arXiv subjects

D. Sahagun

Publications and source records attributed to D. Sahagun.

4 recordsLinked to original sources

arXiv2013

An ultra-bright atom laser

We present a novel, ultra-bright atom-laser and ultra-cold thermal atom beam. Using rf-radiation we strongly couple the magnetic hyperfine levels of 87Rb atoms in a magnetically trapped Bose-Einstein condensate. At low rf-frequencies gravity opens a small hole in the trapping potenital and a well collimated, extremely bright atom laser emerges from just below the condensate. As opposed to traditional atom lasers based on weak coupling, this technique allows us to outcouple atoms at an arbitrarily large rate. We demonstrate an increase in flux per atom in the BEC by a factor of sixteen compared to the brightest quasi-continuous atom laser. Furthermore, we produce by two orders of magnitude the coldest thermal atom beam to date (200 nK).

cond-mat.quant-gas↗

arXiv2005

Integrated optical components on atom chips

We report on the integration of small-scale optical components into silicon wafers for use in atom chips. We present an on-chip fibre-optic atom detection scheme that can probe clouds with small atom numbers. The fibres can also be used to generate microscopic dipole traps. We describe our most recent results with optical microcavities and show that single-atom detection can be realised on an atom chip. The key components have been fabricated by etching directly into the atom chip silicon substrate.

physics.atom-ph↗

arXiv2003

Cold atoms probe the magnetic field near a wire

A microscopic Ioffe-Pritchard trap is formed using a straight, current-carrying wire, together with suitable auxiliary magnetic fields. By measuring the distribution of cold rubidium atoms held in this trap, we detect a weak magnetic field component $ΔB_z$ parallel to the wire. This field is proportional to the current in the wire and is approximately periodic along the wire with period $λ=230 μ$m. We find that the decrease of this field with distance from the centre of the wire is well described by the Bessel function $K_1(2πy/λ)$, as one would expect for the far field of a transversely oscillating current within the wire.

cond-mat↗

arXiv2003

Thermally induced spin flips above an atom chip

We describe an experiment in which Bose-Einstein condensates and cold atom clouds are held by a microscopic magnetic trap near a room temperature metal wire 500 $μ$m in diameter. The ensemble of atoms breaks into fragments when it is brought close to the ceramic-coated aluminum surface of the wire, showing that fragmentation is not peculiar to copper surfaces. The lifetime for atoms to remain in the microtrap is measured over a range of distances down to $27 μ$m from the surface of the metal. We observe the loss of atoms from the microtrap due to spin flips. These are induced by radio-frequency thermal fluctuations of the magnetic field near the surface, as predicted but not previously observed.

quant-ph↗