Coherent Diabatic Ion Transport and Separation in a Multizone Trap Array

We investigate the dynamics of single and multiple ions during transport between and separation into spatially distinct locations in a multizone linear Paul trap. A single ${}^9\mathrm{Be}^{+}$ ion in a $\sim 2\mathrm{MHz}$ harmonic well was transported $370\mu \mathrm{m}$ in $8\mu \mathrm{s}$, corresponding to 16 periods of oscillation, with a gain of 0.1 motional quanta. Similar results were achieved for the transport of two ions. We also separated chains of up to 9 ions from one potential well to two distinct potential wells. With two ions this was accomplished in $55\mu \mathrm{s}$, with excitations of approximately two quanta for each ion. Fast transport and separation can significantly reduce the time overhead in certain architectures for scalable quantum information processing with trapped ions.

Figure 1

Schematic of the linear Paul (quadrupole) ion trap electrode structure showing the two diagonally opposite segmented dc electrodes (not to scale; trap details in 5, 6, 7, 21). Ions are loaded in a region to the left of zone $O1$ and initially transported to zone $A$. Trap radio-frequency (rf) electrodes (not shown) are referenced to a common ground potential.

Figure 2

Rabi flopping trace on the MAS and MSS after transport from zone $A$ to $B$ [12]. Here we fit to thermal distributions that give $\overline{n}=0.19\pm 0.02$ from the MAS fit and $\overline{n}=0.17\pm 0.01$ from the MSS fit. The axial frequency was $\omega /(2\pi )=1.972(1)\mathrm{MHz}$ with a Lamb-Dicke parameter $\eta =0.479$.

Figure 3

Rabi flopping trace on the MAS following transport in $8\mu \mathrm{s}$ in which $\alpha (t_T)\ne 0$. The figure shows a coherent state fit with $\overline{n}=6.4\pm 0.2$, corresponding to $|\alpha |=2.53\pm 0.04$. The axial frequency was $\omega /(2\pi )=1.919(2)\mathrm{MHz}$ and the Lamb-Dicke parameter was $\eta =0.486$.

Figure 4

Ion fluorescence counts in zone $A$ as a function of the offset potential $V_{O2}$ during separation relative to a central value. Each step increase of the counts corresponds to the presence of an additional ion in zone $A$ after separation. A single ion produced approximately 10 average photomultiplier tube (PMT) counts in $200\mu \mathrm{s}$, but as more ions were added in zone $A$, the crystal was no longer uniformly illuminated by the detection beam and the signal dropped below 10 counts per ion.