Studying Topological Superconductivity in vdW heterostructures enabled by robotically defined Planar Josephson Junctions

Topological superconductivity is promising platform for fault-tolerant quantum computation due to their ability to host Majorana zero modes, exotic quasiparticles that are their own antiparticles. These modes enable the encoding of quantum information in a non-local fashion, making the resulting qubits intrinsically robust against local sources of decoherence. A compelling approach to realize such states is through van der Waals (vdW) heterostructures, where a topological insulator (TI) is brought into proximity with a conventional superconductor (SC). This proximity effect induces Cooper pairing in the TI, potentially giving rise to topological superconductivity at the interface. To explore this regime, we demonstrate a novel device architecture: a planar Josephson junction fabricated using a robotically controlled technique. This method allows precise definition of sub-200 nm gaps between exfoliated superconducting flakes, creating an ultra-clean vdW junction. A TI flake is then deposited over this channel, forming a planar TI/SC/TI heterostructure. The resulting structure is not only well-suited to investigate Majorana bound states and phase-sensitive transport signatures such as the fractional Josephson effect but also provides a scalable pathway toward gate-tunable and phase-coherent topological qubit platforms.