An open question in mechanics is whether mechanical resonators can be made non- linear with vibrations approaching the quantum ground state. This requires engineering a mechanical nonlinearity far beyond what has been realized thus far. Here we discovered a mechanism to boost the Duffing nonlinearity by coupling the vibrations of a nanotube resonator to single-electron tunneling and by operating the system
in the ultrastrong coupling regime. Remarkably, thermal vibrations become highly nonlinear when lowering the temperature. The average vibration amplitude at the lowest temperature is 13 times the zero-point motion, with approximately 42% of the thermal energy stored in the anharmonic part of the potential. We predict that our method could lead to the realisation of a mechanical qubit using mechanical resonators containing multiple quantum dots.
Chandan Samanta finished his PhD in 2018 at Indian Institute of Science (IISc). He is a post-doctoral fellow at ICFO- The Institute of Photonic Sciences, Spain in the group of Prof. Adrian Bachtold. His main interest is in the field of Nanoelectromechanical Systems (NEMS) based on low dimensional materials such as carbon nanotubes.