Demagnetization cooling of a gas

Fattori, M.; Koch, Tobias; Goetz, Stefan M.; Griesmaier, Axel; Hensler, S.; Stühler, J.; Pfau, Tilman

doi:10.1038/nphys443

Cited by 75 publications

(88 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A 5 mK deep dipole trap for Dy could be constructed using 200 mW of 420-nm light (available from a doubled Ti:Al 2 O 3 laser), detuned two THz from the J = 1 transition and focused to a 30-µm waist, having an absorption rate of 400 s −1 . Once in an optical trap, efficient cooling could be achieved using evaporative or demagnetization cooling [36]. The large calculated inelastic cross section for Ho would make evaporative cooling of magnetically trapped Ho even more difficult; we were unable to achieve any adiabatic cooling of this atom.…”

Section: Discussionmentioning

confidence: 99%

Magnetic relaxation in dysprosium-dysprosium collisions

Newman

Brahms

et al. 2011

Phys. Rev. A

View full text Add to dashboard Cite

The collisional magnetic reorientation rate constant g R is measured for magnetically trapped atomic dysprosium (Dy), an atom with large magnetic dipole moments. Using buffer gas cooling with cold helium, large numbers (>10 11 ) of Dy are loaded into a magnetic trap and the buffer gas is subsequently removed. The decay of the trapped sample is governed by collisional reorientation of the atomic magnetic moments. We find g R = 1.9 ± 0.5 × 10 −11 cm 3 s −1 at 390 mK. We also measure the magnetic reorientation rate constant of holmium (Ho), another highly magnetic atom, and find g R = 5 ± 2 × 10 −12 cm 3 s −1 at 690 mK. The Zeeman relaxation rates of these atoms are greater than expected for the magnetic dipole-dipole interaction, suggesting that another mechanism, such as an anisotropic electrostatic interaction, is responsible. Comparison with estimated elastic collision rates suggests that Dy is a poor candidate for evaporative cooling in a magnetic trap.

show abstract

Section: Discussionmentioning

confidence: 99%

Magnetic relaxation in dysprosium-dysprosium collisions

Newman

Brahms

et al. 2011

Phys. Rev. A

View full text Add to dashboard Cite

show abstract

“…Cooling schemes which rely on the anisotropic nature of dipolar interaction have been experimentally demonstrated for both bosons and fermions. Dipolar anisotropy connects different angular momentum channels resulting in coupling between translational and spin degrees of freedom which has been used for depolarization cooling [29], demagnetization cooling [30], and * brenklioglu@bilkent.edu.tr more recently spin distillation [31] for bosons. In addition, universal dipolar scattering which relies both on the anisotropy and the long range of interaction has been used to cool a single component Fermi gas to degeneracy [32].…”

Section: Introductionmentioning

confidence: 99%

Heat transfer through dipolar coupling: Sympathetic cooling without contact

2016

View full text Add to dashboard Cite

We consider two parallel layers of dipolar ultracold Fermi gases at different temperatures and calculate the heat transfer between them. The effective interactions describing screening and correlation effects between the dipoles in a single layer are modeled within the Euler-Lagrange Fermihypernetted chain approximation. The random-phase approximation is used for the interactions across the layers. We investigate the amount of transferred power between the layers as a function of the temperature difference. Energy transfer arises due to the long-range dipole-dipole interactions. A simple thermal model is established to investigate the feasibility of using the contactless sympathetic cooling of the ultracold polar atoms/molecules. Our calculations indicate that dipolar heat transfer is effective for typical polar molecule experiments and may be utilized as a cooling process.

show abstract

“…Our scheme differs from single-shot adiabatic demagnetization refrigeration (including that demonstrated in a gas of chromium atoms [31]) in that the magnetic field is replaced by a magnetic field gradient, and spin flip collisions by spin transport. The chromium scheme cannot be applied to alkali atoms due to the much slower spin-flip rates, and extending it from microkelvins to picokelvins would require sub-microgauss magnetic field control.…”

mentioning

confidence: 99%

Spin Gradient Demagnetization Cooling of Ultracold Atoms

et al. 2011

View full text Add to dashboard Cite

We demonstrate a new cooling method in which a time-varying magnetic field gradient is applied to an ultracold spin mixture. This enables preparation of isolated spin distributions at positive and negative effective spin temperatures of ±50 picokelvin. The spin system can also be used to cool other degrees of freedom, and we have used this coupling to cool an apparently equilibrated Mott insulator of rubidium atoms to 350 picokelvin. These are the lowest temperatures ever measured in any system. The entropy of the spin mixture is in the regime where magnetic ordering is expected.

show abstract

Demagnetization cooling of a gas

Cited by 75 publications

References 27 publications

Magnetic relaxation in dysprosium-dysprosium collisions

Magnetic relaxation in dysprosium-dysprosium collisions

Heat transfer through dipolar coupling: Sympathetic cooling without contact

Spin Gradient Demagnetization Cooling of Ultracold Atoms

Contact Info

Product

Resources

About