Prof. Johannes Knolle with his research colleague Prof. Hongzheng Zhao, who now works in China.
Photo Credit: Robert Reich / TUM
Scientific Frontline: Extended "At a Glance" Summary: Targeted Shaking Stabilizes Exotic Quantum States
The Core Concept: Researchers have developed a method using engineered, randomized multipolar driving—or "targeted shaking"—to drastically slow down unwanted heating in superconducting quantum processors, enabling the stabilization and observation of exotic quantum states.
Key Distinction/Mechanism: While conventional periodic "shaking" used to generate exotic quantum states typically causes the system to absorb energy, heat up, and rapidly lose its structure, this new approach relies on carefully designed patterns of random pulses. Because these randomized pulses partially cancel each other out over time, the system maintains its structural integrity, allowing researchers to track its evolution over more than a thousand driving cycles—a feat beyond the simulation capabilities of modern classical computers.
Major Frameworks/Components:
- Random Multipolar Driving: The application of mathematically designed random energy pulses (spectral engineering) that mitigate the thermal degradation of the system.
- 78-Qubit Processor: Experimental validation utilized the state-of-the-art "Chuang-tzu 2.0" superconducting quantum chip containing 78 quantum particles (qubits).
- Quantum Entanglement Tracking: Direct measurement of entanglement across the processor to monitor stability over an unprecedented 1,000+ driving cycles.
Branch of Science: Quantum Physics, Quantum Computing, and Condensed Matter Physics.
Future Application: This methodology provides a stable framework for advanced quantum simulation, allowing scientists to reliably construct and study entirely new, out-of-equilibrium states of matter. It also offers a viable pathway for extending operational coherence in future scalable quantum computing architectures.
Why It Matters: Uncontrolled heating and energy absorption have long stood as primary bottlenecks in the practical application of quantum simulators and computers. Proving that carefully engineered randomness can successfully control complex quantum systems and delay thermal breakdown overcomes a major hurdle in experimental quantum mechanics, bringing robust, real-world quantum computation one step closer to reality.
Exotic quantum states are highly sought after because they store and process information in fundamentally different ways than classical systems. To generate them, quantum systems are often periodically "shaken." In doing so, however, they typically absorb energy, heat up, and lose their structure - a major obstacle for quantum simulation and quantum computers. An international team of researchers has now succeeded in preventing this heating and creating stable, long-lived exotic states.
In a new study published in the journal Nature, the researchers show that unwanted heating can be drastically slowed down by randomly shaking a superconducting quantum computer with 78 qubits. Instead of adding energy through completely unstructured shaking, they use carefully designed patterns of random pulses that partially cancel each other out over time.
By directly measuring quantum entanglement in the processor, the team was able to track the system's evolution over more than a thousand driving cycles - far beyond what today's classical computers could simulate. The results show that even randomness, when carefully engineered, can be used to control complex quantum systems and explore new states of matter.
The quantum-theoretical predictions of the exotic systems now confirmed were developed during a research visit by then-doctoral student Hongzheng Zhao to the TUM School of Natural Sciences, where he worked with Prof. Johannes Knolle at his Professorship for Theory of Quantum Matter. Hongzheng Zhao has since become a professor at Peking University.
Experimental confirmation was achieved by a team led by Prof. Heng Fan at the Chinese Academy of Sciences, using a state-of-the-art "Chuang-tzu 2.0" quantum chip with 78 quantum particles (qubits). The Max Planck Institute for the Physics of Complex Systems in Dresden and Imperial College London were also involved in the research.
Published in journal:
- Nature
- Physical Review Letters (previous study)
Title:
- Prethermalization by random multipolar driving on a 78-qubit processor
- Random Multipolar Driving: Tunably Slow Heating through Spectral Engineering
Authors:
- Zheng-He Liu, Yu Liu, Gui-Han Liang, Cheng-Lin Deng, Keyang Chen, Yun-Hao Shi, Tian-Ming Li, Lv Zhang, Bing-Jie Chen, Cai-Ping Fang, Da’er Feng, Xu-Yang Gu, Yang He, Kaixuan Huang, Hao Li, Hao-Tian Liu, Li Li, Zheng-Yang Mei, Zhen-Yu Peng, Jia-Cheng Song, Ming-Chuan Wang, Shuai-Li Wang, Ziting Wang, Yongxi Xiao, Minke Xu, Yue-Shan Xu, Yu Yan, Yi-Han Yu, Wei-Ping Yuan, Jia-Chi Zhang, Jun-Jie Zhao, Kui Zhao, Si-Yun Zhou, Zheng-An Wang, Xiaohui Song, Ye Tian, Florian Mintert, Johannes Knolle, Roderich Moessner, Yu-Ran Zhang, Pan Zhang, Zhongcheng Xiang, Dongning Zheng, Kai Xu, Hongzheng Zhao, and Heng Fan
- Hongzheng Zhao, Florian Mintert, Roderich Moessner, and Johannes Knolle
Source/Credit: Technische Universität München
Reference Number: qs030926_01