  Detection of a single nuclear spin constitutes an outstanding problem in
different fields of physics such as quantum computing or magnetic imaging. Here
we show that the energy levels of a single nuclear spin can be measured by
means of inelastic electron tunneling spectroscopy (IETS).
  We consider two different systems, a magnetic adatom probed with STM and a
single Bi dopant in a Silicon nanotransistor. We find that the hyperfine
coupling opens new transport channels which can be resolved at experimentally
accessible temperatures. Our simulations evince that IETS yield information
about the occupation of the nuclear spin states, paving the way towards
transport-detected single nuclear spin resonance.
