Towards a mechanical qubit in a carbon nanotube

Mechanical resonators based on carbon nanotubes are an exceptional platform to study the coupling between mechanical motion[1] and electron transport[2]. Recently, it has been shown that the second flexural mode of a carbon nanotube mechanical resonator may be coupled to a double quantum dot interdot transition[3]. In the ultra-strong coupling limit, the electron transition induces enough anharmonicity in the energy dispersion curve of the harmonic oscillator that the system can be used as a qubit[4].

In our work, we develop a reliable process to fabricate compact multi-electrode circuits that can sustain the harsh conditions of the nanotube growth. We measure high quality charge stability diagrams for double-quantum dots which may be coupled to the mechanical motion of the nanotube. We also discuss the read-out scheme for the future qubit.

[1] J. Moser et al., Nat. Nanotech. 9, 1007 (2014).

[2] W. Yang et al. PRL, 125, 187701 (2020)

[3] I. Khivrich, A. A. Clerk and S. Ilani, Nat. Nanotech., 14, 161-167 (2019).

[4] F. Pistolesi, et al., PRX 11, 031027 (2021)