Influence of Impurity Atom on the Width of Single Photon Superradiance in N Qubit System

We study the rate of superradiant emission for 1D N-qubit chain where N-1 qubits are identical and one impurity qubit has a different excitation frequency. It is shown that for relatively large frequency detuning between the impurity and other qubits in a chain, the impurity does not affect the width of superradiant emission for N-1 qubits. The transition from N qubit superradiant emission to that for N-1 qubits occurs in a narrow range of frequency detuning not exceeding one percent from the qubit excitation frequency.