About
50
Publications
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Introduction
Additional affiliations
April 1996 - March 2001
FOM Institute for Atomic and Molecular Physics, AMOLF
Position
- PhD Student
October 1990 - February 1996
August 2009 - present
Education
March 1996 - February 2001
University of Amsterdam, Institute for Atomic and Molecular Physics (AMOLF)
Field of study
- Thesis: Bose-Einstein Condensation with High Atom Number in a Deep Magnetic Trap
October 1990 - February 1996
University of Konstanz, Germany
Field of study
- Physics
Publications
Publications (50)
We report the creation of ultracold ground state Li6K40 polar molecules with high efficiency. Starting from weakly bound molecules, stimulated Raman adiabatic passage is adopted to coherently transfer the molecules to their singlet rovibrational ground state |XΣ+1,v=0,J=0⟩. By employing a singlet stimulated Raman adiabatic passage pathway and low-p...
We report the creation of ultracold ground state 6 Li 40 K polar molecules with high efficiency. Starting from weakly-bound molecules state, stimulated Raman adiabatic passage (STIRAP) is adopted to coherently transfer the molecules to their singlet ro-vibrational ground state X 1 Σ + , v = 0, J = 0. By employing a singlet STIRAP pathway and low-ph...
We present the comparison of a field-programmable-gate-array (FPGA) based digital servo module with an analog counterpart for the purpose of laser frequency stabilization to a high-finesse optical cavity. The transfer functions of both the digital and analog modules for proportional–integral–derivative control are measured. For the lasers stabilize...
We report on a high-resolution spectroscopic survey of 6Li40K molecules near the 2S + 4P dissociation threshold and produce a fully empirical representation for the B1Π potential by connecting available short- and long-range data. The purpose is to identify a suitable intermediate state for a coherent Raman transfer to the absolute ground state, an...
We investigate the phase noise properties of our Raman laser system for its application in the coherent ground state transfer of LiK polar molecules and discuss recent improvements.
We report on a high-resolution spectroscopic survey of ${}^{6}\textrm{Li}{}^{40}\textrm{K}$ molecules near the $2\textrm{S}+4\textrm{P}$ dissociation threshold and produce a fully empirical representation for the $\textrm{B}^{1}\Pi$ potential by connecting available short- and long-range data. The purpose is to identify a suitable intermediate stat...
Starting from weakly bound Feshbach molecules, we demonstrate a two-photon pathway to the dipolar ground state of bi-alkali molecules that involves only singlet-to-singlet optical transitions. This pathway eliminates the search for a suitable intermediate state with sufficient singlet-triplet mixing and the exploration of its hyperfine structure, a...
Starting from weakly bound Feshbach molecules, we demonstrate a two-photon pathway to the dipolar ground state of bi-alkali molecules that involves only singlet-to-singlet optical transitions. This pathway eliminates the search for a suitable intermediate state with sufficient singlet-triplet mixing and the exploration of its hyperfine structure, a...
We present an efficient scheme to implement a gray optical molasses for sub-Doppler cooling of Li6 atoms with minimum experimental overhead. To integrate the D1 light for the gray molasses cooling into the same optical setup that is used for the D2 light for a standard magneto-optical trap (MOT), we rapidly switch the injection seeding of a slave l...
We report on a transfer-lock laser frequency stabilization that utilizes a frequency comb (FC) and a radio frequency counter referenced to a GPS frequency standard to compensate for the frequency drifts of two lasers, which are locked to a single passive Fabry–Perot resonator (FPR). The method requires only one optical phase lock with the FC and al...
ICOLS features the latest developments in the area of laser spectroscopy and related topics in atomic, molecular, and optical physics and other disciplines. The talks covered a broad range of exciting physics, such as precision tests of fundamental symmetries with atoms and molecules, atomic clocks, quantum many-body physics with ultra-cold atoms,...
This roadmap bundles fast developing topics in experimental optical quantum sciences, addressing current challenges as well as potential advances in future research. We have focused on three main areas: quantum assisted high precision measurements, quantum information/simulation, and quantum gases. Quantum assisted high precision measurements are d...
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 to...
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 to...
We report an experimental study of peak and phase-space density of a
two-stage magneto-optical trap (MOT) of 6-Li atoms, which exploits the narrower
$2S_{1/2}\rightarrow 3P_{3/2}$ ultra-violet (UV) transition at 323 nm following
trapping and cooling on the more common D2 transition at 671 nm. The UV MOT is
loaded from a red MOT and is compressed to...
We report on a calibration procedure that enhances the precision of an interferometer based frequency stabilization by several orders of magnitude. For this purpose, the frequency deviations of the stabilization are measured precisely by means of a frequency comb. This allows us to implement several calibration steps that compensate different syste...
We present a systematic investigation of attractive binary mixtures in the presence of both spin- and mass-imbalance in one-dimensional setups described by the Hubbard model. After discussing typical cold atomic experimental realizations and the relation between microscopic and effective parameters, we study several many-body features of trapped Fe...
In a Mott insulator, repulsive interactions suppress conductivity. Such behaviour has been demonstrated, individually, for both bosonic and fermionic atoms in optical lattices. Now, a Bose-Fermi mixture is found to be Mott insulating too, even when the individual components are not.
DOI:https://doi.org/10.1103/PhysRevLett.105.269904
We investigate s-wave interactions in a two-species Fermi-Fermi mixture of 6Li and 40K. We develop for this case the method of cross-dimensional relaxation and find from a kinetic model, Monte Carlo simulations, and measurements that the individual relaxation rates differ due to the mass difference. The method is applied to measure the elastic cros...
We investigate s-wave interactions in a two-species Fermi-Fermi mixture of (6)Li and (40)K. We develop for this case the method of cross-dimensional relaxation and find from a kinetic model, Monte Carlo simulations, and measurements that the individual relaxation rates differ due to the mass difference. The method is applied to measure the elastic...
Spin mixtures of quantum-degenerate fermionic gases exhibit long
lifetimes in the strongly-interacting regime near a Feshbach resonance.
This has opened the door for numerous key experiments like the creation
of Fermi-Fermi molecules, the realization of molecular BEC, the
observation of a pairing gap and of superfluidity in a fermionic gas in
the B...
We report on the first creation of ultracold bosonic heteronuclear molecules of two fermionic species, $^{6}\mathrm{Li}$ and $^{40}\mathrm{K}$, by a magnetic field sweep across an interspecies $s$-wave Feshbach resonance. This allows us to associate up to $4\ifmmode\times\else\texttimes\fi{}{10}^{4}$ molecules with high efficiencies of up to 50%. U...
We report on the first creation of ultracold bosonic heteronuclear molecules of two fermionic species, 6Li and 40K, by a magnetic field sweep across an interspecies s-wave Feshbach resonance. This allows us to associate up to 4x10^4 molecules with high efficiencies of up to 50%. Using direct imaging of the molecules, we measure increased lifetimes...
We report on the generation of a quantum degenerate Fermi-Fermi mixture of two different atomic species. The quantum degenerate mixture is realized employing sympathetic cooling of fermionic 6Li and 40K gases by an evaporatively cooled bosonic 87Rb gas. We describe the combination of trapping and cooling methods that proved crucial to successfully...
We report on the generation of a quantum degenerate Fermi-Fermi mixture of two different atomic species. The quantum degenerate mixture is realized employing sympathetic cooling of fermionic Li-6 and K-40 gases by an evaporatively cooled bosonic Rb-87 gas. We describe the combination of trapping and cooling methods that proved crucial to successful...
We report on the simultaneous trapping of two fermionic species, Li6
and K40 , and a bosonic species, Rb87 , demonstrating the first
three-species magneto-optical trap (“triple MOT”). The
apparatus including the atom sources and the three laser systems is
described, and the single-species MOTs and the triple MOT are
characterized. In triple MOT ope...
Phase Coherence Length of an Elongated Bose-Einstein CondensateFocusing of Bose-Einstein Condensates in Free FlightBose-Einstein Condensation in a MicrotrapRole of Molecular Dissociation in Feshbach-Interacting 85Rb CondensatesMicroscopic Theory of Oscillations between Atoms and Molecules in a Bose-Einstein CondensateDecay of an Ultracold Fermionic...
We have produced a quantum degenerate 6Li Fermi gas with up to 7 x 10(7) atoms, an improvement by a factor of 50 over all previous experiments with degenerate Fermi gases. This was achieved by sympathetic cooling with bosonic 23Na in the F=2, upper hyperfine ground state. We have also achieved Bose-Einstein condensation of F=2 sodium atoms by direc...
Radio-frequency techniques were used to study ultracold fermions. We observed the absence of mean-field "clock" shifts, the dominant source of systematic error in current atomic clocks based on bosonic atoms. This is a direct consequence of fermionic antisymmetry. Resonance shifts proportional to interaction strengths were observed in a three-level...
Radio-frequency techniques were used to study ultracold fermions. We observed the absence of mean-field "clock" shifts, the dominant source of systematic error in current atomic clocks based on bosonic atoms. This absence is a direct consequence of fermionic antisymmetry. Resonance shifts proportional to interaction strengths were observed in a thr...
We have produced a quantum system in which a large ^6Li Fermi sea coexists with a ^23Na BEC. In earlier studies [1], we achieved simultaneous degeneracy by sympathetically cooling ^6Li with ^23Na in the lower hyperfine state (F=1). By changing to the upper hyperfine state (F=2), we have overcome earlier problems from interspecies spin-exchange coll...
We report on studies of a degenerate, interacting mixture of fermions. We prepare ^6Li fermions by sympathetic cooling with ^23Na bosons in a magnetic trap [1]. We then transfer the fermions into an optical trap and manipulate both the spin composition and the external magnetic field to bring the system into the vicinity of a Feshbach resonance [2]...
We report the formation of Bose-Einstein condensates into nonequilibrium states. Our condensates are much longer than equilibrium condensates with the same number of atoms, show strong phase fluctuations, and have a dynamical evolution similar to that of quadrupole shape oscillations of regular condensates. The condensates emerge in elongated traps...
We studied the magnetic field dependence of the inelastic decay of an ultracold, optically trapped fermionic 6Li gas of different spin compositions. The spin mixture of the two lowest hyperfine states showed two decay resonances at 550 and 680 G, consistent with the predicted Feshbach resonances for elastic s-wave collisions. The observed lifetimes...
The kinetic energy of an atom recoiling due to absorption of a photon was measured as a frequency, using an interferometric technique called "contrast interferometry." Optical standing wave pulses were used to create a symmetric three-path interferometer with a Bose-Einstein condensate. Its recoil phase, measurable with a single shot, varies quadra...
We studied the magnetic field dependence of the inelastic decay of an ultracold, optically trapped 6-Li gas of different spin compositions. The spin mixture of the two lowest hyperfine states showed two decay resonances at 550 G and 680 G due to two-body collisions, close to the predicted Feshbach resonance of the elastic s-wave collisions at 800 G...
We have produced a macroscopic quantum system in which a 6Li Fermi sea coexists with a large and stable 23Na Bose-Einstein condensate. This was accomplished using interspecies sympathetic cooling of fermionic 6Li in a thermal bath of bosonic 23Na. The system features rapid thermalization and long lifetimes.
One route to a high precision measurement of the fine-structure constant involves a precise determination of the ratio hbar / m_alkali [1]. This ratio can be determined from a measurement of the recoil energy due to photon absorption in an atom-light interferometer. We recently demonstrated a new type of interferometer to do this using Bragg scatte...
We have produced a macroscopic quantum system in which a Li-6 Fermi sea coexists with a large and stable Na-23 Bose-Einstein condensate. This was accomplished using inter-species sympathetic cooling of fermionic Li-6 in a thermal bath of bosonic Na-23.
We experimentally slly the u s of two-dimensTODZ magneto-optical trapping (2DMOT) for the generation of sj w beams of coldatoms out of a vapor cell. A particularly high flux of 9
We report on master-oscillator power amplification using a broad-area laser diode (BAL) emitting at a wavelength of λ =780nm.
The master oscillator is an injection-locked single-mode diode laser delivering a seeding beam of 35mW, which is amplified
in double pass through the BAL up to 410mW. After beam shaping and spatial filtering by a single-mode...
We experimentally study the use of two-dimensional magneto-optical trapping (2D-MOT) for the generation of slow beams of cold atoms out of a vapor cell. A particularly high flux of 9×109 rubidium atoms/s at a mean velocity of 8 m/s is obtained using a combination of magneto-optical trapping in two dimensions and Doppler cooling in the third dimensi...
We report on atom optical experiments employing a magnetooptical trap as a source of a pulsed beam of slow atoms. After turning off the trap, experiments are performed on the cloud of atoms in free fall over a distance of 45 cm. We give a detailed description of the apparatus and discuss experimental results on the diffraction of atoms from a stand...
We report on an experiment with polarized atoms passing a standing light wave, where the atom's position is encoded (entangled) with the excitation amplitude of two long lived electronic states. Position information can be obtained a posteriori by measuring the electronic state. If this measurement is performed, the atom is localized in an array of...