Waveguide transport mediated by strong coupling with atoms

Abstract

We investigate single photon scattering properties in one-dimensional waveguide coupled to quantum emitter's chain with dipole-dipole interaction (DDI). The photon transport is extremely sensitive to the location of the evanescently coupled emitters. The analytical expressions of reflection and transmission amplitudes for the chain containing two emitters with DDI are deduced by using real-space Hamiltonian. Two cases, where the two emitters symmetrically and asymmetrically couple to the waveguide, are discussed in detail. It shows that the reflection and transmission typical spectra split into two peaks due to the DDI. The Fano minimum in the spectra can also be used to estimate the strength of the DDI. Furthermore, the DDI makes spectra strongly asymmetric and create a transmission window in the region where there was zero transmission. The scattering spectra for the chain consisting of multi-emitters are also given. Our key finding is that DDI can broaden the frequency band width for high reflection when the chain consists of many emitters

Influence of the nonradiative decay of qubits into a common channel on the transport properties of microwave photons

“…Neglecting the quantities A, B and C, in the expressions (18), (20) and (21) we obtain for the coefficients t and r the expressions which exactly coincide with those already known (expressions (11a) and (11b) in the work [6]). …”

“…The calculations were carried out for identical qubits: Fig. 2 it is clearly seen that in the region J < 2Γ 1 the expression (20) leads to the results that substantially differ from those which follow from the expression (11a) in [6]. Even more clearly this difference is evident in Fig.…”

“…2 and Fig. 3 the transmission |t| calculated from (20) is compared with the one calculated from the expression (11a) in [6]). The calculations were carried out for identical qubits: Fig.…”

“…Off-diagonal elements in the matrix (6), in addition to the direct interactions J describe an indirect interaction √ Γ 1 Γ 2 e ikd due to spontaneous radiation of the excited qubits, and the interaction √ γ 1 γ 2 /2, caused by nonradiative decay into a common channel. We note that the contribution of spontaneous emission depends on the frequency of the scattered photon ω (k = ω/v g ).…”

“…From the formal point of view, it corresponds to the addition to the qubit excitation frequency Ω of the imaginary quantity −iγ, where γ is the decay rate of the excited state of a qubit into a nonradiative channel [3][4][5][6]. It seems to be reasonable for one qubit in a waveguide.…”