Electron charge qubits on solid neon with 0.1 millisecond coherence time

Electron charge qubits built upon traditional semiconductors and superconductors are historically known to suffer from a short coherence time that hardly exceeds 10 microseconds. The primary source of decoherence comes from the inevitable charge noise in conventional host materials. However, electron charge qubits possess unparalleled advantages in their simplicities in design, fabrication, control, and readout. Here, we report our experimental realization of ultralong-coherence electron charge qubits based on a unique platform that we recently developed. The qubits utilize the motional states of isolated single electrons trapped on an ultraclean solid neon surface in vacuum and strongly coupled with microwave photons in an on-chip superconducting resonator. The measured relaxation time T₁ and coherence time T₂ are both on the order of 0.1 milliseconds. A single-shot readout fidelity of 97.5% without using a quantum-limited amplifier and a single-qubit gate fidelity of 99.95% using the Clifford-based randomized benchmarking are obtained. Simultaneous strong coupling of two qubits with the same resonator is demonstrated, as a first step toward two-qubit entangling gates for universal quantum computing. These results manifest that the electron-on-solid-neon (eNe) charge qubits have outperformed all the existing charge qubits to date and rivaled the state-of-the-art superconducting transmon qubits. The eNe qubit platform holds promise to become an ideal qubit platform and provides new insights toward scalable quantum computing architectures.