We realize fast transport of ions in a segmented micro-structured Paul trap. The ion is shuttled over a distance of more than 10 4 times its groundstate wavefunction size during only 5 motional cycles of the trap (280 µm in 3.6 µs). Starting from a ground-state-cooled ion, we find an optimized transport such that the energy increase is as low as 0.10±0.01 motional quanta. In addition, we demonstrate that quantum information stored in a spin-motion entangled state is preserved throughout the transport. Shuttling operations are concatenated, as a proof-of-principle for the shuttling-based architecture to scalable ion trap quantum computing. . Scalable information processing in a multiplexed ion trap can be accomplished by having fixed processing sites where logic operations are performed, and ion qubits will be moved in and out of these regions by shuttling operations. The duration of such shuttling has to be much faster than the relevant decoherence times [4]. 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.Because quantum gate operations require ions close to the motional ground state and fast transport inherently creates motional excitation, the challenge is to develop transport protocols that guarantee sufficiency small energy transfer. In this work we demonstrate shuttling operations that are highly non-adiabatic while the final state of the ion is close to the motional groundstate. We also show that quantum information stored in both the motional and the spin degree of freedom is preserved through the shuttling.During a shuttling operation, the ion motion in the harmonic trapping potential is excited when the acceleration is sufficiently strong. This motional excitation is a harmonic oscillation, characterized by a well defined phase, thus allowing it to be canceled out by proper management of the forces involved during or after the transport. We experimentally demonstrate two methods of canceling the acquired motional excitation. One method uses two shuttles, where the transport to the destination generates the same net momentum transfer as the transport back, but is applied 180 • out of phase with respect to the secular oscillation of the ion (Fig. 1b). We refer to this as the pairwise energy-neutral transport. For the second scheme, the self-neutral transport we apply a sharp counter-"kick" to the ion at the end of a single transport operation, stopping its motion (Fig. 1c). This case of single-sided transport allows even faster shuttling and can be sequentially repeated since it is ener...
We experimentally demonstrate fast separation of a two-ion crystal in a microstructured segmented Paul trap. By the use of spectroscopic calibration routines for the electrostatic trap potentials, we achieve the required precise control of the ion trajectories near the \textit{critical point}, where the harmonic confinement by the external potential vanishes. The separation procedure can be controlled by three parameters: A static potential tilt, a voltage offset at the critical point, and the total duration of the process. We show how to optimize the control parameters by measurements of ion distances, trap frequencies and the final motional excitation. At a separation duration of $80 \mu$s, we achieve a minimum mean excitation of $\bar{n} = 4.16(0.16)$ vibrational quanta per ion, which is consistent with the adiabatic limit given by our particular trap. We show that for fast separation times, oscillatory motion is excited, while a predominantly thermal state is obtained for long times. The presented technique does not rely on specific trap geometry parameters and can therefore be adopted for different segmented traps
Abstract. We demonstrate the implementation of a spin qubit with a single 40 Ca + ion in a micro ion trap. The qubit is encoded in the Zeeman ground state levels m J = +1/2 and m J = −1/2 of the S 1/2 state of the ion. We show sideband cooling close to the vibrational ground state and demonstrate the initialization and readout of the qubit levels with 99.5% efficiency. We employ a Raman transition close to the S 1/2 -P 1/2 resonance for coherent manipulation of the qubit. We observe single qubit rotations with 96% fidelity and gate times below 5µs. Rabi oscillations on the blue motional sideband are used to extract the phonon number distribution. The dynamics of this distribution is analyzed to deduce the trap-induced heating rate of 0.3(1) phonons/ms.
We demonstrate a method to determine dipole matrix elements by comparing measurements of dispersive and absorptive light ion interactions. We measure the matrix element pertaining to the Ca II H line, i.e. the 4 2 S 1/2 ↔ 4 2 P 1/2 transition of 40 Ca + , for which we find the value 2.8928(43) ea0.Moreover, the method allows us to deduce the lifetime of the 4 2 P 1/2 state to be 6.904(26) ns, which is in agreement with predictions from recent theoretical calculations and resolves a longstanding discrepancy between calculated values and experimental results.PACS numbers: 37.10. Ty, 32.80.Qk, 03.67.Lx Methods for trapping and cooling single or few atoms, molecules or ions and manipulating them at the quantum level have opened up new avenues for precision laser spectroscopy. In particular, quantum logic techniques [1] have enabled a new accuracy regime of timekeeping with optical atomic clocks [2]. In contrast to atomic transition frequencies, dipole matrix elements and radiative lifetimes are still notoriously hard to determine at high accuracy, but are important for the quantification of black body radiation shifts of atomic clocks [3], interpretation of astrophysical spectra [4,5], novel approaches for the search for physics beyond standard model [6,7] and for testing the accuracy of atomic structure calculations [8].Regarding measurements of radiative lifetimes and transition matrix elements, established methods e.g. based on ion beams have been successfully complemented by novel techniques based on trapped particles. For 87 Rb, dipole matrix elements have been determined on the 10 −3 uncertainty level by diffraction in a condensate [9], while for the 6p 2 P o 1/2 state of 174 Yb + , the radiative lifetime has been measured by time-resolved counting of photons emitted from a single trapped ion [10]. A related technique was used for neutral 171 Yb in an optical lattice [11].The species Ca + is widely used in quantum optics experiments, and its II H line led to the discovery of the interstellar medium [12]. For 40 Ca + , branching ratios between different decay channels have been determined at uncertainties approaching the 10 −5 level [13,14], and lifetimes of metastable states have been accurately measured [15]. The radiative lifetime of the 4 2 P 1/2 excited state of 40 In this work, we determine the radiative decay rates and the lifetime of the 4 2 P 1/2 excited state of 40 Ca + together with the dipole matrix element of the 4 2 S 1/2 ↔ 4 2 P 1/2 transition. The cornerstone of our scheme is the comparison between the dispersive and absorptive interactions, which occur upon driving this transition with an off-resonant laser, see Fig. 1. As the method is based on the discrete discrimination of atomic states of a single trapped particle [17,18], it is robust against many systematic error sources which affect other existing methods.The off-resonant laser is characterized by its detuning ∆ from the 4 2 S 1/2 ↔ 4 2 P 1/2 transition, the Rabi frequency Ω and the relative amplitudes q , which characarXiv:1505.025...
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]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.