Abstract

Trapped atomic ions are among the most promising candidates for stationary qubits within a quantum network. In such a network, information can be distributed between ions by the exchange of photons. This requires a highly efficient light-matter interface, which can be implemented by coupling the ion to a high finesse optical cavity in order to make use of the concepts of cavity QED. Since the ion-cavity coupling scales inversely with the square root of the mode volume, we have developed a light-matter interface consisting of a single 174Yb⁺ ion coupled to a miniaturized optical fiber-cavity of only 170µm length [1]. Single photons at 935nm are emitted into the cavity mode. Despite the photon being intrinsically coupled into a single mode fiber, the correlation between the polarization of the photon and the spin state of the ion is preserved [2]. When a faint laser beam is coupled into the cavity the absorption of photons is also enhanced. This allows coupling to other key quantum systems, where the efficiency can drop due to a significant bandwidth mismatch. To demonstrate this, we measure the absorption of photons from a semiconductor quantum dot (QD), which is tuned to the ion’s resonance frequency [3]. We investigate how the absorption probability is altered depending on the QDs spectral emission properties, which depend on the QD driving regime. This builds the foundation for a hybrid quantum network consisting of two fundamentally different quantum systems potentially serving as quantum processor (QD) and quantum memory (ion), respectively.

© 2015 Optical Society of America