This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In a study published in Nature on Aug. 19, a research team has enhanced superconductivity through vacuum fluctuations for the first time. The achievement marks a significant advance in controlling quantum states of matter.
Space free of matter is not truly empty. In quantum electrodynamics, the Heisenberg uncertainty principle implies that, even in the ground state, there is irreducible activity, with the continual creation and annihilation of virtual particles. Thus, a vacuum contains a dynamic "sea" of quantum fluctuations.
Several celebrated phenomena, including the Lamb shift, spontaneous emission and the Casimir effect, provide compelling experimental evidence for their existence. The research was led by professors Zeng Changgan and Cheng Guanghui of the University of Science and Technology of China of the Chinese Academy of Sciences and including professor Jiang Qingdong of Shanghai Jiao Tong University, professor Frank Wilczek of the Massachusetts Institute of Technology and other collaborators. In recent years, Zeng and Cheng's team has focused on vacuum-fluctuation effects in condensed-matter systems.
In an earlier study, the team achieved direct control over vacuum fluctuations: a reversible transition of the Casimir force from attraction to repulsion under a magnetic field. The study inspired a further question: Can vacuum fluctuations be harnessed to manipulate macroscopic quantum states? Besides these experimental efforts, Jiang's team has conducted theoretical studies of quantum-vacuum control of states of matter.
The team proposed the concept of "vacuumronics," in which engineered vacuum environments regulate electronic and photonic behaviors, thereby laying the theoretical foundation for interpreting the mechanism of vacuum-enhanced superconductivity reported in this study. "Vacuum fluctuations in free space are generally too weak to produce observable effects in macroscopic condensed-matter systems," Zeng said. "To overcome this limitation, we introduced a terahertz split-ring resonator.
Such a dark cavity can reshape the electromagnetic environment and substantially amplify vacuum fluctuations." In this study, Zeng and Cheng's team embedded the superconductor NbSe2 in the terahertz dark cavity, constructing a superconductor–dark-cavity coupled device. By systematically comparing superconductivity outside and inside the cavity, the team found a substantial increase in the superconducting critical temperature of NbSe2. "We observed that the critical temperature can increase by up to 5.4% in a six-layer NbSe2 device, while the critical current and critical magnetic field are significantly enhanced near the superconducting transition," Cheng said.
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