**On measuring dangling-bond charge-qubit dynamics**

Recently we showed that charge qubits formed from two silicon-surface dangling bonds sharing one
excess charge should overcome the high-decoherence drawbacks of larger-scale quantum-dot
charge qubits [1]. However, decoherence of this charge qubit is speculative as the dynamics has not
yet been measured. Here we propose using an atomic force microscope to characterize the fast
tunneling rate and decoherence of the charge qubit. In our scheme the dynamics are studied by
observing frequency changes to an atomic force microscope cantilever. This cantilever is capacitively
coupled to the dangling-bond pair, which is being driven by a Terahertz electromagnetic field. Our
scheme is analogous to previous studies of slow measurements to determine fast qubit dynamics
[2,3].
[1] L. Livadaru et al., New Journal of Physics 12, 083018 (2010)
[2] J. R. Petta et al., Physical Review Letters 93, 186802 (2004)
[3] S. D. Barrett and T. M. Stace, Physical Review Letters 96, 017405 (2006)