QuTech Entangles Moving Electron-Spin Qubits, Teleports Quantum State

QuTech researchers have achieved a key advance for semiconductor-based quantum computing by successfully entangling electron-spin qubits while physically moving them on a chip. The team created a “conveyor belt” for qubits using traveling potential minima generated by gate electrodes, enabling the physical transport of these quantum bits across the chip’s surface. This capability was then used to teleport a quantum state a short distance, demonstrating a novel approach to connecting qubits and performing operations. “Qubits based on neutral atoms and trapped ions already had this functionality; now we can add spin qubits to the list,” says Maxim De Smet, first author of the paper and PhD candidate at QuTech, part of TU Delft. This innovation promises to ease scaling by reducing the complex control needed for qubit pairing and interconnection.

Electron-Spin Qubit Control via Traveling Potential Minima

Entangling electron spins while in motion represents a significant leap forward for semiconductor-based quantum computing, as researchers at QuTech have demonstrated a method of controlling qubits using traveling potential minima. Unlike previous demonstrations limited to neutral atoms and trapped ions, this achievement extends the capability to electron-spin qubits on a chip, paving the way for more scalable architectures. This novel approach isn’t simply about relocation; the motion itself becomes integral to quantum operations.

By precisely controlling the movement, researchers performed a two-qubit gate with the qubits while they were actively traveling, tuning the interaction by varying their separation. “We spent a lot of time making the conveyor smooth, without background potential disorder,” explains Maxim De Smet, a PhD candidate at QuTech, who led much of the experimental implementation. “Once the spin stays well confined in the moving quantum dot, you can use distance and timing as tunable parameters for the interaction, and you can trust what the readout is telling you.” This dynamic control offers a potential reduction in the complex pair-by-pair coupling needed to connect qubits in larger systems, easing the challenges of scaling. The demonstration extended to quantum state teleportation across a short distance on the chip, achieved by coordinating the movement of the qubits and precise timing of interactions.

Crucially, the readout process was also refined; the qubits are moved to fixed stations for measurement, avoiding the difficulty of directly measuring a moving spin. “A practical part of the achievement is that we can read out what happened without ever having to measure a moving spin directly,” says Yuta Matsumoto, a shared first author of the article. Lieven Vandersypen, chief scientist at QuTech and professor at TU Delft, highlights the broader implications: “What makes semiconductor qubits so compelling is the prospect of building complex quantum hardware with the same mindset that drove classical chips forward.”

Two-Qubit Gate Implementation with Dynamic Qubit Separation

The pursuit of scalable quantum computing increasingly focuses on architectures where qubits aren’t static entities, but rather dynamically connected and repositioned. Several platforms have demonstrated qubit mobility, and recent work from QuTech expands this capability to electron-spin qubits fabricated on a chip. This isn’t simply about relocating qubits, but integrating their movement into the computational process itself, opening avenues for more efficient processor designs. This approach allows for temporary coupling in dedicated interaction zones, followed by separation, reducing the need for complex, pair-by-pair control typically required in fixed-qubit architectures.

Crucially, the ability to precisely control the distance and timing of qubit interactions while in motion enables tunable gate operations. The team demonstrated this by bringing two qubits together, inducing an exchange interaction, and performing a two-qubit gate by varying their separation. “Error correction is not only about the fidelity of a single gate. It is also about connecting qubits, and how much routing you need for that,” adds Yuta Matsumoto, shared first author of the article, highlighting the potential for streamlined error correction schemes. The researchers emphasize that stable readout of the qubits, even while moving, was paramount to success; the qubits are transported to fixed readout stations, allowing for reliable measurement of their states. This work represents a step toward building larger, more versatile semiconductor-based quantum processors, mirroring the scalable fabrication techniques that underpin classical computing.

This innovative approach isn’t merely about repositioning qubits; the movement itself is integral to controlling quantum operations, opening new avenues for scaling spin-qubit processors. This gate relies on bringing two spins together in moving confining potentials, where an exchange interaction acts on them; the interaction is tunable by varying the qubit separation.

Source: https://qutech.nl/2026/05/07/the-qubit-there-and-back-again/