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Search Results: 1 - 10 of 401242 matches for " M. Drewsen "
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Ground state sideband cooling of an ion in a room temperature trap with a sub-Hertz heating rate
G. Poulsen,Y. Miroshnychenko,M. Drewsen
Physics , 2012,
Abstract: We demonstrate resolved sideband laser cooling of a single 40Ca+ ion in a macroscopic linear radio frequency trap with a radial diagonal electrode spacing of 7 mm and an rf drive frequency of just 3.7 MHz. For an oscillation frequency of 585 kHz along the rf-field-free axis, a ground state population of 99+-1% has been achieved, corresponding to a temperature of only 6 microkelvin. For several oscillation frequencies in the range 285 - 585 kHz, heating rates below one motional quantum per second have been measured at room temperature. The lowest measured heating power is about an order of magnitude lower than reported previously in room temperature, as well as cryogenically cooled traps.
Microwave quantum logic spectroscopy and control of molecular ions
M. Shi,P. F. Herskind,M. Drewsen,I. L. Chuang
Physics , 2013, DOI: 10.1088/1367-2630/15/11/113019
Abstract: A general method for rotational microwave spectroscopy and control of polar molecular ions via direct microwave addressing is considered. Our method makes use of spatially varying AC Stark shifts, induced by far off-resonant, focused laser beams to achieve an effective coupling between the rotational state of a molecular ion and the electronic state of an atomic ion. In this setting, the atomic ion is used for read-out of the molecular ion state, in a manner analogous to quantum logic spectroscopy based on Raman transitions. In addition to high-precision spectroscopy, this setting allows for rotational ground state cooling, and can be considered as a candidate for the quantum information processing with polar molecular ions. All elements of our proposal can be realized with currently available technology.
Probabilistic state preparation of a single molecular ion by projection measurement
I. S. Vogelius,L. B. Madsen,M. Drewsen
Physics , 2005, DOI: 10.1088/0953-4075/39/19/S31
Abstract: 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.
Blackbody-radiation-assisted molecular laser cooling
I. S. Vogelius,L. B. Madsen,M. Drewsen
Physics , 2002, DOI: 10.1103/PhysRevLett.89.173003
Abstract: The translational motion of molecular ions can be effectively cooled sympathetically to temperatures below 100 mK in ion traps through Coulomb interactions with laser-cooled atomic ions. The distribution of internal rovibrational states, however, gets in thermal equilibrium with the typically much higher temperature of the environment within tens of seconds. We consider a concept for rotational cooling of such internally hot, but translationally cold heteronuclear diatomic molecular ions. The scheme relies on a combination of optical pumping from a few specific rotational levels into a ``dark state'' with redistribution of rotational populations mediated by blackbody radiation.
Observation of Three-dimensional Long-range Order in Smaller Ion Coulomb Crystals in an rf Trap
A. Mortensen,E. Nielsen,T. Matthey,M. Drewsen
Physics , 2005, DOI: 10.1103/PhysRevLett.96.103001
Abstract: Three-dimensional long-range ordered structures in smaller and near-spherically symmetric Coulomb crystals of ^{40}Ca^+ ions confined in a linear rf Paul trap have been observed when the number of ions exceeds ~1000 ions. This result is unexpected from ground state molecular dynamics (MD) simulations, but found to be in agreement with MD simulations of metastable ion configurations. Previously, three-dimensional long-range ordered structures have only been reported in Penning traps in systems of ~50,000 ions or more.
Rotational cooling of heteronuclear molecular ions with ^1-Sigma, ^2-Sigma, ^3-Sigma and ^2-Pi electronic ground states
I. S. Vogelius,L. B. Madsen,M. Drewsen
Physics , 2004, DOI: 10.1103/PhysRevA.70.053412
Abstract: The translational motion of molecular ions can be effectively cooled sympathetically to translational temperatures below 100 mK in ion traps through Coulomb interactions with laser-cooled atomic ions. The ro-vibrational degrees of freedom, however, are expected to be largely unaffected during translational cooling. We have previously proposed schemes for cooling of the internal degrees of freedom of such translationally cold but internally hot heteronuclear diatomic ions in the simplest case of ^1-Sigma electronic ground state molecules. Here we present a significant simplification of these schemes and make a generalization to the most frequently encountered electronic ground states of heteronuclear molecular ions: ^1-Sigma, ^2-Sigma, ^3-Sigma and ^2-Pi. The schemes are relying on one or two laser driven transitions with the possible inclusion of a tailored incoherent far infrared radiation field.
Rotational cooling of molecules using lamps
I. S. Vogelius,L. B. Madsen,M. Drewsen
Physics , 2004, DOI: 10.1088/0953-4075/37/22/015
Abstract: We investigate theoretically the application of tailored incoherent far-infrared fields in combination with laser excitation of a single rovibrational transition for rotational cooling of translationally cold polar diatomic molecules. The cooling schemes are effective on a timescale shorter than typical unperturbed trapping times in ion traps and comparable to obtainable confinement times of neutral molecules.
Rf-induced persistent long-range ordered structures in two-species ion Coulomb crystals in a linear Paul trap
A. Mortensen,E. Nielsen,T. Matthey,M. Drewsen
Physics , 2006,
Abstract: We report on the observations of three-dimensional long-range ordered structures in the central $^{40}$Ca$^+$ ion component of $^{40}$Ca$^+$--$^{44}$Ca$^+$ two-species ion Coulomb crystals in a linear Paul trap. In contrast to long-range ordering previously observed in single species crystals, the structures observed are strikingly persistent and always of one specific type in one particular orientation. Molecular dynamics simulations strongly indicate that these characteristics are a hitherto unpredicted consequence of the co-axial cylindrical symmetry of the central ion component of the Coulomb crystal and the radio frequency quadrupole trapping field.
Classical and Quantum Modes of Coupled Mathieu Equations
H. Landa,M. Drewsen,B. Reznik,A. Retzker
Mathematics , 2012, DOI: 10.1088/1751-8113/45/45/455305
Abstract: We expand the solutions of linearly coupled Mathieu equations in terms of infinite-continued matrix inversions, and use it to find the modes which diagonalize the dynamical problem. This allows obtaining explicitly the ('Floquet-Lyapunov') transformation to coordinates in which the motion is that of decoupled linear oscillators. We use this transformation to solve the Heisenberg equations of the corresponding quantum-mechanical problem, and find the quantum wavefunctions for stable oscillations, expressed in configuration-space. The obtained transformation and quantum solutions can be applied to more general linear systems with periodic coefficients (coupled Hill equations, periodically driven parametric oscillators), and to nonlinear systems as a starting point for convenient perturbative treatment of the nonlinearity.
Loading of large ion Coulomb crystals into a linear Paul trap incorporating an optical cavity for cavity QED studies
P. Herskind,A. Dantan,M. B. Langkilde-Lauesen,A. Mortensen,J. L. Sorensen,M. Drewsen
Physics , 2008, DOI: 10.1007/s00340-008-3199-8
Abstract: We report on the loading of large ion Coulomb crystals into a linear Paul trap incorporating a high-Finesse optical cavity (F~3200). We show that, even though the 3-mm diameter dielectric cavity mirrors are placed between the trap electrodes and separated by only 12 mm, it is possible to produce in situ ion Coulomb crystals containing more than 100.000 calcium ions of various isotopes and with lengths of up to several millimeters along the cavity axis. We show that the number of ions inside the cavity mode is in principle high enough to achieve strong collective coupling between the ion Coulomb crystal and the cavity field. The results thus represent an important step towards ion trap based Cavity Quantum ElectroDynamics (CQED) experiments using cold ion Coulomb crystals.
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