Science 3 min read

New Chip Allows Two-dimensional Quantum Walks

"Random walks” is a mathematical model that describes a succession of random steps. But, classical mathematics is old news. There’s an equivalent to classical mathematics' random walks in quantum physics, called “quantum walks” that describe the motion in a superposition of positions.

Quantum walks, like random walks. | Peshkova | Shutterstock.com

Quantum walks, like random walks. | Peshkova | Shutterstock.com

Researchers built a 3D quantum chip that allows for 2D “quantum walks” with a single photon. This photonic chip could be used to boost existing analog quantum computing.

After a few aimless strolls through the park, a virtual trail of walking patterns are left behind. You might think that each step you took was random, on a whim, and never to be repeated.

Yet, there’s math to describe these “random” walks that can predict your next move.

In addition to computer science, and other fields like physics, economics, and chemistry, “random walks” is a mathematical model that describes a succession of random steps (the position of a walker) through a probability distribution of possible positions.

But, with the uptick in quantum study and the development of quantum systems, classical mathematics is old new.

Now, there’s an equivalent to classical mathematics’ random walks in quantum physics, called “quantum walks” that describe the motion in a superposition of positions.

Photonic 3D Chip to Boost Analog Quantum Computing

Scientists from two Chinese universities (University of Science and Technology and Shanghai Jiao Tong University) managed to build the biggest 3D quantum chip and successfully used it to demonstrated 2 quantum walks of a single photon.

Researchers used a technique known as Direct Femtosecond Laser Writing to build a large-scale 3D photonic chip that forms quantum walks on a 2D 49×49 grid.

Authors of the paper, published in Science Advances, explain:

“We demonstrate spatial two-dimensional quantum walks using heralded single photons and single photon–level imaging. We analyze the quantum transport properties via observing the ballistic evolution pattern and the variance profile, which agree well with simulation results. We further reveal the transient nature that is the unique feature for quantum walks of beyond one dimension. An architecture that allows a quantum walk to freely evolve in all directions and at a large scale, combining with defect and disorder control, may bring up powerful and versatile quantum walk machines for classically intractable problems.”

A performing 3D photonic chip that allows for 2D quantum walks could be used to power analog quantum computers, also known as quantum simulators until true quantum computers arrive.

A field that benefits from “quantum walks” models is AI (specifically deep neural networks) which has the ability and advantage to grow but in random way. Scientists could use 3D photonic chips to follow their growth and predict their development.

Would true quantum computers ever grace the market and make quantum simulators obsolete?

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Zayan Guedim

Trilingual poet, investigative journalist, and novelist. Zed loves tackling the big existential questions and all-things quantum.

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