A Shanghai Jiao Tong University research team has developed the world’s largest-scaled 3D photonic quantum chip that can demonstrate a 2D quantum walk. Their study “Experimental Two-dimensional Quantum Walk on a Photonic Chip” has been published on the open-access scientific journal Science Advances, and is regarded as a huge boost to quantum simulation.

Quantum computing’s promise of greatly improved speed compared to binary-based classical computing has tech giants such as Intel, Google, Microsoft and Alibaba scrambling to develop their own quantum computers. While a general purpose quantum computer remains a long way off, researchers are putting efforts in quantum simulation — a system of quantum bits designed to simulate specific problems or solve for a particular equation faster than the fastest classical computer.

Quantum walks is the quantum equivalent of the classical random walks process, but with superpositions. Quantum walks shows superior performance over classical counterparts in quantum searching and quantum simulation applications. Quantum walks can be expanded by enlarging the dimensions of the evolution network. Previously, most experimental quantum work was in one dimension.

The SJTU research team used a technique called femtosecond laser direct writing to construct a three-dimensional photonic chip with up to 49X49 nodes, the world’s largest-scale chip ever. The team successfully demonstrated a 2D continuous-time quantum walk in real spatial space with the chip. This will facilitate the realization of quantum algorithms based on quantum walks, and the exploration of more quantum computing tasks in the future.

The research team was led by Xianmin Jin, who has been working on advanced quantum integration techniques at the Department of Physics at University of Oxford since 2010. In 2014, Jin returned to China and established the Laboratory of Integrated Photonics and Quantum Information at SJTU. The lab focuses on multilayer quantum integration and has made significant breakthroughs in the field of quantum chips after years of efforts. Jin’s is one of few research teams with both a quantum information research background and quantum chip making capabilities.

Xianmin Jin’s team presents an alternative method for enlarging the scale of quantum states space by increasing the external physics dimension and complexity of the quantum evolution system. Moreover, they have developed greater feasibility in quantum experiments which is of great significance for the future research of quantum computer simulation.

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Author: Jessie Geng| Editor: Tony Peng, Michael Sarazen

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