Probing a single dipolar interaction between a pair of two-level quantum system by scatterings of single photons in an aside waveguide

• Single photons transport in one dimension waveguide and couple with two qubit with dipolar interaction.
• The transmission spectra of the waveguide photons will be changed by the dipolar interaction.
• The dipolar interaction strength will be read by the detuning.
• The phase shift also influences the transmission spectra.

Weak dipolar interactions exist widely in various atomic, nuclear and molecular systems, and could be utilized to implement the desired quantum information processings. However, these interactions are relatively weak and hard to be measured precisely. Here, we propose an approach to detect such a weak interaction by probing the transport of a single waveguide-photon scattered by two aside qubits with a single dipolar exchange-interaction. By a full quantum theory of photon transports in optical waveguide, we show that the dipolar interaction between the aside two qubits significantly influence the transmitted spectra of the photon traveling along the one-dimensional waveguide. Thus, probing the relevant changes in the transmitted spectra and the transmission probability distribution specifically for the resonant photons, compared with those scattered by the two individual qubits, the information of the single dipolar interaction between the qubits could be extracted. The feasibility of the proposal is also discussed.