Sideband cooling of small ion Coulomb crystals in a Penning trap

Stutter, G.; Hrmo, Pavel; Jarlaud, Vincent; Joshi, Manoj K.; Goodwin, Joseph F.; Thompson, Richard C.

doi:10.1080/09500340.2017.1376719

Cited by 21 publications

(28 citation statements)

References 34 publications

(34 reference statements)

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“…The cooling sequence used in figure 13 is devised from the qualitative discussion above; other sequences are also possible, giving similar results. These studies are consistent with our experimental results reported in reference [24].…”

Section: Two-ion Chainsupporting

confidence: 94%

“…To understand the cooling dynamics of a two ion chain we show contour plots of sideband strengths as a function of Fock state number at ω z = 2π × 162 kHz (which gives ω B = √ 3ω z = 2π × 281 kHz). In this particular case where the L-D parameter is fairly large (η COM = 0.17 and η B = 0.13), we expect to have a large fraction of the population beyond the first minimum of the red sideband for both of the motional modes [24]. In order to bring all the population to the motional ground state, one has to target higher order sidebands repeatedly.…”

Section: Two-ion Chainmentioning

confidence: 97%

“…For qualitative comparison, experiments have been performed in our laboratory for the same trapping and laser conditions that are used in the simulations. The experimental apparatus and methodology have been discussed in reference [24]. After Doppler cooling, the ion is sideband cooled for a total of 20 ms and then a sideband spectrum is acquired.…”

Section: Sideband Cooling Outside the L-d Regimementioning

confidence: 99%

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Population dynamics in sideband cooling of trapped ions outside the Lamb-Dicke regime

et al. 2019

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We present the results of simulations of optical sideband cooling of atomic ions in a trap with a shallow potential well. In such traps, an ion cannot be Doppler cooled near to the Lamb-Dicke regime (η 2 (2 n + 1) 1). Outside the Lamb-Dicke regime, the sideband cooling dynamics are altered by the existence of various Fock states with weak coupling where the cooling becomes very slow. A 40 Ca + ion trapped in our Penning trap realizes such a situation, hence single stage cooling is inefficient to prepare the ion in the motional ground state. For these systems, it is necessary to study the cooling dynamics in detail and we show that it is possible to implement an optimized cooling sequence to achieve efficient ground state cooling. We also present the simulated cooling dynamics of two ions trapped in a Penning trap, where the presence of an additional motional mode requires a complicated cooling sequence in order to cool both axial modes to the ground state simultaneously. Additionally, we demonstrate the dissipative preparation of Fock states outside the Lamb-Dicke regime by sideband heating a single ion in a Penning trap.

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Section: Two-ion Chainsupporting

confidence: 94%

Section: Two-ion Chainmentioning

confidence: 97%

Section: Sideband Cooling Outside the L-d Regimementioning

confidence: 99%

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Population dynamics in sideband cooling of trapped ions outside the Lamb-Dicke regime

et al. 2019

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“…Sideband cooling from outside the Lamb-Dicke regime is still possible, but requires the addressing of higher order motional sidebands to prevent any accumulation of population in any of the coupling minima. This has been shown previously in RF traps [54,55] as well as in our Penning trap for the axial motion of single ions [8] and small Coulomb crystals [50]. In fact, cooling the axial modes of a two-ion chain at low trap frequency is similar to the problem of cooling the two radial modes of a single ion in that both require addressing higher order sidebands of both motions in turn.…”

Section: Sideband Coolingsupporting

confidence: 69%

Sideband cooling of the radial modes of motion of a single ion in a Penning trap

et al. 2019

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Doppler and sideband cooling are long standing techniques that have been used together to prepare trapped atomic ions in their ground state of motion. In this paper we study how these techniques can be extended to cool both radial modes of motion of a single ion in a Penning trap. We numerically explore the prerequisite experimental parameters for efficient Doppler cooling in the presence of an additional oscillating electric field to resonantly couple the radial modes. The simulations are supported by experimental data for a single 40 Ca + ion Doppler cooled to ∼100 phonons in both modes at a magnetron frequency of 52 kHz and a modified cyclotron frequency of 677 kHz. For these frequencies, we then show that mean phonon numbers of 0.35(5) for the modified cyclotron and 1.7(2) for the magnetron motions are achieved after 68 ms of sideband cooling.

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“…Straightforward modifications of this trap could include SmCo or radially-magnetized REPMs for improved field stability or higher uniform magnetic field, respectively. Future work will include introduction of axial laser cooling via installation of re-entrant viewports and trapping of the lower-mass ion species 9 Be + toward development of a compact frequency reference. The short-term magnetic field instability of this trap will also be characterized via electron spin resonance techniques and compared with that of traditional Penning traps [25].…”

mentioning

confidence: 99%

Doppler-cooled ions in a compact reconfigurable Penning trap

et al. 2020

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We report the design and experimental demonstration of a compact, reconfigurable Penning ion trap constructed with rare-earth permanent magnets placed outside of a trap vacuum enclosure. We describe the first observation of Doppler laser cooling of ions in a permanent magnet Penning trap. We detail a method for quantifying and optimizing the trap magnetic field uniformity in situ using a thermal beam of neutral 40 Ca precursor atoms. Doppler laser cooling of 40 Ca + is carried out at 0.65 T, and side-view images of trapped ion fluorescence show crystalline order for both two-and three-dimensional arrays. Measured 40 Ca + trap frequencies confirm the magnetic field characterization with neutral 40 Ca. The compact trap described here enables a variety of cold ion experiments with low size, weight, power, and cost requirements relative to traditional electromagnet-based Penning traps.Penning traps confine ions in three dimensions (3D) with a combination of a uniform magnetic field and quadrupolar electrostatic field. Unlike in radiofrequency (RF) Paul traps, ions in Penning traps exhibit no driven micromotion and, with the use of superconducting or permanent magnets, are confined with minimal power consumption. Traditional Penning traps consist of stacked hyperbolic or cylindrical electrode structures placed within the bore of a high-field ( > ∼ 1 T) electromagnet operating with normal or superconducting currents. Such traps have enabled record-setting precision measurements of charged-particle masses [1] and magnetic moments [2-4]. Doppler laser cooling of ions in Penning traps was first demonstrated in the late 1970s [5], and has facilitated frequency metrology with hyperfine transitions exhibiting > 550 s of coherent evolution [6] as well as precision measurements of hyperfine constants [7]. Recent work with laser-cooled ions in traditional Penning traps includes implementation of sub-Doppler laser cooling [8-10], sympathetic cooling of co-trapped molecular ions [11] and anti-matter [12], spin entanglement verified by spin squeezing [13], quantum simulation of Ising magnetism [14, 15], and optical force [16] (ion displacement [17]) detection with yN (pm) sensitivity.Miniaturization of Penning traps using permanent magnets is attractive for reduction of required laboratory infrastructure (e.g. volume, cryogens, power) and development of portable Penning traps. Replacement of large (> 1 m 3 ) electromagnets with smaller (∼ 10 −4 m 3 ) rare earth permanent magnets (REPMs) confers, for example, improved optical access for ion interrogation and imaging, shorter overall laser beam paths, and reduced fringing magnetic fields. Over the past three decades, a number of compact Penning traps based on REPMs have been demonstrated for applications including portable mass spectrometry [18], ion storage [19][20][21], and spectroscopy of highly-charged ions [22]. Rare earth magnets of the SmCo and NdFeB varieties have remanences and coercivities > 1 T, allowing for Penning confinement of ions with masses up to ∼ 100 amu with a t...

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Sideband cooling of small ion Coulomb crystals in a Penning trap

Cited by 21 publications

References 34 publications

Population dynamics in sideband cooling of trapped ions outside the Lamb-Dicke regime

Population dynamics in sideband cooling of trapped ions outside the Lamb-Dicke regime

Sideband cooling of the radial modes of motion of a single ion in a Penning trap

Doppler-cooled ions in a compact reconfigurable Penning trap

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