An international research team has reported the first experimental evidence that quantum fluctuations in a vacuum can enhance superconductivity, according to findings published in Nature. The collaboration involved researchers from the University of Science and Technology of China, Shanghai Jiao Tong University, and the Massachusetts Institute of Technology.
According to quantum physics principles, a vacuum is not truly empty space. Quantum electrodynamics and the Heisenberg uncertainty principle describe a lowest energy state that is never perfectly still, with virtual particles continuously appearing and disappearing to create a constant background of quantum fluctuations. These fluctuations have been observed through established phenomena including the Lamb shift, spontaneous emission, and the Casimir effect. The research teams investigated whether these vacuum fluctuations could be used to control macroscopic quantum states, building on earlier work demonstrating manipulation of the Casimir force using magnetic fields.
The researchers introduced the concept of “vacuumronics,” in which specially designed vacuum environments control electronic and photonic behavior. To test their theory, they placed the superconductor NbSe2 inside a terahertz dark cavity that reshaped the electromagnetic environment and amplified vacuum fluctuations. Comparisons of the material’s behavior inside and outside the cavity revealed that placement in the cavity increased the superconducting critical temperature—the threshold below which the material becomes superconducting—by up to 5.4% in a six-layer NbSe2 device. The critical current and critical magnetic field also showed significant enhancement near the superconducting transition.
Control experiments varying cavity geometry, frequency, material thickness, and other parameters ruled out conventional explanations such as strain or material degradation. A key finding was the resonance-like peak in superconductivity enhancement at particular frequencies, strongly suggesting coupling between the superconducting state and the cavity’s photonic properties. The theoretical framework developed to explain the effect proposes that the superconducting state exchanges virtual photons with the dark cavity, lowering the superconducting state’s energy and strengthening the effect.
The research suggests that engineered vacuum environments could become a new control mechanism for superconductors and other quantum materials without requiring direct external energy input. Researchers indicated that further optimization of cavity structures and material systems may enable more pronounced and widely applicable control of quantum states through vacuum-fluctuation coupling.
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