Evidence for vacuum-enhanced superconductivity in NbSe₂

Vacuum fluctuations provide an important new way to control material properties non-invasively^1-6. Here we present experimental evidence that they can enhance superconductivity. NbSe₂ is a layered transition-metal dichalcogenide with well-characterized superconducting behaviour, providing a clear platform to reveal this effect. We have observed an increase in the critical temperature of superconducting NbSe₂ when it is embedded in a split-ring cavity resonator. Near the transition temperature, the critical current and critical field increase notably. Our observations are consistent with theoretical calculations showing that hybridization between electronic degrees of freedom and fluctuating cavity modes lowers the energy of the superconducting state. By providing a proof-of-principle demonstration of superconductivity enhancement through vacuum fluctuations, our work establishes a non-invasive technique for controlling the mainstay of quantum technology.