  In this paper, we design the first semiquantum private comparison (SQPC)
protocol which is realized via cavity quantum electrodynamics (QED) by making
use of the evolution law of atom. With the help of a semi-honest third party
(TP), the proposed protocol can compare the equality of private inputs from two
semiquantum parties who only have limited quantum capabilities. The proposed
protocol uses product states as initial quantum resource and employs none of
unitary operations, quantum entanglement swapping operation or delay lines.
Security proof turns out that it can defeat both the external attack and the
internal attack.
