Near-ground-state transport of trapped-ion qubits through a multidimensional array

Abstract

We have demonstrated transport of 9 Be + ions through a two-dimensional Paul-trap array that incorporates an X junction, while maintaining the ions near the motional ground state of the confining potential well. We expand on the first report of the experiment in Blakestad et al. [Phys. Rev. Lett. 102, 153002 (2009)], including a detailed discussion of how the transport potentials were calculated. Two main mechanisms that caused motional excitation during transport are explained, along with the methods used to mitigate such excitation. We reduced the motional excitation below the results in the above reference by a factor of approximately 50. The effect of a mu-metal shield on qubit coherence is also reported. Finally, we examined a method for exchanging energy between multiple motional modes on the few-quanta level, which could be useful for cooling motional modes without directly accessing the modes with lasers. These results establish how trapped ions can be transported in a large-scale quantum processor with high fidelity.

Controlling Fast Transport of Cold Trapped Ions

“…Furthermore, it is desirable to reduce the total time consumption of all relevant operations, where shuttling will contribute a considerable amount [5], and aim for the performance of the naturally fast solid state architectures [6]. So far, ion shuttling in a multiplexed trap has been demonstrated together with additional sympathetic cooling [7], and in the adiabatic regime, where the transient displacement of the ion is smaller than the size of the its wavepacket [8,9]. Transport of neutral atoms have also been performed using magnetic [10] or optical [11] techniques.…”

High-Fidelity Universal Gate Set forBe9+Ion Qubits

“…However, a disadvantage of 9 Be + ion qubits compared to some heavier ions such as 40 Ca + and 43 Ca + [12,13] has been the difficulty of producing and controlling the ultraviolet (313 nm) light required to drive 9 Be + stimulated-Raman transitions. In the work reported here, we use an ion trap array designed for scalable QIP [14] and take advantage of recent technological developments with lasers and optical fibers that improve beam quality and pointing stability. We also implement active control of laser pulse intensities to re- showing the load zone L and experiment zone E. Ions are transported from L to E with time-varying potentials applied to the segmented control electrodes (colored orange hues).…”

“…By characterizing the effects of known error sources with numerical simulations and calibration measurements, we deduce an entangling gate infidelity or error of = 8(4) × 10 −4 , where = 1 -F, and F is the fidelity. Along with Ref.[13]; these appear to be the highest two-qubit gate fidelities reported to date.The ions are confined in a multi-segmented linear Paul trap (Fig.1) designed to demonstrate scalable QIP [14][15][16]. Radio frequency (RF) potentials, with frequency ω RF 2π × 83 MHz and amplitude V RF 200 V, are applied to the RF electrodes to provide confinement transverse to the main trap channels.…”

“…The ions are confined in a multi-segmented linear Paul trap (Fig.1) designed to demonstrate scalable QIP [14][15][16]. Radio frequency (RF) potentials, with frequency ω RF 2π × 83 MHz and amplitude V RF 200 V, are applied to the RF electrodes to provide confinement transverse to the main trap channels.…”

Comparison of ancilla preparation and measurement procedures for the Steane [[7,1,3]] code on a model ion-trap quantum computer

“…A scalable architecture has been proposed based on shuttling ions between traps [11] and work is ongoing to implement this architecture experimentally [12][13][14][15][16][17][18][19][20]. This framework has been the basis for a number of studies on the resource requirements for implementing large quantum algorithms [21][22][23] and has also been considered as the elementary logical unit of hybrid schemes using photonic interconnects [24].…”