Electromagnetically Induced Transparency on a Single Artificial Atom

We present experimental observation of electromagnetically induced transparency (EIT) on a single macroscopic artificial “atom” (superconducting quantum system) coupled to open 1D space of a transmission line. Unlike in an optical media with many atoms, the single-atom EIT in 1D space is revealed in suppression of reflection of electromagnetic waves, rather than absorption. The observed almost 100% modulation of the reflection and transmission of propagating microwaves demonstrates full controllability of individual artificial atoms and a possibility to manipulate the atomic states. The system can be used as a switchable mirror of microwaves and opens a good perspective for its applications in photonic quantum information processing and other fields.

Figure 1

Three-level cascade system. (a) Schematic of the three-level cascade atom used to produce electromagnetically induced transparency—the physical phenomena for the quantum switch. Transmission of a weak propagating wave at the frequency ${\omega }_p$ close to the transition frequency ${\omega }_{21}$ is controlled by another field coupling states $|2⟩$ and $|3⟩$. The corresponding Rabi drive amplitudes are denoted by ${\Omega }_c$ and ${\Omega }_p$, respectively. (b) Transmission spectrum for $|1⟩\leftrightarrow |2⟩$ transition. (c) Spectrum of $|2⟩\leftrightarrow |3⟩$ transition. The spectroscopy signal appears only around the degeneracy point. The transition frequency between states $|2⟩$ and $|3⟩$ at the degeneracy ($\delta \Phi =0$) is ${\omega }_{32}=24.465\mathrm{GHz}$. (d) Spectrum of $|1⟩\leftrightarrow |3⟩$ transition. At the degeneracy point $\delta \Phi =0$ the transition is prohibited, and the spectroscopy signal vanishes indicating that the cascade system is realized.

Figure 2

Transmission coefficient near the probe wave resonance ($\delta {\omega }_p=0$). (a) and (b) are real and imaginary parts of the probe signal transmission coefficient at the different control field amplitudes ${\Omega }_c$, specified in (b). The curves show typical dispersion for EIT. (c) and (d) present calculations of real and imaginary parts for the probe signal transmission coefficient for the same set of ${\Omega }_c$ as in (a) and (b).

Figure 3

Quantum switch operation. (a) Power transmission coefficient $T$ vs control field amplitude ${\Omega }_c$ and probe frequency. The single resonant dip in the transmission is split into two under the large control field amplitudes. (b) $T$ for resonant probe signal vs control field amplitude. The experimentally measured $T$ is presented by red circles, and the black line is calculated $|t{|}^2$ from Eq. (5). The achieved contrast in the transmitted power is 96%.