Researchers led by Professors ZENG Changgan and CHENG Guanghui of China, along with collaborators at Shanghai Jiao Tong University and the Massachusetts Institute of Technology have for the first time experimentally demonstrated that quantum vacuum fluctuations can enhance superconductivity. The team embedded the superconductor NbSe2 within a terahertz dark cavity to amplify these fluctuations, observing a critical temperature increase of up to 5.4% in a six-layer device.
“Vacuum fluctuations in free space are generally too weak to produce observable effects in macroscopic condensed-matter systems,” said Professor ZENG, explaining how the dark cavity overcame this limitation and reshaped the electromagnetic environment. This finding confirms a theoretical framework proposed by Professor JIANG’s team.
Terahertz Dark Cavity Amplifies Vacuum Fluctuations
This amplification involved actively reshaping the electromagnetic environment to strengthen the impact on the material’s superconducting properties, rather than simply observing vacuum fluctuations. To accomplish this, researchers introduced a terahertz split-ring resonator, a structure designed to substantially amplify these normally imperceptible quantum effects, overcoming the inherent weakness of vacuum fluctuations in macroscopic systems. Professor ZENG explained that, “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 team then embedded the NbSe2 superconductor within this cavity, creating a coupled device where the superconducting state interacted with the amplified vacuum energy. Critical current and magnetic field strength also saw significant enhancement near the superconducting transition, indicating a clear improvement in the material’s performance. This resonant enhancement occurred when the cavity’s energy aligned with the low-energy fluctuations within the superconductor, maximizing the coupling effect.
This experimental demonstration moves beyond theoretical prediction, confirming a framework for the idea that engineered vacuum environments can actively regulate electronic and photonic behaviors. “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,” said Professor Wilczek. The researchers anticipate that further refinement of cavity designs and material choices will lead to even more pronounced control over quantum states, potentially opening new avenues for manipulating matter at its most fundamental level.
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.
Prof. Wilczek, Massachusetts Institute of Technology
NbSe 2 Superconductivity Enhanced by Cavity-Coupled Virtual Photons
This enhancement wasn’t simply a measurement of existing fluctuations, but a demonstration of actively reshaping the energy landscape around the superconducting material to bolster its properties. Professor ZENG explained that this result provides strong experimental evidence of the coupling between the superconducting state and the dark-cavity modes, a connection predicted by theoretical models developed by Professor JIANG’s team and Professor Wilczek. Their framework proposed that virtual photons exchanged between the superconducting state and the cavity lower the energy of the superconductor, effectively strengthening its ability to conduct electricity without resistance.
“When the characteristic energy of the cavity mode matched the low-energy superconducting fluctuations, the NbSe 2 device exhibited resonant enhancement, producing the peak in superconductivity enhancement,” said Professor JIANG, detailing the precise conditions for maximizing the effect. This experimental demonstration marks the first observation of vacuum-fluctuation-enhanced superconductivity, moving beyond theoretical prediction to a tangible result.
When the characteristic energy of the cavity mode matched the low-energy superconducting fluctuations, the NbSe 2 device exhibited resonant enhancement, producing the peak in superconductivity enhancement.
Prof. JIANG, Shanghai Jiao Tong University
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