Zener tunneling occurs when a charged particle, accelerated by an electric field, reaches a band crossing and tunnels from one band to another instead of following the adiabatic trajectory. In a semiconductor, this is interband tunneling — the electron jumps from the valence band to the conduction band, or vice versa, at the point in momentum space where the bands approach each other. The tunneling probability depends exponentially on the gap size and inversely on the electric field strength.
Paul and Refael (arXiv 2602.22328, February 2026) show that in van der Waals heterostructures — bilayers of two-dimensional materials stacked with weak interlayer coupling — the Zener tunneling process acquires interferometric structure. The carrier doesn't tunnel through a single gap. It encounters the hybridized band edge at multiple points as it accelerates through momentum space, and the tunneling amplitudes from different pathways interfere quantum mechanically.
The result is a solid-state interferometer built from the band structure itself. Two distinct signatures appear in the lateral conductance. First: Landau-Zener-Stückelberg oscillations periodic in 1/F (where F is the in-plane electric field), analogous to Shubnikov-de Haas oscillations but induced by the electric field rather than a magnetic field. The periodicity in 1/F arises because the phase accumulated between successive tunneling events depends on the area enclosed in momentum space, which scales as 1/F. Second: a resonance at a specific field strength F ∝ T₀^(3/2), where T₀ is the interlayer tunneling amplitude. This resonance is a direct probe of the interlayer coupling — measuring the resonance field gives the tunneling amplitude.
The physics maps onto a well-studied quantum optics problem — the Mach-Zehnder interferometer — but implemented in momentum space rather than real space. The band crossing plays the role of the beam splitter: it splits the carrier's quantum amplitude between two bands. The electric field plays the role of the path length: it determines the phase accumulated between successive splittings. The conductance oscillations are the interference fringes.
The proposal is specific to van der Waals heterostructures because the interlayer coupling is weak enough to produce a small gap (enabling Zener tunneling at accessible field strengths) but strong enough to produce measurable hybridization (creating the interferometric pathways). A monolayer has no interlayer gap; a strongly bonded bilayer has too large a gap for tunneling. The van der Waals coupling is in the window.
The conductance oscillations would be observable at cryogenic temperatures in standard transport measurements. No magnetic field required — the electric field does the work. The device is a field-effect transistor that happens to be a quantum interferometer.