Researchers have demonstrated for the first time that quantum vacuum fluctuations can enhance superconductivity, marking a significant advance in efforts to control quantum states of matter. The findings suggest that carefully engineered electromagnetic environments could provide a new way to influence superconducting materials without conventional external driving.
Although a vacuum may appear empty, quantum physics describes it as an environment filled with continuous fluctuations. Under the Heisenberg uncertainty principle, virtual particles can continually emerge and disappear, creating a dynamic “sea” of quantum activity.
Phenomena including the Lamb shift, spontaneous emission and the Casimir effect have provided experimental evidence for the existence of these vacuum fluctuations.
From Casimir Control to Superconductivity
The research was led by professors Zeng Changgan and Cheng Guanghui of the University of Science and Technology of China, part of the Chinese Academy of Sciences. The collaboration also included professor Jiang Qingdong of Shanghai Jiao Tong University, professor Frank Wilczek of the Massachusetts Institute of Technology and other researchers.
Zeng and Cheng’s team has previously investigated vacuum-fluctuation effects in condensed-matter systems. Earlier research demonstrated direct control over vacuum fluctuations by producing a reversible transition of the Casimir force from attraction to repulsion under a magnetic field.
That work raised a broader question: Could vacuum fluctuations also be harnessed to manipulate macroscopic quantum states?
Jiang’s team, meanwhile, has conducted theoretical studies into quantum-vacuum control of states of matter. The researchers proposed the concept of “vacuumronics,” in which engineered vacuum environments regulate electronic and photonic behaviour. That work provided a theoretical foundation for interpreting the superconductivity enhancement observed in the latest experiment.
Terahertz Cavity Amplifies Vacuum Fluctuations
“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.”
The researchers embedded the superconductor NbSe2 inside a terahertz dark cavity, creating a coupled superconductor–dark-cavity device.
By systematically comparing the material’s superconducting behaviour inside and outside the cavity, the team found a substantial increase in its critical temperature — the temperature below which the material enters a superconducting state.
“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. “This represents the first experimental observation of vacuum-fluctuation-enhanced superconductivity.”
Experiments Point to a Resonant Quantum Effect
To determine the source of the enhancement, researchers conducted control experiments involving several variables, including cavity geometry, characteristic frequency, material thickness, dielectric materials and metallic strips.
The experiments effectively ruled out conventional factors such as strain, material degradation, inhomogeneity and metallic screening effects.
The superconductivity enhancement also displayed a resonant, peak-like dependence on the characteristic frequency of the dark cavity.
“This result, closely tied to the cavity’s photonic properties, provides strong experimental evidence of the coupling between the superconducting state and dark-cavity modes,” Zeng said.
Virtual Photons Could Strengthen Superconductivity
Jiang’s team and Wilczek jointly developed a theoretical model to explain the underlying mechanism.
Using a Ginzburg–Landau framework, the researchers proposed that the superconducting state exchanges virtual photons with the dark cavity. This interaction lowers the energy of the superconducting state, thereby strengthening superconductivity.
“When the characteristic energy of the cavity mode matches the low-energy superconducting fluctuations, the NbSe2 device exhibits resonant enhancement, producing the peak in superconductivity enhancement,” Jiang said.
“In most practical physics, the vacuum serves merely as the passive stage on which phenomena play out. This work shows that the background itself can become an actor—engineered to strengthen superconductivity and reshape the behavior of quantum matter,” Wilczek said.
Noncontact Control of Quantum States
Unlike approaches that depend on continuous external stimulation, the experiment uses cavity-engineered vacuum fluctuations to enhance superconductivity without external driving.
The technique could provide researchers with a noncontact method of controlling quantum states of matter, potentially expanding the range of tools available for studying superconductors and other quantum materials.
“With further optimization of cavity structures and material systems, vacuum-fluctuation coupling may enable more pronounced and widely applicable control of quantum states,” Zeng said.
The demonstration represents an important step toward understanding how engineered quantum environments can alter the properties of matter. Further research will determine whether the approach can produce larger effects and be extended to a wider range of superconducting and quantum materials.
Nolan Fraser is a contributor at Angperyodiko.ca, covering a wide range of topics including news, politics, business, technology, sports, entertainment, and lifestyle. He focuses on delivering clear, accurate, and accessible reporting that helps readers stay informed about current events and developments that matter. With an emphasis on useful information and balanced storytelling, Nolan aims to provide timely coverage and relevant insights for audiences across Canada and beyond.