As the international pace for innovation continues towards large scale Quantum Computers, a recent announcement from China has demonstrated at 62 qubit programmable quantum computer. It is claimed that the computer uses the largest number of qubits built using superconducting technology currently in existance. The quantum computer is named Zu Chongzhi after the famous 5th century Chinese mathematician and astronomer.
Published in Science, the machine was built by a team at the University of Science and Technology of China (USTC). Science is one of the most highly respected peer review journals, which lends credence to the result. The scientists created an 8×8 matrix two dimensional qubit array with 62 functional qubits. Gates (both single and double qubit) were demonstrated and shown to be high fidelity. In addition a two dimensional quantum walk was demonstrated.
For those of a technical bent, you can see the paper “Quantum walks on a programmable two-dimensional 62-qubit superconducting processor” published by Science on the 6th of May 2021. This could be a big step forward for China which is rapidly expanding its Quantum Computing effort. Some of its major technology companies such as Baidu and Tencent have Quantum Computing programmes which like the American effort are aimed at making quantum computing as seamless as running on the conventional (classical) cloud computing.
Abstract of Quantum walks on a programmable two-dimensional 62-qubit superconducting processor
Quantum walks are the quantum mechanical analog of classical random walks and an extremely powerful tool in quantum simulations, quantum search algorithms, and even for universal quantum computing. In our work, we have designed and fabricated an 8×8 two-dimensional square superconducting qubit array composed of 62 functional qubits. We used this device to demonstrate high fidelity single and two particle quantum walks. Furthermore, with the high programmability of the quantum processor, we implemented a Mach-Zehnder interferometer where the quantum walker coherently traverses in two paths before interfering and exiting. By tuning the disorders on the evolution paths, we observed interference fringes with single and double walkers. Our work is an essential milestone in the field, brings future larger scale quantum applications closer to realization on these noisy intermediate-scale quantum processors. Read the full article.
The authors include: Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai Research Center for Quantum Sciences, NTT Basic Research Laboratories and Research Center for Theoretical Quantum Physics and National Institute of Informatics, Hitotsubashi, Chiyoda-ku, Tokyo.
The race with the Americans
There has been a slew of announcements from US or North American based companies on recent developments in Quantum Computing, often from some of the technology giants like Google and IBM and smaller Quantum start-ups such as Xanadu. Quantum Computing could be of national importance, as the technology could enable new applications and even kick-start an entire new industry as well affect national security. More qubits has often been the goal of many developers of Quantum Computers, but size isn’t everything. There are other parameters of importance when it comes down to accessing the development of Quantum Computers. IBM have developed their own measure of Quantum performance named Quantum Volume which aims to be a smarter indicator of performance beyond a simple measure of qubit count. We’ll see how this development stacks up against recent advances in time, but it is at least a welcome advancement that Quantum Computers might be ever more useful.