Toward flying qubit spectroscopy.

While the coherent control of two level quantum systems -qubits- is now standard, their continuum electronic equivalents -flying qubits- are much less developed. A first step in this direction has been achieved in DC interferometry experiments. Here, we propose a simple setup to perform the second step, the spectroscopy of these flying qubits, by measuring the DC response to a high frequency AC voltage drive. Using three different concurring approaches -a simple Floquet theory, a semi-analytical approach and time dependent simulations of a microscopic model- in a multi-terminal geometry, we predict the power-frequency map of the device. We argue that this spectroscopy provides a direct measurement of the flying qubit characteristic frequencies and a key validation for more advanced quantum manipulations.