photons, which simultaneously enter this device, bunch into pairs and come out together by the same exit port. This is the well-known Hong-Ou-Mandel effect, which can also be extended to states made of many particles.

By interfering “packets” consisting of many indistinguishable photons (indistinguishability is very important as its absence destroys the quantum effect), which encode the information, one obtains a specialized quantum computer that computes the Kravchuk transform.”

The experiment was performed in a quantum optical laboratory at the University of Oxford, which leveraged specialised NIST sensors capable of counting photons, allowing the researchers to measure the quantum state leaving the beam splitter, that aligned with the result of the computation.

The researchers said their quantum computer always takes the same time to compute the transform, regardless of the size of the input data set, a feat they describe as the “Holy Grail” of computer science.

However, like every quantum computer, the computer needs to perform the experiment hundreds of times to get the results, but as the laser used produces millions of multiphoton “packets” per second, the process does not take long, the researchers added.

The University of Warsaw has applied for an international patent for the computer, which they note is still a proof of concept at this stage.