Sympathetic ground-state cooling and coherent manipulation with two-ion crystals

Rohde, H.; Gulde, S.; Roos, C. F.; Barton, P. A.; Leibfried, D.; Eschner, J.; Schmidt‐Kaler, F.; Blatt, R.

doi:10.1088/1464-4266/3/1/357

Cited by 93 publications

(91 citation statements)

References 21 publications

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“…Rescattered light will then be absent only if the atom is in the shelved state and hence the the molecule in the desired internal state |χ d mol . several experiments show that it is feasible to achieve W 0 = 95% population in |0 Tr in the case of two atomic ion species [21,22]. The same degree of cooling is expected for an atomic-molecular ion system.…”

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confidence: 82%

Probabilistic state preparation of a single molecular ion by projection measurement

Vogelius¹,

Madsen²,

Drewsen³

2006

J. Phys. B: At. Mol. Opt. Phys.

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We show how to prepare a single molecular ion in a specific internal quantum state in a situation where the molecule is trapped and sympathetically cooled by an atomic ion and where its internal degrees of freedom are initially in thermal equilibrium with the surroundings. The scheme is based on conditional creation of correlation between the internal state of the molecule and the translational state of the collective motion of the two ions, followed by a projection measurement of this collective mode by atomic ion shelving techniques. State preparation in a large number of internal states is possible.PACS numbers: 33.80. Ps,33.20.Vq,82.37.Vb Investigations of production and trapping of cold neutral and ionic molecules [1,2,3] point to a wealth of possible applications, including studies of molecular BoseEinstein condensates [4,5,6,7,8], investigations of collision and reaction dynamics at low temperature [9], high-resolution spectroscopy [10], coherent control experiments [11], and state specific reactions studies [12,13]. For much of this research, long-term localized and statespecific targets are highly desirable. One way to obtain such targets is to work with trapped molecular ions sympathetically cooled by atomic ions where previous investigations show that molecular ions can be translationally cooled to temperatures of a few mK, at which stage they become immobile and localize spatially in Coulomb crystal structures [14,15]. Though these molecules are translationally cold, studies indicate that the internal degrees of freedom of at least smaller hetero-nuclear molecules, due to their interaction with the black-body radiation (BBR), are close to be in equilibrium with the temperature of the surroundings [16]. This is not unexpected since the many order of magnitude difference between the internal transitions frequencies in the molecule ( 10 11 Hz) and the frequency of the collective vibrational modes in the Coulomb crystals ( 10 7 Hz) leads to very inefficient coupling between these degrees of freedom. Several schemes were recently proposed to cool the rotational temperature of translationally cold heteronuclear molecular ions [17,18].Here, we focus on an alternative route to the production of molecular ions in specific states. The physical system used for this purpose consists of one trapped molecular ion sympathetically cooled by a simultaneously trapped atomic ion. Such a situation was previously realized and it was shown to be possible to determine the molecular ion species non-destructively by a classical resonant excitation of one of the two axial collective modes of the two-ion system [15]. With this setup, we now propose to exploit the quantum aspect of the same collective modes to create correlations between the internal state of the molecular ion and the collective motional state in the trap potential. Previously, correlations in two-ion systems were essential in, e.g., demonstrations of quantum logical gates [19] and in a proposal for high-resolution spectroscopy [20].As depicted in Fig. 1, th...

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mentioning

confidence: 82%

Probabilistic state preparation of a single molecular ion by projection measurement

Vogelius¹,

Madsen²,

Drewsen³

2006

J. Phys. B: At. Mol. Opt. Phys.

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“…Linear blade traps, with heating rates as low as a few quanta per second and trap depths on the order of tens of eV, are known to have long ion lifetimes. 54,55 When considering the implementation of dielectric mirrors into an ion trap, one should keep in mind the effects of dielectrics on the ion. Charges on dielectrics in vacuum are quasi-permanent and distort the ion-trap potential.…”

Section: A Experimental Design Considerationsmentioning

confidence: 99%

Integrated fiber-mirror ion trap for strong ion-cavity coupling

Brandstätter

McClung

Schüppert

et al. 2013

Review of Scientific Instruments

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We present and characterize fiber mirrors and a miniaturized ion-trap design developed to integrate a fiber-based Fabry-Perot cavity (FFPC) with a linear Paul trap for use in cavity-QED experiments with trapped ions. Our fiber-mirror fabrication process not only enables the construction of FFPCs with small mode volumes, but also allows us to minimize the influence of the dielectric fiber mirrors on the trapped-ion pseudopotential. We discuss the effect of clipping losses for long FFPCs and the effect of angular and lateral displacements on the coupling efficiencies between cavity and fiber. Optical profilometry allows us to determine the radii of curvature and ellipticities of the fiber mirrors. From finesse measurements, we infer a single-atom cooperativity of up to 12 for FFPCs longer than 200 μm in length; comparison to cavities constructed with reference substrate mirrors produced in the same coating run indicates that our FFPCs have similar scattering losses. We characterize the birefringence of our fiber mirrors, finding that careful fiber-mirror selection enables us to construct FFPCs with degenerate polarization modes. As FFPCs are novel devices, we describe procedures developed for handling, aligning, and cleaning them. We discuss experiments to anneal fiber mirrors and explore the influence of the atmosphere under which annealing occurs on coating losses, finding that annealing under vacuum increases the losses for our reference substrate mirrors. X-ray photoelectron spectroscopy measurements indicate that these losses may be attributable to oxygen depletion in the mirror coating. Special design considerations enable us to introduce a FFPC into a trapped ion setup. Our unique linear Paul trap design provides clearance for such a cavity and is miniaturized to shield trapped ions from the dielectric fiber mirrors. We numerically calculate the trap potential in the absence of fibers. In the experiment additional electrodes can be used to compensate distortions of the potential due to the fibers. Home-built fiber feedthroughs connect the FFPC to external optics, and an integrated nanopositioning system affords the possibility of retracting or realigning the cavity without breaking vacuum.

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“…Laser cooling, for example, is clearly not applicable here as the process of light scattering causes decoherence. The same problem arises in scalable ion trap quantum computing, and there it has been overcome using sympathetic cooling schemes, in which ions used to encode qubits are cooled via a coulomb interaction with either a single ion which is directly laser-cooled [17] or another species of ions which are directly laser-cooled [18]. In a different context, sympathetic cooling schemes are also used widely in the field of cold quantum gases, where they have been used to cool different spin states of the same atomic species [19], to cool different Bosonic species [20], and to cool Fermi gases brought into contact with a BEC [21].…”

Section: Introductionmentioning

confidence: 99%

Single-atom cooling by superfluid immersion: A nondestructive method for qubits

2004

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We present a scheme to cool the motional state of neutral atoms confined in sites of an optical lattice by immersing the system in a superfluid. The motion of the atoms is damped by the generation of excitations in the superfluid, and under appropriate conditions the internal state of the atom remains unchanged. This scheme can thus be used to cool atoms used to encode a series of entangled qubits non-destructively. Within realisable parameter ranges, the rate of cooling to the ground state is found to be sufficiently large to be useful in experiments.

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Sympathetic ground-state cooling and coherent manipulation with two-ion crystals

Cited by 93 publications

References 21 publications

Probabilistic state preparation of a single molecular ion by projection measurement

Probabilistic state preparation of a single molecular ion by projection measurement

Integrated fiber-mirror ion trap for strong ion-cavity coupling

Single-atom cooling by superfluid immersion: A nondestructive method for qubits

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