Researchers achieve movement of qubits in quantum dot chips

To advance quantum computing, we need large numbers of high-quality qubits that can be interconnected into error-corrected logical qubits. Some companies focus on manufacturing hardware, while others use atoms or photons, which offer greater flexibility for moving qubits.

Systems using atoms or ions can be moved around, allowing entanglement between any two qubits and facilitating error correction. In contrast, electronic-based systems are fixed during manufacturing, limiting their adaptability.

This week, a new paper published in Nature shows that quantum dots—tiny regions that trap a single electron—can be manufactured in bulk and used to host spin qubits. The research demonstrated that these spin qubits can be moved between quantum dots without losing their quantum state, combining mass production with the flexibility seen in atomic systems.

Quantum dots confine electrons in a small space, controlling their spin, which can be up or down. While electron-based qubits are fragile, quantum dots isolate them enough to perform well. Traditional chips lock the wiring during fabrication, which restricts the ability to change error correction schemes later.

The study, conducted by researchers at Delft University of Technology and QuTech, built a chip with a linear array of quantum dots. They started with electrons at each end and used electrical signals to shift the spins toward the center, enabling entanglement and two-qubit gates essential for quantum calculations.

Afterward, they moved the electrons back to their original positions, confirming that the quantum information remained intact. They also demonstrated quantum teleportation, moving the quantum state without physically relocating the object, with success rates of over 99% for gates and about 87% for teleportation.

These results suggest a future where qubits can be stored, moved, and entangled dynamically, similar to proposals for neutral atoms and trapped ions. This approach combines the benefits of bulk manufacturing and compact hardware, potentially overcoming current limitations.

Currently, the device had only six quantum dots, so practical application in complex systems is still distant. Quantum dots are less developed than transmons used by Google and IBM, but companies like Intel are working on improvements. It may take years before this technology rivals other qubit types in performance.

Ultimately, this research opens a promising path for scalable, flexible quantum hardware, with further advances likely in the coming years.