The Emptiness That Enhances Superconductivity: How Quantum Vacuum Fluctuations Raised the Temperature of NbSe₂

In the usual sense, a vacuum is an emptiness where nothing exists. But in quantum physics, even "empty" space teems with virtual particles that are born and vanish, creating constant fluctuations. It is precisely these invisible oscillations that scientists have used for the first time to enhance the superconductivity of a material without direct contact or external influence.

Researchers from the University of Science and Technology of China placed an ultrathin niobium diselenide (NbSe₂) into a special "dark" cavity — a terahertz split-ring resonator. Such a design amplifies the quantum fluctuations of the electromagnetic field within the vacuum. As a result, the superconducting transition temperature rose by 5,4 % in a six-layer sample, and the critical current and critical magnetic field also increased noticeably.

Superconductivity arises when electrons form pairs and move without resistance at low temperatures. Usually, raising this temperature requires chemical additives, pressure, or strong magnetic fields. Here, however, the effect was achieved through the exchange of virtual photons between the material and the amplified vacuum of the cavity. The energy of the superconducting state is lowered, making it more stable.

The scientists conducted a series of control experiments, varying the cavity geometry, frequency, and materials to rule out ordinary causes such as mechanical strain or contamination. The enhancement manifested in a resonant manner — only when the cavity frequency matched the low-energy fluctuations of the superconductor. This confirmed the role of the quantum vacuum itself.

The discovery lays the foundation for a new approach — "vacuumronics" — in which a specially engineered emptiness becomes a tool for controlling quantum states. The method requires no direct energy input and can operate contactlessly, which is especially valuable for fragile nanostructures.

In the future, such cavities could help create more efficient superconductors for quantum computers, magnetic resonance imaging scanners, and energy-saving power transmission lines. The vacuum ceases to be a passive background and turns into an active participant in quantum processes.