A quantum repeater node with trapped ions: a realistic case example

Abstract

We evaluate the feasibility of the implementation of two quantum repeater protocols with an existing experimental platform based on a 40 Ca + -ion in a segmented micro trap, and a third one that requires small changes to the platform. A fiber cavity serves as an ion-light interface. Its small mode volume allows for a large coupling strength of g c = 2π × 20 MHz despite comparatively large losses κ = 2π × 18.3 MHz. With a fiber diameter of 125 μm, the cavity is integrated into the microstructured ion trap, which in turn is used to transport single ions in and out of the interaction zone in the fiber cavity. We evaluate the entanglement generation rate for a given fidelity using parameters from the experimental setup. The DLCZ protocol [1] and the hybrid protocol [2] outperform the EPR protocol [3]. We calculate rates of more than than 100 s −1 for non-local Bell state fidelities larger than 0.95 with the existing platform. We identify parameters which mainly limit the attainable rates, and conclude that entanglement generation rates of 750 s −1 at fidelities of 0.95 are within reach with current technology. arXiv:1508.05272v2 [quant-ph]

Cryogenic platform for coupling color centers in diamond membranes to a fiber-based microcavity

“…While photonic crystal cavities are attractive due to strong mode confinement [15] and their intrinsic robustness, processing the crystal environment can lead to spectral diffusion and the optical outcoupling of the signal is challenging [23]. Open, fiber-based Fabry-Pérot microcavities have been successfully utilized for various physical systems, like neutral atoms [24,25], ions [26][27][28] or quantum dots [29], as they allow for direct coupling between the fiber and the cavity mode, small mode volumes as well as full spectral and spatial tunability. In recent experiments, color centers incorporated in nanodiamonds were coupled to fiber-based microcavities [18,20,30].…”

Achievements and perspectives of optical fiber Fabry–Perot cavities

“…In Fig. 8 we compare atom-cavity systems prepared by experimenters for the strong coupling regime over the past decades with respect to their g∕ and ∕ -values for both bulk cavity experiments [51][52][53] and FFPCs [42][43][44][45][46][47][48][49][50]. Selected sets of parameters for the ( g, , )-values used in different laboratories show a clear tendency to take advantage of FFPC properties especially in the fast cavity regime, i.e.…”

“…At the present time investigations are underway with respect to numerous technical improvements especially with regard to ion coupled FFPCs: Unwanted stray fields are to be controlled by means of integrated electrodes (see Sect. 2.8); a natural extension of FFPCs is integration with miniaturized ion traps [42,44,48]; improved mirror fabrication for long cavities can mitigate problems with charging of dielectric surfaces [31].…”

Achievements and Perspectives of Optical Fiber Fabry-Perot Cavities

“…8. A non-exhaustive survey of normalized parameter sets {g, κ, γ} and C = g 2 /2κγ used in cavity QED experiments with fiber based Fabry-Perot resonators (FFPCs sorted from left to right: [37][38][39][40][41][42][43][44][45]) with respect to performance in atom field coupling strength g/γ vs. resonator field fiber coupling rate κ/γ. For comparison a small set of bulk cavity system parameters is shown, too, from [46][47][48] sorted from top to bottom.…”