Ion Trapping

Trapped ions are one of the leading candidates for the implementation of local processors due to their long-lived qubit states and ability to perform quantum operations with high fidelity. A promising scheme for communication between distant nodes combines local quantum operations with heralded remote entanglement using photonic links between nodes [1]. Photons are an obvious choice for carrying quantum information between distant nodes due to their ease of propagation though free-space or optical fibers.

We trap single ions using a segmented four-blade Paul trap (Fig. 1). This trap is designed to allow for a large solid angle of collection (0.6 NA) of emitted photons without obstruction from trap electrodes. The ability to collect photons over a large solid angle increases the probability to detect entanglement between the emitted photon and the trapped barium ion (Fig. 2) [2].


[1] Monroe, C. and Raussendorf, R. and Ruthven, A. and Brown, K. R. and Maunz, P. and Duan, L.-M. and Kim, J. Phys. Rev. A 89, (2014).

[2] J. D. Siverns, X. Li, and Q. Quraishi Applied Optics Vol. 56, Issue 3, (2017).

Fig 1: Our four blade Paul trap, mounted inside a ultra-high vacuum chamber, with inset of CCD image of trapped ions.

Fig 2: Probability of entanglement between the trapped barium ion and an emitted photon for three different entanglement schemes as a function of the numerical aperture (NA) of the photon collection lens as described in [2].