Increasing the Brightness of Cold Ion Beams by Suppressing Disorder-Induced Heating with Rydberg Blockade

Murphy, D.; Scholten, R. E.; Sparkes, B. M.

doi:10.1103/physrevlett.115.214802

Cited by 18 publications

(12 citation statements)

References 45 publications

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“…Coulomb anti-blockade may also be useful to Rydberg-based focused ion beam experiments e.g. [58], enabling higher Rydberg excitation/ion production rates than are allowed due to Rydberg blockade, whilst suppressing disorder-induced heating.…”

Section: Resultsmentioning

confidence: 99%

Coulomb anti-blockade in a Rydberg gas

et al. 2019

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We perform a comprehensive investigation of the coupling between a Rydberg-dressed atomic gas and an ultra-cold plasma (UCP). Using simultaneous time-resolved measurements of both neutral atoms and ions, we show that plasma formation occurs via a Coulomb anti-blockade mechanism, in which background ions DC Stark shift nearby atoms into resonance at specific distances. The result is a highly correlated growth of the Rydberg population that shares some similarities with that previously observed for van der Waals interactions. We show that a rate equation model that couples the laserdriven Rydberg gas to the UCP via a Coulomb anti-blockade mechanism accurately reproduces both the plasma formation and its subsequent decay. Using long-lived high angular momentum states as a probe, we also find evidence of a crossover from Coulomb anti-blockade to Coulomb blockade at high density. As well as shedding light on loss mechanisms in Rydberg-dressed gases, our results open new ways to create low-entropy states in UCPs. Introduction/motivationHybrid quantum systems of ultracold atoms and ions are emerging as a platform for fundamental research in quantum physics [1]. Recently, Rydberg states have received attention as a way to control the coupling between ionic and atomic systems [2-5], for example, using Coulomb blockade from a single ion to suppress Rydberg excitation [6]. Ultracold mixtures of Rydberg atoms and ions have also been studied in the context of cold Rydberg gases, where it was generally found that ions are almost always present due to processes such as collisions between nearby Rydberg atoms and blackbody photoionization. Indeed, studies using resonant laser excitation of Rydberg states have shown an ultra-cold plasma (UCP) under conditions of strong excitation, both in the pulsed [7-9] and continuously driven [10, 11] regimes.In this paper, we demonstrate that an off-resonant excitation of the Rydberg state can be used to tailor the the interaction between Rydberg atoms and ions in an ultracold gas. We show that plasma formation occurs via a Coulomb anti-blockade mechanism, illustrated in figure 1(b), where background ions DC Stark shift nearby atoms into resonance at specific distances. The result is a highly correlated 'facilitated growth' of the Rydberg population that shares some similarities with that previously observed using van der Waals anti-blockade [12]. A rate equation model that couples the driven Rydberg gas to an UCP via this correlated excitation model accurately reproduces both the initial creation and subsequent decay of the observed ion signal. At longer times, the ionization of long-lived high angular momentum Rydberg states produced in the plasma provides evidence for the interplay between Coulomb blockade [6] and Coulomb anti-blockade in the plasma. In future experiments, controlling this process could provide a route to creating an UCP with a strongly correlated ionic state [13].Our results also provide a strategy for minimising losses due to ionization in cold Rydberg gas experiments, p...

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Section: Resultsmentioning

confidence: 99%

Coulomb anti-blockade in a Rydberg gas

et al. 2019

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“…For example, it has recently been shown that Rydberg interactions have the possibility of suppressing stochastic Coulomb effects, enhancing the ion beam’s brightness. 174 These same effects can also result in a quasi-deterministic ion beam from a purely stochastic cloud of atoms. 175 A single “ion on demand” can also be generated using feedback control of loading in a MOT.…”

Section: Discussionmentioning

confidence: 96%

Bright focused ion beam sources based on laser-cooled atoms

McClelland

Steele

Knuffman

et al. 2016

Applied Physics Reviews

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Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future.

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“…The large dipole moments of Rydberg atoms enables Rydberg blockade, where excitation of one atom inhibits the excitation of other atoms close by [23,24]. Rydberg blockade can, in principle, reduce disorder-induced heating [30,31], and thereby reduce emittance and increase focusabiltiy in a CAEIS [32]. By enforcing a separation between Rydberg atoms larger than the laser excitation volume, blockade can allow selective excitation of discrete separated atoms, and thereby create a deterministic single ion source [33][34][35].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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We implement high-efficiency coherent excitation to a Rydberg state using stimulated Raman adiabatic passage in a cold atom electron and ion source. We achieve an efficiency of 60% averaged over the laser excitation volume with a peak efficiency of 82%, a 1.6 times improvement relative to incoherent pulsed-laser excitation. Using pulsed electric field ionization of the Rydberg atoms we create electron bunches with durations of 250 ps. High-efficiency excitation will increase source brightness, crucial for ultrafast electron diffraction experiments, and coherent excitation to highlying Rydberg states could allow for the reduction of internal bunch heating and the creation of a high-speed single ion source.

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Increasing the Brightness of Cold Ion Beams by Suppressing Disorder-Induced Heating with Rydberg Blockade

Cited by 18 publications

References 45 publications

Coulomb anti-blockade in a Rydberg gas

Coulomb anti-blockade in a Rydberg gas

Bright focused ion beam sources based on laser-cooled atoms

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

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