We present an all-optical method to load 174Yb atoms into a single layer of an optical trap near the surface of a solid immersion lens which improves the numerical aperture of a microscope system. Atoms are transported to a region 20 um below the surface using a system comprised by three optical dipole traps. The optical accordion technique is used to create a condensate and compress the atoms to a width of 120 nm and a distance of 1.8 um away from the surface. Moreover, we are able to verify that after compression the condensate behaves as a two-dimensional quantum gas.
We present a compact and robust setup to optically transport ultracold atoms over long distances. Using a focus-tunable Moire lens that has recently appeared on the market, we demonstrate transport of up to a distance of 465 mm. A transfer efficiency of 70% is achieved with negligible temperature change at 11 $mu$K. With its high thermal stability and low astigmatism, the Moire lens is superior to fluid-based varifocal lenses. It is much more compact and stable than a lens mounted on a linear translation stage, allowing for simplified experimental setups.
We report on an efficient production scheme for a large quantum degenerate sample of fermionic lithium. The approach is based on our previous work on narrow-line $ 2S_{1/2}rightarrow 3P_{3/2} $ laser cooling resulting in a high phase-space density of up to $3times10^{-4}$. This allows utilizing a large volume crossed optical dipole trap with a total power of $45,textrm{W}$, leading to high loading efficiency and $8times10^6$ trapped atoms. The same optical trapping configuration is used for rapid adiabatic transport over a distance of $25,textrm{cm}$ in $0.9,textrm{s}$, and subsequent evaporative cooling. With optimized evaporation we achieve a degenerate Fermi gas with $1.7times 10^{6}$ atoms at a temperature of $60 , textrm{nK}$, corresponding to $T/T_{text{F}}=0.16left(2 right)$. Furthermore, the performance is demonstrated by evaporation near a broad Feshbach resonance creating a molecular Bose-Einstein condensate of $3times10^5$ lithium dimers.
From the study of long-range-interacting systems to the simulation of gauge fields, open-shell Lanthanide atoms with their large magnetic moment and narrow optical transitions open novel directions in the field of ultracold quantum gases. As for other atomic species, the magneto-optical trap (MOT) is the working horse of experiments but its operation is challenging, due to the large electronic spin of the atoms. Here we present an experimental study of narrow-line Dysprosium MOTs. We show that the combination of radiation pressure and gravitational forces leads to a spontaneous polarization of the electronic spin. The spin composition is measured using a Stern-Gerlach separation of spin levels, revealing that the gas becomes almost fully spin-polarized for large laser frequency detunings. In this regime, we reach the optimal operation of the MOT, with samples of typically $3times 10^8$ atoms at a temperature of 15,$mu$K. The spin polarization reduces the complexity of the radiative cooling description, which allows for a simple model accounting for our measurements. We also measure the rate of density-dependent atom losses, finding good agreement with a model based on light-induced Van der Waals forces. A minimal two-body loss rate $betasim 2times10^{-11},$cm$^{3}$/s is reached in the spin-polarized regime. Our results constitute a benchmark for the experimental study of ultracold gases of magnetic Lanthanide atoms.
We demonstrate fluorescence microscopy of individual fermionic potassium atoms in a 527-nm-period optical lattice. Using electromagnetically induced transparency (EIT) cooling on the 770.1-nm D$_1$ transition of $^{40}$K, we find that atoms remain at individual sites of a 0.3-mK-deep lattice, with a $1/e$ pinning lifetime of $67(9),rm{s}$, while scattering $sim 10^3$ photons per second. The plane to be imaged is isolated using microwave spectroscopy in a magnetic field gradient, and can be chosen at any depth within the three-dimensional lattice. With a similar protocol, we also demonstrate patterned selection within a single lattice plane. High resolution images are acquired using a microscope objective with 0.8 numerical aperture, from which we determine the occupation of lattice sites in the imaging plane with 94(2)% fidelity per atom. Imaging with single-atom sensitivity and addressing with single-site accuracy are key steps towards the search for unconventional superfluidity of fermions in optical lattices, the initialization and characterization of transport and non-equilibrium dynamics, and the observation of magnetic domains.
We predict that an atomic Bose-Einstein condensate strongly coupled to an intracavity optical lattice can undergo resonant tunneling and directed transport when a constant and uniform bias force is applied. The bias force induces Bloch oscillations, causing amplitude and phase modulation of the lattice which resonantly modifies the site-to-site tunneling. For the right choice of parameters a net atomic current is generated. The transport velocity can be oriented oppositely to the bias force, with its amplitude and direction controlled by the detuning between the pump laser and the cavity. The transport can also be enhanced through imbalanced pumping of the two counter-propagating running wave cavity modes. Our results add to the cold atoms quantum simulation toolbox, with implications for quantum sensing and metrology.
M. Miranda
,A. Nakamoto
,Y. Okuyama
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(2012)
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"All-optical transport and compression of ytterbium atoms into the surface of a solid immersion lens"
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Mikio Kozuma
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