Ion Photon Entanglement in a Parabolic Mirror Trap
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Single trapped ion qubits are excellent candidates for quantum computation and information, and they also possess the ability to coherently couple to single photons. Efficient fluorescence collection is the most challenging part in remotely entangled ion qubit state generation. To address this issue, I developed an ion trap combining a reflective parabolic surface with trap electrodes. This parabolic trap design covers a solid angle of 2π steradians, and allows precise ion placement at the focus of parabola. I measured 39% fluorescence collection efficiency from a single ion with this mirror trap, and 10% single-mode optical fiber coupling efficiency out of the total reflected fluorescence. A deformable mirror was used to reduce aberration to less than 2.8 times over the diffraction limit. By analyzing the ion behavior in this RF quadrupole trap, I determined that the optical resolution is limited by ion micro-motion. When trapping singly ionized barium, entanglement can be established between its energy level and the polarization of fluorescence. This setup generates an entangled ion-photon pair at 1 Hz with a mode-locked pulsed laser as the excitation source. Quantum correlation was measured between the ion spin state and the photon polarization state, and found to be above the 50% classical limit and the 71% threshold required for a Bell’s inequality violation test.
- Physics