A surface-patterned chip as a strong source of ultracold atoms for quantum technologies

Abstract

. (2013) A surface-patterned chip as a strong source of ultracold atoms for quantum technologies. Nature Nanotechnology, 8 (5). pp. 321-324. Copyright © 2013 MacMillanA copy can be downloaded for personal non-commercial research or study, without prior permission or chargeThe content must not be changed in any way or reproduced in any format or medium without the formal permission of the copyright holder(s) Laser cooled atoms are central to modern precision measurements 1-6 . They are also increasingly important as an enabling technology for experimental cavity quantum electrodynamics 7,8 , quantum information processing 9-11 and matter wave interferometry 12 . Although significant progress has been made in miniaturising atomic metrological devices 13,14 , these are limited in accuracy by their use of hot atomic ensembles and buffer gases. Advances have also been made in producing portable apparatus that benefit from the advantages of atoms in the microKelvin regime 15,16 . However, simplifying atomic cooling and loading using microfabrication technology has proved difficult 17,18 . In this letter we address this problem, realising an atom chip that enables the integration of laser cooling and trapping into a compact apparatus. Our source delivers ten thousand times more atoms than previous magneto-optical traps with microfabricated optics and, for the first time, at sub-Doppler temperatures. Moreover, the same chip design offers a simple way to form stable optical lattices. These features, combined with the simplicity of fabrication and the ease of operation, make these new traps a key advance in the development of cold-atom technology for high-accuracy, portable measurement devices.

Two-dimensional grating magneto-optical trap

“…Prior work has shown that 2D + GMOT flux is maximal for laser intensities near 20 mW/cm 2 , while the 3D GMOT atom number saturates near 50 mW/cm 2 [18]. Both are significantly higher than the 11 mW/cm 2 produced by our laser system.…”

“…Custom non-directional etched gratings have been fabricated to this standard for the 3D GMOT [18,25,26], albeit with considerable design time and fabrication cost. Such gratings often require e-beam lithography for small (≈ 500 nm) feature sizes.…”

“…These successes have spurred interest in transitioning cold atom devices from the lab to more demanding environments [9][10][11][12][13][14][15][16][17]. Recently, a three dimensional grating magneto-optical trap (3D GMOT) was demonstrated that satisfies many needs of a deployable system [18][19][20]. Particularly, the GMOT increases optical access while reducing system size, weight, power, and cost compared to conventional techniques.…”

“…The 2D GMOT enables faster loading rates and higher atom number in the 3D GMOT by separating the source vapor from the experimental region. The resulting 3D GMOT shows comparable atom number scaling to standard six-beam MOT's [18] and is able to achieve sub-Doppler cooling [21].…”

Contributed Review: The feasibility of a fully miniaturized magneto-optical trap for portable ultracold quantum technology

“…Miniaturized pyramid MOTs, however, suffer from low atom capture rates due to the small volume in which the beams overlap 45,46 , significant backscatter making the atoms difficult to detect 47 , and the geometry making transfer of the atoms to magnetic surface traps non-trivial. A recently demonstrated ver- sion of the tetrahedral-MOT using a planar grating as a reflector (which we refer to as the 'G-MOT', see Figure 2) can capture a large number of atoms, has lower backscatter 48 , and can be easily integrated with atom chip structures 49 . Some disadvantages include the effect of the grating on the wavefronts and polarizations of the manipulation beams 50 , and added difficulty in situations which require several widely-spaced wavelengths.…”