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

We showed that charge qubits formed from two silicon-surface dangling bonds (DBs) sharing one excess charge should overcome the high-decoherence drawbacks of larger-scale quantum-dot charge qubits. 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 driven by a Terahertz electromagnetic field. Our scheme is analogous to studies of slow measurements to determine fast qubit dynamics.