Tunable one-dimensional microwave emissions from cyclic-transition three-level artificial atoms

By strongly driving a cyclic-transition three-level artificial atom, demonstrated by such as a flux-based superconducting circuit, we show that coherent microwave signals can be excited along a coupled one-dimensional transmission line. Typically, the intensity of the generated microwave is tunable via properly adjusting the Rabi frequencies of the applied strong-driving fields or introducing a probe field with the same frequency. In practice, the system proposed here could work as an on-chip quantum device with controllable atom-photon interaction to implement a total-reflecting mirror or switch for the propagating probe field.

Figure 1

Circuit diagram [10] of an artificial atom (generated by four-junction flux qubit geometry) inductively coupled to a 1D long transmission line.

Figure 2

Schematics of the driven three-level artificial atom: (a) Strong fields with Rabi frequencies ${\Omega }_{31}$ and ${\Omega }_{32}$ are applied to produce microwave emission between the levels $|1\rangle$ and $|2\rangle$. (b) A weak probe field with Rabi frequency ${\Omega }_{21}$ is additionally applied to control the microwave emission.

Figure 3

(a) The microwave emission spectrum induced by strong driving fields ${\Omega }_{31}$ and ${\Omega }_{32}$. (b) The intensity of produced microwave current as a function of $\Omega$ ($\left|{\Omega }_{31}\right|=\left|{\Omega }_{32}\right|=\Omega$) at $\Delta =0$.

Figure 4

Switch-off the produced microwave emission by a probe field. (a) Induced microwave emission spectrum without control probe (dashed line), which can be switched off at resonant point by a control probe ${\Omega }_{21}$ (solid line). (b) The intensity plot displays the optimal working point for the probe to switch off the microwave emission: $\Theta =\pi /2$, $\left|{\Omega }_{21}\right|/2\pi =1.78$ MHz.

Figure 5

(a) When no driving fields applied, the influence of pure dephasing ${\Gamma }_{12}^{\phi }$ on the power transmission coefficient $\left|t\right|{}^2$ for a resonantly incident weak probe with $\left|{\Omega }_{21}\right|/2\pi =1.78$ MHz. (b) The power transmission coefficient $\left|t\right|{}^2$ as a function of probe detuning, displaying partial absorption when no driving fields applied and strong-field-induced absorption, respectively. The inset shows single AA quantum switch for resonant probe signal, realized by fixing $\left|{\Omega }_{31}\right|$ and modulating $\left|{\Omega }_{32}\right|$.