Targeted Shaking Stabilizes Exotic Quantum States

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.