Coherent manipulation of electron charge states on solid hydrogen

Condensed cryogenic substances of negative electron affinity support surface electronic states. They include noble-element liquid helium, solid neon, and non-noble-element solid hydrogen. Following our demonstration of long-coherence high-fidelity electron-on-solid-neon (eNe) charge qubits [1], we have extended our studies to solid hydrogen, which is known to have more favorable properties than neon. In this talk, we report the first demonstration of coherent manipulation of the electron charge (motional) states on solid hydrogen. The qubit states are controlled and read out via strong coupling of the electron to the microwave photons in a high-kinetic-inductance superconducting resonator. At the charge sweet spot, we measured a relaxation time T₁ = 32 us and a Ramsey coherence time T₂^*=9 us, showing a decent performance of an electron-on-solid-hydrogen (eH2) qubit.

[1] X. Zhou et al., “Single electrons on solid neon as a solid-state qubit platform,” Nature, vol. 605, no. 7908, pp. 46–50, May 2022, doi: 10.1038/s41586-022-04539-x.