Making an ultracold gas

We provide an introduction to the experimental physics of quantum gases. At the low densities of ultracold quantum gases, confinement can be understood from single-particle physics, and interactions can be understood from two-body physics. The structure of atoms provides resonances both in the optical domain and in the radio-frequency domain. Atomic structure data is given for the 27 atomic isotopes that had been brought to quantum degeneracy at the time this chapter was written. We discuss the motivations behind choosing among these species. We review how static and oscillatory fields are treated mathematically. An electric dipole moment can be induced in a neutral atom, and is the basis for optical manipulation as well as short-range interactions. Many atoms have permanent magnetic dipole moments, which can be used for trapping or long-range interactions. The Toronto $^{40}$K/$^{87}$Rb lattice experiment provides an illustration of how these tools are combined to create an ultracold, quantum-degenerate gas.Comment: 16 pages, 2 figures. New version includes corrections, improved format, and hyperlinked references. To appear as Chapter 2 in "Quantum gas experiments - exploring many-body states," P. Torma, K. Sengstock, eds. (Imperial College Press, 2014

Universal Relations for a Fermi Gas Close to a p-Wave Interaction Resonance

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Momentum spectroscopy of 1D phase fluctuations in Bose-Einstein condensates

We measure the axial momentum distribution of Bose-Einstein condensates with an aspect ratio of 152 using Bragg spectroscopy. We observe the Lorentzian momentum distribution characteristic of one-dimensional phase fluctuations. The temperature dependence of the width of this distribution provides a quantitative test of quasi-condensate theory. In addition, we observe a condensate length consistent with the absence of density fluctuations, even when phase fluctuations are large.Comment: 4 pages, 3 figures; submitted to Phys. Rev. Let

Atom lithography using MRI-type feature placement

We demonstrate the use of frequency-encoded light masks in neutral atom lithography. We demonstrate that multiple features can be patterned across a monotonic potential gradient. Features as narrow as 0.9 microns are fabricated on silicon substrates with a metastable argon beam. Internal state manipulation with such a mask enables continuously adjustable feature positions and feature densities not limited by the optical wavelength, unlike previous light masks.Comment: 4 pages, 4 figure

Momentum Spectroscopy of Phase Fluctuations of an Elongated Bose-Einstein Condensate

We have measured the momentum distribution of an elongated BEC (aspect ratio of 152), for temperatures below the critical temperature. The corresponding coherence length is significantly smaller than the condensate length in a wide range of temperature, in quantitative agreement with theoretical predictions. The Lorentzian shape of the momentum spectrum supports the image of a phase fluctuating quasicondensate.Comment: Proceedings of the International Conference on Laser Spectroscopy (ICOLS 03), Cairns, Australia, july 200

Interference of a Tonks-Girardeau Gas on a Ring

We study the quantum dynamics of a one-dimensional gas of impenetrable bosons on a ring, and investigate the interference that results when an initially trapped gas localized on one side of the ring is released, split via an optical-dipole grating, and recombined on the other side of the ring. Large visibility interference fringes arise when the wavevector of the optical dipole grating is larger than the effective Fermi wavevector of the initial gas.Comment: 7 pages, 3 figure