Researchers have shown that engineered quantum vacuum fluctuations can strengthen superconductivity, potentially offering a new way to control quantum materials and their collective behaviour directly.
Researchers at the Chinese Academy of Sciences used a terahertz split-ring resonator to engineer quantum vacuum fluctuations and strengthen the superconducting behaviour of niobium diselenide (NbSe₂), demonstrating a new way to influence quantum matter.
The international team found that the engineered vacuum could raise the material’s superconducting transition temperature by up to 5.4 per cent. The result represents what the researchers describe as the first experimental observation of vacuum-fluctuation-enhanced superconductivity.
The experiment tackles an unusual feature of quantum physics: even apparently empty space is not completely empty. At the quantum level, the vacuum contains unavoidable electromagnetic fluctuations. Researchers have now shown that these fluctuations can be manipulated sufficiently to affect the behaviour of a superconducting material.
To achieve this, the team placed a six-layer NbSe₂ device inside a specially designed terahertz split-ring resonator. The structure confines and reshapes electromagnetic fields, allowing the material to interact with the cavity’s fluctuating electromagnetic modes.
The researchers systematically altered the resonator’s geometry and electromagnetic environment, including its thickness and magnetic-field conditions. Measurements showed a noticeable change in the superconducting response, with the effect becoming particularly pronounced when the cavity’s characteristic energy matched the energy scale associated with low-energy superconducting fluctuations.
Theoretical modelling helped explain the observation. According to the researchers, the fluctuating electromagnetic field can interact with the superconducting state through virtual photons, lowering the energy of that state and making superconductivity more favourable.
The findings build on earlier work in which the team demonstrated direct control of vacuum fluctuations by switching the Casimir force between attraction and repulsion using a magnetic field.
Although the work remains experimental, it suggests that quantum vacuum fluctuations could become an engineered tool for manipulating superconducting materials. The researchers believe the approach may eventually contribute to efforts to control and improve the properties of quantum systems.
