Two-dimensional superconductors have long been viewed as promising building blocks for next-generation quantum technologies, but their practical use has been limited by a stubborn materials problem: they are often extremely vulnerable to air. A team led by researchers including X. Zheng, S. Zaman and K. Zhang now reports a method that could remove one of the biggest barriers to their large-scale integration. In a study published in Nature, the researchers describe “encapsulation epitaxy,” a growth process that produces large-area, air-stable monolayer niobium diselenide, or NbSe₂, while simultaneously protecting it from the environment.
The material created in the study is only one atomic layer thick, yet it retains the electronic behavior needed for superconducting circuits. The films extend over areas larger than one inch, a scale that is unusual for high-quality two-dimensional superconductors. Unlike many exfoliated flakes, which are typically tiny and must be individually located and assembled, these films can potentially be incorporated into manufacturing processes that resemble wafer-scale device fabrication. That distinction could prove crucial if 2D superconductors are to move from laboratory demonstrations into practical quantum hardware.
The researchers’ approach relies on placing a protective two-dimensional material, such as graphene or hexagonal boron nitride, on a conventional three-dimensional substrate. The substrate can be made from materials including silicon dioxide or silicon nitride. During the growth process, this pre-deposited layer does more than shield the newly formed superconductor. It also acts as an atomic template, guiding niobium and selenium atoms to assemble into a continuous NbSe₂ sheet at the hidden interface between the encapsulation layer and the substrate.
This is the central idea behind encapsulation epitaxy. In conventional epitaxial growth, a crystalline substrate guides the arrangement of atoms in a newly deposited film. Here, the encapsulating 2D layer performs a dual function: it provides a chemically protected growth environment and helps determine how the superconducting film forms. Because the NbSe₂ develops underneath the graphene or hexagonal boron nitride, the resulting structure is shielded from oxygen and moisture almost immediately. The method therefore addresses both the synthesis and stability challenges that have made monolayer superconductors difficult to handle.
Niobium diselenide is especially attractive because it supports more than one form of collective quantum behavior. At low temperatures, it becomes superconducting, allowing electrical current to flow without resistance. The reported graphene/NbSe₂ heterostructures display a superconducting transition temperature of approximately 1 kelvin. Although that temperature is far below everyday conditions, it is compatible with the operating environments of many superconducting quantum circuits, which are cooled to extremely low temperatures to suppress thermal noise and preserve quantum states.
The films also show a pronounced charge-density wave, or CDW, with a transition temperature of about 177 kelvin. A CDW is an organized modulation of electron density that is coupled to a periodic distortion of the crystal lattice. In NbSe₂, superconductivity and charge-density-wave order emerge from the same electronic system, making the material valuable for studying how competing and cooperating quantum phases interact. The enhanced CDW response observed in the encapsulated films suggests that the interface and growth conditions may significantly influence the material’s electronic properties rather than simply preserving those of a freestanding flake.
The team then addressed another challenge: connecting an atomically thin superconductor to the outside world without exposing it to oxygen. They developed oxidation-free transfer procedures and superconducting edge-contact techniques that allow the encapsulated NbSe₂ to be integrated into circuit structures. Edge contacts are important because conventional top contacts can introduce barriers or damage delicate interfaces. By contacting the exposed edge of the monolayer, engineers can create a more direct electrical connection while keeping the active surface protected.
One of the most significant measurements concerns kinetic inductance. In a superconductor, current is carried by paired electrons, but the inertia associated with those pairs contributes an inductive response. This effect, called kinetic inductance, becomes especially important in ultrathin materials because the current is confined to a very small volume. The researchers measured a kinetic inductance of approximately 0.7 nanohenries per square in the monolayer NbSe₂. A high kinetic inductance allows engineers to build compact inductors and resonators using much less physical area, a major advantage for densely packed superconducting circuits.
That capability could open new routes for miniaturized resonators, filters, detectors and other circuit elements used in quantum information systems. Two-dimensional materials offer atomically flat interfaces and exceptional thickness control, while graphene and hexagonal boron nitride can serve as conductive, insulating or protective components within van der Waals heterostructures. Combining these materials with a superconducting monolayer may allow circuit designers to tailor electrical, mechanical and dielectric properties at the scale of individual atomic layers.
The study does not eliminate every challenge facing 2D superconducting technology. Quantum circuits still require extremely low temperatures, precise fabrication and careful control of disorder and interfaces. Researchers will also need to establish how consistently the films can be produced across full wafers and determine whether their superconducting properties remain uniform in increasingly complex devices. Even so, the reported method offers a striking solution to the air-sensitivity problem. By turning encapsulation into part of the growth process itself, the work points toward large-area, protected superconducting films that could eventually be incorporated into monolithic quantum circuitry. The result is a rare combination of materials science and device engineering: a one-atom-thick superconductor that is not only functional, but also designed from the beginning to survive the journey from synthesis to circuit.
Subject of Research: Encapsulation epitaxy and the integration of air-stable monolayer niobium diselenide superconductors into quantum circuits.
Article Title: Encapsulation epitaxy of air-stable 2D superconductors for quantum circuits
Article References: Zheng, X., Zaman, S., Zhang, K. et al. “Encapsulation epitaxy of air-stable 2D superconductors for quantum circuits.” Nature (2026). https://doi.org/10.1038/s41586-026-10865-1
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41586-026-10865-1
Keywords: two-dimensional superconductors, niobium diselenide, NbSe₂, encapsulation epitaxy, graphene, hexagonal boron nitride, quantum circuits, kinetic inductance, charge-density waves, superconductivity, van der Waals materials, monolayer materials
