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(Color online) Drawing of the vacuum system showing the effusive atomic source (oven), the metal shield used to prevent Li from coating the inside of the quartz cell, and the MOT position. The inset shows the 3D model of the oven.
Source publication
We report on a simple oven-loaded magneto-optical trap (MOT) apparatus for
the creation of both molecular Bose-Einstein condensates (mBEC) and degenerate
Fermi gases (DFGs) of lithium. The apparatus does not require a Zeeman slower
or a 2D MOT nor does it require any separation or differential pumping between
the effusive atom source and the scienc...
Contexts in source publication
Context 1
... of the cell is connected through a stain- less steel bellows and 6 inch conflat cross to a 20 L s −1 Varian StarCell ion pump and a SAES CapaciTorr NEG pump. The outer dimensions of the quartz cell are 30 mm × 30 mm × 100 mm with a 5 mm wall thickness. The effusive lithium oven is located 10 cm from the trapping region. A small beam shield (see Fig. 1) is situated be- tween the oven and the trapping region in order to shield the quartz cell walls from the direct output of the effu- sive oven. This configuration is similar to that reported in Ref. [38] with the exception that in this work the trap- ping light for lithium is single frequency and is not broad- ened in any way to ...
Context 2
... lithium oven, made of non-magnetic stainless steel, consists of a cylindrical reservoir (15 mm long, 7 mm inner diameter, 1 mm wall thickness) enclosed by a screw cap with a 1 mm hole (Fig. 1, inset). A supporting element is attached to the cap and is made of a non- magnetic alloy of nickel and chromium (80% nickel and 20% chromium). It serves as a mechanical support and electrical contact between the feedthru electrodes. Due to the thin profile of the leads (1 mm), it provides ohmic heating for the atomic reservoir when current is ...
Context 3
... and position of the MOT beams, the high and low power ODT beams and the lower magnetic coil relative to the glass cell. Not shown is the third MOT beam along the z-axis, the top magnetic coil and the small "gradient" coil placed inside and concentric to it. The atomic source is attached to the feedthrough on the right side of the image (see Fig. 1). For reference, gravity points in the −ˆ z direction and the x-y plane is parallel to the optical table ...
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We have realized Bose-Einstein condensation (BEC) of 87Rb in the F=2, m_F=2 hyperfine substate in a hybrid trap, consisting of a quadrupole magnetic field and a single optical dipole beam. The symmetry axis of the quadrupole magnetic trap coincides with the optical beam axis, which gives stronger axial confinement than previous hybrid traps. After...
We report a novel approach for preparing a Bose–Einstein condensate (BEC) of 87Rb atoms using an electro-pneumatically driven transfer of atoms into a quadrupole-Ioffe magnetic trap (QUIC trap). More than 5 × atoms from a magneto-optical trap are loaded into a spherical quadrupole trap and then transferred into an Ioffe trap by moving the Ioffe coi...
Citations
... As a result, experiments with enriched fermionic potassium do not use Zeeman slowers and almost exclusively rely on 2D MOTs [10] or double-stage MOTs [1] as a source of pre-cooled atoms. As opposed to other alkali species, single-chamber apparatuses are rarely used with 40 K, even though a single-chamber design with a source located near the trapping region has enabled studies of the BEC-BCS crossover regime with 6 Li [11]. In recent years, some efforts have been made to bypass the need for potassium enrichment. ...
We demonstrate the largest number of ⁴⁰ K atoms that has ever been cooled to deeply sub-Doppler temperatures in a single chamber apparatus without using an enriched source of potassium. With gray molasses cooling on the D 1 -line following a standard D 2 -line magneto-optical trap, we obtain 3×10 ⁵ atoms at 10(2) μK. We reach densities high enough to measure the temperature via absorption imaging using the time-of-flight method. We magnetically trap a mixture of m F =-3/2,-5/2 and -7/2 Zeeman states of the F=7/2 hyperfine ground state confining 5×10 ⁴ atoms with a lifetime of 0.6 s or ∼10 ³ atoms with a lifetime of 2.8 s - depending on whether the temperature of the potassium dispensers was chosen to maximize the atom number or the lifetime. The background pressure-limited lifetime of 0.6 s is a reasonable starting point for proof-of-principle experiments with atoms and/or molecules in optical tweezers as well as for sympathetic cooling with another species if transport to a secondary chamber is implemented.
Our results show that unenriched potassium can be used to optimize experimental setups containing ⁴⁰ K in the initial stages of their construction, which can effectively extend the lifetime of enriched sources needed for proper experiments. Moreover, demonstration of sub-Doppler cooling and magnetic trapping of a relatively small number of potassium atoms might influence experiments with laser cooled radioactive isotopes of potassium.
... As a result, experiments with enriched fermionic potassium do not use Zeeman slowers and almost exclusively rely on 2D MOTs 10 or double-stage MOTs 1 as a source of pre-cooled atoms. As opposed to other alkali species, single chamber apparatuses are rarely used with 40 K, even though a single chamber design with a source located near the trapping region has enabled studies of the BEC-BCS crossover regime with 6 Li 11 . In recent years some efforts have been made to bypass the need for potassium enrichment. ...
We report on reaching sub-Doppler temperatures of $^{40}$K in a single-chamber setup using a dispenser-based potassium source with natural (0.012$\%$ of $^{40}$K) isotopic composition. With gray molasses cooling on the $D_1$-line following a standard $D_2$-line magneto-optical trap, we obtain $3\times10^5$ atoms at $\sim$10~\textmu K. We reach densities high enough to measure the temperature via absorption imaging using the time-of-flight method. Directly after sub-Doppler cooling we pump atoms into the $F=7/2$ hyperfine ground state and transfer a mixture of $m_F=-3/2,-5/2$ and $-7/2$ Zeeman states into the magnetic trap. We trap $5\times10^4$ atoms with a lifetime of 0.6~s when the dispensers are heated up to maximize the atom number at a cost of deteriorated background gas pressure. When the dispensers have been off for a day and the magneto-optical trap loading rate has been increased by light induced atomic desorption we can magnetically trap $\sim$$10^3$ atoms with a lifetime of 2.8~s. The background pressure-limited lifetime of 0.6~s is a reasonable starting point for proof-of-principle experiments with atoms and/or molecules in optical tweezers as well as for sympathetic cooling with another species if transport to a secondary chamber is implemented. Our results show that unenriched potassium can be used to optimize experimental setups containing $^{40}$K in the initial stages of their construction, which can effectively extend the lifetime of enriched sources needed for proper experiments. Moreover, demonstration of sub-Doppler cooling and magnetic trapping of a relatively small number of potassium atoms might influence experiments with laser cooled radioactive isotopes of potassium.
... Ultracold molecules are mostly prepared by photoassociation (PA) [7] and magnetoassociation (MA) [8]. Recently, the research of ultracold diatomic molecules has been extended from alkali metal atom systems, such as homonuclear Cs 2 [9], Rb 2 [10,11], Li 2 [12,13] and heteronuclear LiCs [14,15], LiRb [16,17], RbCs [18,19], NaRb [20], NaK [21], KRb [22] to alkaline earth metal atom systems and rare earth metal atom systems, such as Sr 2 [23], CsYb [24], and Eu 2 [25]. In * Author to whom any correspondence should be addressed. ...
We investigate theoretically the formation of ultracold 39K87Rb molecules on the lowest vibrational level of singlet ground electronic X1Σ+ state via the Feshbach-optimized photoassociation. The probability density of colliding atomic pair at the short-range interatomic separation is significantly enhanced near Feshbach resonances. Due to the limitation of transition selection rule, the direct transition between singlet and triplet electronic states is forbidden. The electronic spin-orbit couplings between excited electronic states are used to transfer the population from the triplet electronic state to the singlet electronic state. By using the magnetic field and four laser pulses, the colliding 39K and 87Rb atoms near a magnetically induced Feshbach resonance are converted into the 39K87Rb molecule. The final population on the lowest vibrational level of the X1Σ+ state reaches 0.02126.
... However, restricting the orientation of the device is undesirable for future applications. Inserting a Ni mesh into the dispenser to wick the Li metal would prevent migration in all orientations [40,45] and improve the loading rate scaling to R ∝ B max 3 . ...
We demonstrate a compact (0.25 L) system for laser cooling and trapping atoms from a heated dispenser source. Our system uses a nanofabricated diffraction grating to generate a magneto-optical trap (MOT) using a single input laser beam. An aperture in the grating allows atoms from the dispenser to be loaded from behind the chip, increasing the interaction distance of atoms with the cooling light. To take full advantage of this increased distance, we extend the magnetic field gradient of the MOT to create a Zeeman slower. The MOT traps approximately 106Li7 atoms emitted from an effusive source with loading rates greater than 106s−1. Our design is portable to a variety of atomic and molecular species and could be a principal component of miniaturized cold-atom-based technologies.
... The intermediate state jei was the v 0 20, N 0 1 level in the triplet c1 3 Σ g potential [18]. The Feshbach molecules are formed by first laser cooling 6 Li atoms in a Zeeman slower loaded magneto-optical trap (MOT) [19], then transferring them into an optical dipole trap [20] and performing forced evaporative cooling at 755 G where Feshbach molecules form once the ensemble temperature drops below the binding energy. Starting from results on photo-association to states in the c1 3 Σ g potential [18] and dark-state spectroscopy to the a 3 Σ u state [21], we performed spectroscopy of the same levels at 755 G as a prerequisite for the population transfer we demonstrate here. ...
Phase noise reduction in an optical phase-locked loop is investigated using an acousto-optic actuator external to the laser cavity and primary stabilization lock. This method does not require modification of the laser cavity or primary lock and is compatible with continuous frequency tuning schemes for a laser locked to a femto-second frequency comb [J. Opt. Soc. Am. B 26, 1276 (2009)JOBPDE0740-322410.1364/JOSAB.26.001276; Opt. Lett. 40, 4372 (2015)OPLEDP0146-959210.1364/OL.40.004372]. We achieve a cross-over frequency of 275 kHz and we demonstrate a single side band phase noise of − 92 dBc / Hz at a 10 kHz offset. Using two independently tunable lasers equipped with this locking system, we demonstrate quantum state manipulation of ultra-cold Li 6 dimers using stimulated Raman adiabatic passage.
... With subsequent operations, we have noticed further decreases in the AMD resistance at the 1 % level, and noticed a small accumulation of Li outside the slit of the tube. A thin Ni mesh inside the tube could be used to wick the Li in a future design 16 . ...
We demonstrate and characterize a source of Li atoms made from direct metal laser sintered titanium. The source's outgassing rate is measured to be $5 \,(2)\cdot 10^{-7}$\,$\rm{Pa}~ \rm{L}~ \rm{s}^{-1}$ at a temperature $T=330\,^\circ$C, which optimizes the number of atoms loaded into a magneto-optical trap. The source loads $\approx 10^7$ $^7$Li atoms in the trap in $\approx 1$\,s. The loaded source weighs 700\,mg and is suitable for a number of deployable sensors based on cold atoms.
... To increase the visibility of the bimodal density distribution, which is characteristic for the onset of Bose-Einstein condensation, the interaction strength between the molecules is lowered by linearly reducing the magnetic field to 690 G in 100 ms before TOF absorption imaging [6,31]. This reduces the atomic scattering length a 12 to around 1400 a 0 , which is related to the molecular s-wave scattering length via a mol = 0.6 a 12 [32]. ...
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 $3\times10^{-4}$. This allows utilizing a large volume crossed optical dipole trap with a total power of $45\,\textrm{W}$, leading to high loading efficiency and $8\times10^6$ 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 $1.7\times 10^{6}$ atoms at a temperature of $60 \, \textrm{nK}$, corresponding to $T/T_{\text{F}}=0.16\left(2 \right)$. Furthermore, the performance is demonstrated by evaporation near a broad Feshbach resonance creating a molecular Bose-Einstein condensate of $3\times10^5$ lithium dimers.
... 42,43 However, such an approach has proven successful in the production of degenerate gases of 6 Li. 44 By placing the atomic oven further away from the trapping region, differential pumping techniques can be used to reduce the contribution of the background pressure in the trapping region due to the hot atomic sources. To offset the reduction in the trappable atom flux resulting from moving the oven away from the MOT, a Zeeman slowing stage is used to slow fast moving atoms to a velocity which can be captured by the trap. ...
... Second, the decreasing magnetic field of the slower can be mated with the magnetic field from the quadrupole coils of the MOT such that the slower length can be made significantly shorter as the atoms complete the final stage of slowing after entering the MOT trapping region. Using the MOT field to provide slowing has been used in our previous experimental apparatus 44 and in similar dual species slowers. 29 Critical to the success of our design, where the end of the slower and the MOT region are not in close proximity (required for smooth field matching between the end of the slower and the MOT region as demonstrated previously 29 ), is our use of a coil at the end of the slower to produce a magnetic field with opposite polarity to disengage atoms from the slower by violating the adiabatic slowing condition. ...
We present a dual-species effusive source and Zeeman slower designed to produce slow atomic beams of two elements with a large mass difference and with very different oven temperature requirements. We demonstrate this design for the case of (6)Li and (85)Rb and achieve magneto-optical trap (MOT) loading rates equivalent to that reported in prior work on dual species (Rb+Li) Zeeman slowers operating at the same oven temperatures. Key design choices, including thermally separating the effusive sources and using a segmented coil design to enable computer control of the magnetic field profile, ensure that the apparatus can be easily modified to slow other atomic species. By performing the final slowing using the quadrupole magnetic field of the MOT, we are able to shorten our Zeeman slower length making for a more compact system without compromising performance. We outline the construction and analyze the emission properties of our effusive sources. We also verify the performance of the source and slower, and we observe sequential loading rates of 12 × 10(8) atoms/s for a Rb oven temperature of 140 °C and 1.1 × 10(8) atoms/s for a Li reservoir at 460 °C, corresponding to reservoir lifetimes for continuous operation of 10 and 4 years, respectively.
... Having dispensers or atomic ovens close to the trapping region can result in higher background pressures that limit the trap lifetime and thus the achievable atom number in the MOT [41,42]. However, such an approach has proven successful in the production of degenerate gases of 6 Li [43]. ...
... Second, the decreasing magnetic field of the slower can be mated with the magnetic field from the quadrupole coils of the MOT such that the slower length can be made significantly shorter as the atoms complete the final stage of slowing after entering the MOT trapping region. Using the MOT field to provide slowing has been used in our previous experimental apparatus [43] and in similar dual species slowers [29]. ...
We present a dual-species effusive source and Zeeman slower capable of
producing slow atomic beams of two elements with a large mass difference, and
we realize this design to slow and load $^6$Li and $^{85}$Rb into a
magneto-optical trap. Key design choices, such as separating the effusive
sources and allowing for the computer control of the magnetic field profile,
ensure that the apparatus can be easily modified to facilitate the cooling of
alternative atomic species making it applicable for a variety of cold atom
experiments. By utilizing the quadrupole magnetic field of the magneto-optic
trap as a secondary slowing field, we are able to shorten our Zeeman slower
making for a more compact and robust system without compromising performance.
Secondary slowing by the MOT trapping field is optimized by tuning the exit
speed of atoms from the Zeeman slower through the use of a disengagement coil.
We outline the construction and analyze the emission properties of our effusive
sources. Finally, we verify the performance of the source and slower by
measuring the loading rate and steady state atom number of a magneto-optical
trap of both species. We achieve a maximum loading rate of $3.5 \times
10^8~$atoms/s for Rb and $2 \times 10^7~$atoms/s for Li, consistent with the
expected performance of the slower at the operational temperatures of the
effusive sources.
... Panel c of Fig. 4 shows how we incorporated two of these field plates into our laser cooling apparatus described in [20] [21]. Although we experienced a loss of power due to reflections from the transparent substrates (which were not AR coated) and the ITO substrate (the transmission around 670 nm and 780 nm is about 80%), we did not experience any significant decrease in the MOT performance. ...
We present a design and characterization of optically transparent electrodes
suitable for atomic and molecular physics experiments where high optical access
is required. The electrodes can be operated in air at standard atmospheric
pressure and do not suffer electrical breakdown even for electric fields far
exceeding the dielectric breakdown of air. This is achieved by putting an ITO
coated dielectric substrate inside a stack of dielectric substrates, which
prevents ion avalanche resulting from Townsend discharge. With this design, we
observe no arcing for fields of up to 120 kV/cm. Using these plates, we
directly verify the production of electric fields up to 18~kV/cm inside a
quartz vacuum cell by a spectroscopic measurement of the dc Stark shift of the
$5^2S_{1/2} \rightarrow 5^2P_{3/2}$ transition for a cloud of laser cooled
Rubidium atoms. We also report on the shielding of the electric field and
residual electric fields that persist within the vacuum cell once the
electrodes are discharged. In addition, we discuss observed atom loss that
results from the motion of free charges within the vacuum. The observed
asymmetry of these phenomena on the bias of the electrodes suggests that field
emission of electrons within the vacuum is primarily responsible for these
effects and may indicate a way of mitigating them.
