Optically plugged quadrupole trap for Bose-Einstein condensates

Naik, Devang; Raman, Chandra

doi:10.1103/physreva.71.033617

Cited by 39 publications

(54 citation statements)

References 21 publications

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“…Hybrid traps, realized by the addition of either a blue [11,12] or red [13] detuned laser beam to the quadrupole potential, could present an alternative to the solution presented here in the context of a moving-coil magnetic transporter. However, retaining the ability to produce condensates in an alignment-free configuration seems advantageous for stable day-to-day operation.…”

Section: Introductionmentioning

confidence: 99%

Versatile transporter apparatus for experiments with optically trapped Bose–Einstein condensates

Pertot

Greif²,

Albert

et al. 2009

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. We describe a versatile and simple scheme for producing magnetically and optically-trapped 87 Rb Bose-Einstein condensates, based on a moving-coil transporter apparatus. The apparatus features a TOP trap that incorporates the movable quadrupole coils used for magneto-optical trapping and long-distance magnetic transport of atomic clouds. As a stand-alone device, this trap allows for the stable production of condensates containing up to one million atoms. In combination with an optical dipole trap, the TOP trap acts as a funnel for efficient loading, after which the quadrupole coils can be retracted, thereby maximizing optical access. The robustness of this scheme is illustrated by realizing the superfluid-to-Mott insulator transition in a three-dimensional optical lattice.

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Section: Introductionmentioning

confidence: 99%

Versatile transporter apparatus for experiments with optically trapped Bose–Einstein condensates

Pertot

Greif²,

Albert

et al. 2009

J. Phys. B: At. Mol. Opt. Phys.

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“…Compared to many other kinds of traps, the optically-plugged magnetic quadrupole (OPQ) trap has many advantages, which has been demonstrated in some groups [3,[22][23][24][25]. First, the tight confinement allows for fast radio frequency (RF) evaporative cooling and the large trapping volume offered by the magnetic quadrupole trap facilitates loading of a large number of atoms from the magneto-optical trap (MOT).…”

mentioning

confidence: 99%

“…Different kinds of external traps have been used to confine ultracold atoms where evaporative cooling is applied as a final stage to cool atoms into degeneracy, such as time-orbiting potential (TOP) magnetic trap [1], quadrupole and Ioffe configuration (QUIC) magnetic trap [18], all optical trap [19,20], and magneto-optical combination trap [21]. Compared to many other kinds of traps, the optically-plugged magnetic quadrupole (OPQ) trap has many advantages, which has been demonstrated in some groups [3,[22][23][24][25]. First, the tight confinement allows for fast radio frequency (RF) evaporative cooling and the large trapping volume offered by the magnetic quadrupole trap facilitates loading of a large number of atoms from the magneto-optical trap (MOT).…”

mentioning

confidence: 99%

Production of Rubidium Bose—Einstein Condensate in an Optically Plugged Magnetic Quadrupole Trap

Zhang

Gao

Kong

et al. 2016

Chinese Phys. Lett.

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We have experimentally produced rubidium Bose-Einstein condensate in an optically-plugged magnetic quadrupole (OPQ) trap. A far blue-detuned focused laser beam with a wavelength of 532 nm is plugged in the center of the magnetic quadrupole trap to increase the number of trapped atoms and suppress the heating. A radio frequency (RF) evaporative cooling in the magneto-optical hybrid trap is applied to decrease the atom temperature into degeneracy. The atom number of the condensate is 1.2(0.4)×105 and the temperature is below 100 nK. We have also studied characteristic behaviors of the condensate, such as phase space density (PSD), condensate fraction and anisotropic expansion.PACS numbers: 67.10.Ba; 64.70.fm; 37.10.De Since the experimental observation of Bose-Einstein condensate (BEC) in a dilute gas [1][2][3], the ultracold quantum gas has become a reachable tabletop to carry on a wide range of research, such as accurate measurement on physical constants [4,5] [19,20], and magneto-optical combination trap [21]. Compared to many other kinds of traps, the optically-plugged magnetic quadrupole (OPQ) trap has many advantages, which has been demonstrated in some groups [3,[22][23][24][25]. First, the tight confinement allows for fast radio frequency (RF) evaporative cooling and the large trapping volume offered by the magnetic quadrupole trap facilitates loading of a large number of atoms from the magneto-optical trap (MOT). Secondly, the atom cloud is positioned exactly in the center of the glass cell on the symmetry axis of the quadrupole coil pair, which ensures very good optical access to atoms. Third, the quadrupole coil pair allows to create large homogeneous magnetic fields by switching to copropagating currents, which we can use to address Feshbach resonances.In this paper, we produce rubidium BEC in an OPQ trap. Here we show that the laser beam with a wavelength of 532 nm can be used to efficiently obtain 87 Rb BEC despite the large detuning of the optical plug laser * Electronic address: kjjiang@wipm.ac.cn from the rubidium transition line at 780 nm. The atom number of the condensate is 1.2(0.4) × 10 5 and the temperature is less than 100 nK, which matches the basic requirements for further advanced studies. We have also studied characteristic behaviors of the condensate, such as phase space density (PSD), condensate fraction and anisotropic expansion. In the near future we will use the obtained rubidium BEC to study the collective oscillations of the quantum gas, and generate an ultracold Bose-Femi mixture using the sympathetic cooling in the same experimental setup where we have cooled fermionic atoms like 6 Li and 40 K [26,27].We use the two-MOTs configuration to realize 87 Rb BEC. The optical arrangement is shown in Fig.1. Two diode lasers (DLs) are individually frequency locked on the two crossover transitions |F = 1 → |F ′ = 1, 2 and |F = 2 → |F ′ = 2, 3 , respectively, using the standard saturation absorption spectroscopy (SAS) method. DL2 affords cooling, probing and pushing beams, after passing...

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“…For example, assume a spin-1 condensate in a QT plus an "optical plug" [8] satisfies V o (ρ, z) = V o (ρ, −z), then we find C = 0 and s = 0 due to the spatial reflection symmetry about the x − y plane. The ground state components ψ (z) ±1 ( r) g then automatically carry persistent currents with winding numbers ∓1 according to Eq.…”

mentioning

confidence: 99%

“…In cylindrical coordinate (ρ, φ, z), the B-field of a QT is expressed as B( r) = B ′ (ρê ρ − 2zê z ). An optical potential V o (ρ, z) is introduced to push atoms away from the region of small B( r), eliminating the deadly Majorona transitions [7,8]. Because this B-field is cylindrically symmetric, F ·n( r) commutes with the z-component of the total atomic angular momentum J z = L z + F z .…”

mentioning

confidence: 99%

Angular Momentum of a Magnetically Trapped Atomic Condensate

et al. 2007

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For an atomic condensate in an axially symmetric magnetic trap, the sum of the axial components of the orbital angular momentum and the hyperfine spin is conserved. Inside an Ioffe-Pritchard trap (IPT) whose magnetic field (B-field) is not axially symmetric, the difference of the two becomes surprisingly conserved. In this paper we investigate the relationship between the values of the sum or difference angular momentums for an atomic condensate inside a magnetic trap and the associated gauge potential induced by the adiabatic approximation. Our result provides significant new insight into the vorticity of magnetically trapped atomic quantum gases. [3]. The direction of the Bfield forming the magnetic trap is generally a function of the spatial position. For a trapped atom, its hyperfine spin adiabatically follows the changing B-field direction, and the atom remains aligned (or anti-aligned) with respect to the local B-field. As a result of the adiabatic approximation, the center of mass motion of a magnetically trapped atom experiences an induced gauge potential from the changing B-field [4,5].In a variety of magnetic traps, e.g., in a QT, the B-field is invariant with respect to rotations along a fixed z-axis. As the cse of single particle dynamics [6], such a SO(2) symmetry leads to the conservation of the z-component J z (= L z + F z ) of the total angular momentum or the sum of the z-components of the atomic spatial angular momentum L and the hyperfine spin F . A different symmetry exists for an IPT giving rise to a corresponding conserved quantity D z (= L z − F z ), the difference of L z and F z . To our knowledge, this surprising property has never before been identified explicitly. We thus feel obliged to present this letter because it significantly affects the vortical properties of a global condensate ground state in a magnetic trap.Our work is focused on a detailed investigation of the relationship between the gauge potential and the associated values of J z (D z ) in a magnetic trap. For a spin-F condensate, due to the appearance of the adiabatic gauge potential, the possible values of J z or D z are restricted to a definite region [−F, F ]. The gauge potential of our formulation is directly related to the effective trap rotation studied earlier in Ref. [5]. While Ho and Shenoy mainly studied the orbital angular momentum component in an IPT [5], instead we concentrate on the conserved quantity, the sum (J z ) or difference (D z ) for a QT or a IPT. This paper is organized as follows. We first consider a spin-1 condensate in a QT. Making use of an effective energy functional appropriate for the adiabatic approximation [5], we prove J z ∈ [−1, 1] with the actual value determined by the angle between the z-axis and the direction of the B-field. We then generalize to the spin-F case. Finally, our result is extended to an IPT.The Hamiltonian of a spin-1 atomic condensate with N atoms in a magnetic trap is H = H S + H I with the single atom partand the atom-atom interaction HamiltonianT denotes the annih...

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Optically plugged quadrupole trap for Bose-Einstein condensates

Cited by 39 publications

References 21 publications

Versatile transporter apparatus for experiments with optically trapped Bose–Einstein condensates

Versatile transporter apparatus for experiments with optically trapped Bose–Einstein condensates

Production of Rubidium Bose—Einstein Condensate in an Optically Plugged Magnetic Quadrupole Trap

Angular Momentum of a Magnetically Trapped Atomic Condensate

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