Single electron qubit on solid neon

Team demonstrates a fundamentally new type of qubit based on single electrons trapped on solid neon surface with ultralong quantum coherence times of ~0.1 ms, establishing a new promising platform for universal quantum computing.

A new qubit platform: Single electron qubits (blue and green balls) on solid neon (transparent slabs) with ultralong coherence time are trapped and controlled by superconducting quantum circuits (bottom patterned chip).

Quantum bits (qubits) are the fundamental building blocks in quantum computers and many other quantum technologies. An ideal qubit platform would simultaneously embody long coherence, fast operation, high fidelity, and large scalability.

Scientists at the Center for Nanoscale Materials at Argonne recently made substantial advances towards such an ideal qubit platform by developing a fundamentally new type of qubit based on single electrons trapped on a solid neon surface [1, 2]. Solid neon, a noble-gas element, provides an ultraclean substrate for hosting the electron qubits with no uncontrollable impurities or electromagnetic noise. This novel scheme allows the team to significantly extend the coherence time of the charge state of singe electron qubits to ~0.1 ms – nearly a thousand times better than the previous record.

The electron-on-solid-neon (eNe) qubit device incorporates the state-of-the-art circuit quantum electrodynamics (cQED) architecture for quantum state control and readout. By integrating an electron trap in a superconducting quantum circuit, strong coupling between the motional states of a single electron and a single microwave cavity photon is achieved, permitting coherent energy exchange between the two-level qubit system and the single-photon state in the cavity.

After their first demonstration of the eNe qubit [1], the research team recently made further breakthroughs in achieving record long coherence time via Ne annealing, trapping potential stabilization, and the charge-noise-insensitive (sweet) spot qubit operations. The measured energy relaxation time (T₁) and coherence time (T₂) are both on the order of 0.1 ms [2], surpassing all existing charge qubits and rivalling state-of-the-art superconducting transmon qubits. High-fidelity single qubit gates (>99.97%) and high-fidelity single-shot readout (>98.1%) are also demonstrated.

The team is now working on two-qubit entanglement and gates, as well as schemes to manipulate the spin state of eNe qubits, which is predicted to have a longer coherence time of ~80 seconds [3]. This work represents a major milestone achieved in new quantum computing architectures. The single-electron-on-neon qubit platform also opens new avenues for quantum sensing and other quantum technologies.

References:

[1] X. Zhou, G. Koolstra, X. Zhang, G. Yang, X. Han, B. Dizdar, X. Li, R. Divan, W. Guo, K. W. Murch, D. I. Schuster, and D. Jin, Single electrons on solid neon as a solid-state qubit platform, Nature 605, 46 (2022).

2] X. Zhou, X. Li, Q. Chen, G. Koolstra, G. Yang, B. Dizdar, Y. Huang, C. S. Wang, X. Han, X. Zhang, D. I. Schuster, and D. Jin, Electron charge qubits with 0.1 millisecond coherence time, Nature Physics 20, 116 (2024).

[3] Q. Chen, I. Martin, L. Jiang, and D. Jin, Electron spin coherence on a solid neon surface, Quantum Science and Technology 7, 045016 (2022).