| 1. |
- Braaten, E., et al.
(författare)
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Efimov physics in Li-6 atoms
- 2010
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 81:1
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Tidskriftsartikel (refereegranskat)abstract
- A new narrow three-atom loss resonance associated with an Efimov trimer crossing the three-atom threshold has recently been discovered in a many-body system of ultracold Li-6 atoms in the three lowest hyperfine spin states at a magnetic field near 895 G. O'Hara and coworkers have used measurements of the three-body recombination rate in this region to determine the complex three-body parameter associated with Efimov physics. Using this parameter as the input, we calculate the universal predictions for the spectrum of Efimov states and for the three-body recombination rate in the universal region above 600 G where all three scattering lengths are large. We predict an atom-dimer loss resonance at 672 +/- 2G associated with an Efimov trimer disappearing through an atom-dimer threshold. We also predict an interference minimum in the three-body recombination rate at 759 +/- 1G where the three-spin mixture may be sufficiently stable to allow experimental study of the many-body system.
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| 2. |
- Braaten, E., et al.
(författare)
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Renormalization in the three-body problem with resonant p-wave interactions
- 2012
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 86:1
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Tidskriftsartikel (refereegranskat)abstract
- Resonant p-wave interactions can be described by a minimal zero-range model defined by a truncated effective range expansion so that the only two-body interaction parameters are the inverse scattering volume 1/a(p) and the p-wave effective range r(p). This minimal model can be formulated as a local quantum field theory with a p-wave interaction between atom fields and a molecular field. In the two-atom sector, the model is renormalizable, but it has unphysical behavior at high energies because there are negative-probability states with momentum scale r(p). In the sector with three atoms, two of which are identical, renormalization in some parity and angular momentum channels involves an ultraviolet limit cycle, indicating asymptotic discrete scale invariance. The Efimov effect occurs in the unitary limit a(p)(-1/3),r(p) -> 0, but this limit is unphysical because there are low-energy states with negative probability. The minimal model can be of physical relevance only at energies small compared to the energy scale set by r(p) where the effects of negative-probability states are suppressed.
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| 3. |
- Cattani, F., et al.
(författare)
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Co-propagating Bose-Einstein condensates and electromagnetic radiation: Emission of mutually localized structures
- 2011
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 83:1, s. 013608-
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the details of the formation of mutually guided and localized structures of co-propagating coherent electromagnetic radiation and a Bose-Einstein condensate (BEC). In the limit of zero temperature and large detuning, we have used a semiclassical model based on Maxwell equations coupled to the Schrodinger equation which includes the back action of the atoms on the radiation. Following numerically the two systems, we have found that a variety of effects can be displayed depending on the initial conditions: The formation of single-hump mutually guided structures of atoms and radiation seems to be only one of the possible outcomes of the interaction. Other effects we have observed via numerical simulations are, for instance, the creation of atom-laser solitarylike structures which are then symmetrically ejected from the initial central peak or similar symmetrical structures trapped in a bound state and thus oscillating about the central point in a way somehow reminiscent of purely nonlinear optics effect.
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| 4. |
- Cattani, F., et al.
(författare)
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Interacting laser and Bose-Einstein-condensate atomic beams: Mutual guiding structures
- 2010
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 81:4, s. 043623 -
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Tidskriftsartikel (refereegranskat)abstract
- A basic set of equations describing the interaction of a Bose-Einstein condensate (BEC) with a laser field is derived based on a semiclassical model and applied to the problem of mutual guiding of laser and BEC atomic beams. Within this framework we have studied stationary spatially localized solutions of the nonlinear system which describe possible laser and BEC atomic beam guiding and have shown their stability as well. It is also shown that a self-guiding effect can be realized through both single-and multiple-scaled structures of a BEC atomic and a laser beam.
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| 5. |
- Clemente, P., et al.
(författare)
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Single-pixel digital ghost holography
- 2012
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 86:4
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Tidskriftsartikel (refereegranskat)abstract
- Since its discovery, the "ghost" diffraction phenomenon has emerged as an unconventional technique for optical imaging with very promising advantages. However, extracting the intensity and phase information of a structured and realistic object remains a challenge. Here we show that a ghost hologram can be recorded with a single-pixel configuration by adapting concepts from standard digital holography. The presented homodyne scheme enables phase imaging with nanometric depth resolution and three-dimensional focusing ability and shows a high signal-to-noise ratio.
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| 6. |
- Frisk Kockum, Anton, 1987, et al.
(författare)
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Designing frequency-dependent relaxation rates and Lamb shifts for a giant artificial atom
- 2014
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 90:1, s. 013837-
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Tidskriftsartikel (refereegranskat)abstract
- In traditional quantum optics, where the interaction between atoms and light at optical frequencies is studied, the atoms can be approximated as pointlike when compared to the wavelength of light. So far, this relation has also been true for artificial atoms made out of superconducting circuits or quantum dots, interacting with microwave radiation. However, recent and ongoing experiments using surface acoustic waves show that a single artificial atom can be coupled to a bosonic field at several points wavelengths apart. Here, we theoretically study this type of system. We find that the multiple coupling points give rise to a frequency dependence in the coupling strength between the atom and its environment and also in the Lamb shift of the atom. The frequency dependence is given by the discrete Fourier transform of the coupling-point coordinates and can therefore be designed. We discuss a number of possible applications for this phenomenon, including tunable coupling, single-atom lasing, and other effects that can be achieved by designing the relative coupling strengths of different transitions in a multilevel atom.
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| 7. |
- Frisk Kockum, Anton, 1987, et al.
(författare)
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Undoing measurement-induced dephasing in circuit QED
- 2012
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 85:5
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the backaction of homodyne detection and photodetection on superconducting qubits in circuit quantum electrodynamics. Although both measurement schemes give rise to backaction in the form of stochastic phase rotations, which leads to dephasing, we show that this can be perfectly undone provided that the measurement signal is fully accounted for. This result improves on an earlier one [Phys. Rev. A 82, 012329 (2010)], showing that the method suggested can be made to realize a perfect two-qubit parity measurement. We propose a benchmarking experiment on a single qubit to demonstrate the method using homodyne detection. By analyzing the limited measurement efficiency of the detector and bandwidth of the amplifier, we show that the parameter values necessary to see the effect are within the limits of existing technology.
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| 8. |
- Hammer, H. W., et al.
(författare)
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Efimov physics in atom-dimer scattering of Li-6 atoms
- 2010
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 82:2
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Tidskriftsartikel (refereegranskat)abstract
- Li-6 atoms in the three lowest hyperfine states display universal properties when the S-wave scattering length between each pair of states is large. Recent experiments reported four pronounced features arising from Efimov physics in the atom-dimer relaxation rate, namely two resonances and two local minima. We use the universal effective-field theory to calculate the atom-dimer relaxation rate at zero temperature. Our results describe the four features qualitatively and imply there is a hidden local minimum. In the vicinity of the resonance at 685 G, we perform a finite temperature calculation which improves the agreement of theory and experiment. We conclude that finite temperature effects cannot be neglected in the analysis of the experimental data.
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| 9. |
- Hansson, Tobias, 1983, et al.
(författare)
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Bichromatically pumped microresonator frequency combs
- 2014
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 90:1
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Tidskriftsartikel (refereegranskat)abstract
- A study is made of the nonlinear dynamics of bichromatically pumped microresonator Kerr frequency combs described by a driven and damped nonlinear Schrodinger equation, with an additional degree of freedom in the form of the modulation frequency. A truncated four-wave model is derived for the pump modes and the dominant sideband pair, which is found to be able to describe much of the essential dynamical behavior of the full equation. The stability of stationary states within the four-wave model is investigated, and numerical simulations are made to demonstrate that a large range of solutions, including cavity solitons, are possible beyond previously considered low-intensity patterns.
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| 10. |
- Johansson, J. R., et al.
(författare)
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Nonclassical microwave radiation from the dynamical Casimir effect
- 2013
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 87:4, s. Art. no. 043804-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate quantum correlations in microwave radiation produced by the dynamical Casimir effect in a superconducting waveguide terminated and modulated by a superconducting quantum interference device. We apply nonclassicality tests and evaluate the entanglement for the predicted field states. For realistic circuit parameters, including thermal background noise, the results indicate that the produced radiation can be strictly nonclassical and can have a measurable amount of intermode entanglement. If measured experimentally, these nonclassicality indicators could give further evidence of the quantum nature of the dynamical Casimir radiation in these circuits.
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