Research
Check out the most recent paper on three-site Kitaev chain featured in Nature Nanotechnology.
Figure 1. False coloured scanning electron microscope image of a 3-site Kitaev chain device. Credit:Alberto Bordin
Building Extended Quantum Chains for Robust Majorana States
Majorana zero modes (MZMs) are exotic quasiparticles widely regarded as key components for fault-tolerant quantum computing, thanks to their unique ability to protect quantum information from environmental noise. Despite their promise, reliably creating
and maintaining these elusive states remains a significant scientific and technological challenge.
Quantum Dots as Building Blocks for Majorana Platforms Our research is dedicated to constructing artificial systems designed to host stable Majorana zero modes. We utilize the Kitaev chain model—a theoretical representation of
a one-dimensional topological superconductor—as our blueprint. Experimentally, we implement this model by assembling chains of quantum dots, tiny semiconductor islands, embedded within indium antimonide (InSb) nanowires. These quantum dots are
interconnected precisely through superconducting aluminum (Al) segments, forming an engineered topological superconductor.
Enhancing Stability: The Advantage of Three Quantum Dots A critical research question is how the chain length influences the robustness of Majorana modes at its ends. Our recent experiments provide a direct comparison of stability
between minimal two-dot chains and extended three-dot chains, integrated side-by-side within the same nanowire device.
Our results clearly indicate that extending the chain from two to three quantum dots substantially enhances the stability of the resulting Majorana zero modes. Specifically, three-dot chains exhibit increased resistance to experimental imperfections,
notably variations in inter-dot coupling—an issue known to compromise simpler two-dot systems, often referred to as "poor man's Majoranas." Moreover, we observe improved resilience against fluctuations in individual quantum dot energy levels.
Figure 2: Visualization of a three-site Kitaev chain implemented with quantum dots in a semiconducting nanowire, showing the Majorana zero modes (orange) embedded in the end quantum dots.
A Step Toward Robust Quantum Computing Technology The implications of our findings are profound. Demonstrating increased stability through extended quantum chains represents a meaningful step toward scalable quantum computing
systems. By confirming that longer chains significantly improve Majorana stability, we identify a viable path to achieving the highly robust states necessary for practical quantum computation. Our work strongly motivates further exploration into
longer chains and more complex architectures, advancing the development of robust quantum technologies.
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