Stimulated Raman adiabatic passage for improved performance of a cold-atom electron and ion source

Sparkes, B. M.; Murphy, D.; Taylor, Robert J.; Speirs, Rory W.; McCulloch, A. J.; Scholten, R. E.

doi:10.1103/physreva.94.023404

Cited by 13 publications

(15 citation statements)

References 51 publications

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“…If such a super-resolution ionization scheme were realized, it would result in an electron beam with a relative energy spread better than 1 part in 10 5 , removing the need for a monochromator for many experiments. By implementing a high-efficiency photoexcitation scheme, for example, one similar to that already implemented in a cold atom source [44], this would allow for the creation of a highcurrent highly monochromatic electron beam. Additionally, the application of the same system to focused ion-beam science would be extremely powerful.…”

Section: Discussionmentioning

confidence: 99%

Field ionization of Rydberg atoms for high-brightness electron and ion beams

et al. 2017

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We present an ionization mechanism for use in a cold atom electron source with the goal of producing highly monochromatic electron beams. We experimentally produce a map of the Stark states of 85 Rb below the ionization threshold and identify states that undergo selective field ionization. The properties of an electron beam produced by field-assisted ionization of such states are quantified. A theoretical framework is established to predict the improvement to beam quality when ionization is conducted above the ionization threshold, where ionization conditions are typically more favorable than below the threshold. Calculations suggest that selective ionization of Rydberg states may offer a pathway to the production of high-brightness, highly monochromatic ion and electron beams.

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Section: Discussionmentioning

confidence: 99%

Field ionization of Rydberg atoms for high-brightness electron and ion beams

et al. 2017

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“…As φ is varied the final population in |0 oscillates. Error bars indicate projection noise (68% CI).nificant improvement on the highest STIRAP efficiency observed with neutral Rydberg atoms (60%) [20][21][22].We use the double STIRAP sequence to introduce a geometric phase following the protocol recently demonstrated with a solid-state qubit [23]. During the double STIRAP sequence, the dark state moves on the surface of the Bloch sphere spanned by |0 and |r from the |0 pole to the |r pole then back to |0 (Fig.…”

mentioning

confidence: 99%

“…nificant improvement on the highest STIRAP efficiency observed with neutral Rydberg atoms (60%) [20][21][22].…”

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confidence: 99%

Coherent Control of a Single Trapped Rydberg Ion

et al. 2017

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Trapped Rydberg ions are a promising novel approach to quantum computing and simulations [1][2][3]. They are envisaged to combine the exquisite control of trapped ion qubits [4] with the fast two-qubit Rydberg gates already demonstrated in neutral atom experiments [5][6][7]. Coherent Rydberg excitation is a key requirement for these gates. Here, we carry out the first coherent Rydberg excitation of an ion and perform a single-qubit Rydberg gate, thus demonstrating basic elements of a trapped Rydberg ion quantum computer.Systems of trapped ion qubits have set numerous benchmarks for single-qubit preparation, manipulation, and readout [8]. They can perform low error entanglement operations [9,10] with up to 14 ion qubits [11]. Still, a major limitation towards realizing a large-scale trapped ion quantum computer or simulator is the scalability of entangling quantum logic gates [12].Arrays of neutral atoms in dipole traps offer another promising approach to quantum computation and simulation. Here, qubits are stored in electronically low-lying states and multi-qubit gates may be realized by exciting atoms to Rydberg states [6,7,13,14]. Rydberg states are exotic states of matter in which the valence electron is excited to high principal quantum numbers. They can have extremely high dipole moments and may interact strongly with each other, which has allowed entanglement generation [15,16] and fast two-qubit Rydberg gates [5] in neutral atom systems.A system of trapped Rydberg ions may combine the advantages of both technologies. Electronically lowlying states may be used as qubit states and fast multiqubit gates are envisaged by coherently exciting ions to Rydberg states and employing dipolar interactions between them [1,17]. Multi-qubit gates commonly used in trapped ion systems suffer scalability restrictions due to spectral crowding of motional modes [12]. This issue does not affect multi-qubit Rydberg gates thus a trapped Rydberg ion quantum computer offers an alternate approach to a scalable system. An unanswered question was whether trapped ions can be excited to Rydberg states in a coherent fashion as is required for multi-qubit Rydberg gates. In our experiment we study a single 88 Sr + ion confined in a linear Paul trap. Three atomic levels in a ladder configuration are coupled using two UV lasers (Fig. 1). The qubit state |0 is coupled to the excited state |e by the pump laser at 243 nm with Rabi frequency Ω P . |e is coupled in turn to the Rydberg state |r (42S 1/2 , m J = −1/2) using the Stokes laser at 307 nm with Rabi frequency Ω S . The experimental setup is described in detail in the Methods section and in [3].We can use the two-photon coupling for coherent control of the Rydberg excitation. At two-photon resonance (|0 to |r ) the coupling Hamiltonian has a "dark" eigenstate |Φ dark ∼ Ω S e iφ |0 − Ω P |r (Methods), which is named so because it does not contain any component of |0-|rRydberg excitation by STIRAP shown by comparing application of the single and the double STIRAP pulse sequences. The sin...

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“…To perform these measurements in a single shot with the same parameters and signal-to-noise ratio would require 1000 times more electrons per shot, approximately 10 8 , which can be achieved with existing photocathode sources [16,40]. The CAES has demonstrated bunches of 10 6 electrons [22], and a number of strategies should enable much larger bunches, such as increasing the density of the MOT, selecting more efficient ionization pathways [41], or the use of a higher intensity blue ionization laser.…”

Section: Resultsmentioning

confidence: 99%

Time-resolved brightness measurements by streaking

Torrance

Speirs

McCulloch

et al. 2018

Phys. Rev. Accel. Beams

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Brightness is a key figure of merit for charged particle beams, and time-resolved brightness measurements can elucidate the processes involved in beam creation and manipulation. Here we report on a simple, robust, and widely applicable method for the measurement of beam brightness with temporal resolution by streaking one-dimensional pepperpots, and demonstrate the technique to characterize electron bunches produced from a cold-atom electron source. We demonstrate brightness measurements with 145 ps temporal resolution and a minimum resolvable emittance of 40 nm rad. This technique provides an efficient method of exploring source parameters and will prove useful for examining the efficacy of techniques to counter space-charge expansion, a critical hurdle to achieving single-shot imaging of atomic scale targets.

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Stimulated Raman adiabatic passage for improved performance of a cold-atom electron and ion source

Cited by 13 publications

References 51 publications

Field ionization of Rydberg atoms for high-brightness electron and ion beams

Field ionization of Rydberg atoms for high-brightness electron and ion beams

Coherent Control of a Single Trapped Rydberg Ion

Time-resolved brightness measurements by streaking

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