  In the present paper, we have proposed the experimentally achievable method
for the characterization of the collective states of qubits in a linear chain.
We study temporal dynamics of absorption of a single-photon pulse by three
interacting qubits embedded in a one-dimensional waveguide. Numerical
simulations were performed for a Gaussian-shaped pulse with different frequency
detunings and interaction parameters between qubits. The dynamic behavior of
the excitation probability for each qubit is investigated. It was shown that
the maximum probability amplitudes of excitation of qubits are reached when the
frequency of external excitation coincides with the frequency of excitation of
the a corresponding eigenstate of the system. In this case, the the magnitude
of the probability amplitude of each qubit in the chain unambiguously
correlates with the contribution of this qubit to the corresponding collective
state of the system, and the decay of these amplitudes are determined by the
resonance width arising from the interaction of the qubit with the photon field
of the waveguide. Therefore, we show that the pulsed harmonic probe can be used
for the characterization of the energies, widths, and the wavefunctions of the
collective states in a one-dimensional qubit chain.
