0000000001075113
AUTHOR
Patrick Windpassinger
Rydberg excitation of cold atoms inside a hollow core fiber
We report on a versatile, highly controllable hybrid cold Rydberg atom fiber interface, based on laser cooled atoms transported into a hollow core Kagom\'{e} crystal fiber. Our experiments are the first to demonstrate the feasibility of exciting cold Rydberg atoms inside a hollow core fiber and we study the influence of the fiber on Rydberg electromagnetically induced transparency (EIT) signals. Using a temporally resolved detection method to distinguish between excitation and loss, we observe two different regimes of the Rydberg excitations: one EIT regime and one regime dominated by atom loss. These results are a substantial advancement towards future use of our system for quantum simulat…
Laser spectroscopy of the 1001nm ground state transition in dysprosium
We present a direct excitation of the presumably ultranarrow $1001\ensuremath{-}\mathrm{nm}$ ground-state transition in atomic dysprosium. By using resonance ionization spectroscopy with pulsed Ti:sapphire lasers at a hot cavity laser ion source, we were able to measure the isotopic shifts in the $1001\ensuremath{-}\mathrm{nm}$ line between all seven stable isotopes. Furthermore, we determined the upper level energy from the atomic transition frequency of the $^{164}\mathrm{Dy}$ isotope as $9991.004(1)\phantom{\rule{0.16em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ and confirm the level energy listed in the NIST database. Since a sufficiently narrow natural linewidth is an essential prerequisit…
Autonomous frequency stabilization of two extended cavity diode lasers at the potassium wavelength on a sounding rocket
We have developed, assembled, and flight-proven a stable, compact, and autonomous extended cavity diode laser (ECDL) system designed for atomic physics experiments in space. To that end, two micro-integrated ECDLs at 766.7 nm were frequency stabilized during a sounding rocket flight by means of frequency modulation spectroscopy (FMS) of 39^K and offset locking techniques based on the beat note of the two ECDLs. The frequency stabilization as well as additional hard- and software to test hot redundancy mechanisms were implemented as part of a state-machine, which controlled the experiment completely autonomously throughout the entire flight mission.
Space-borne Bose–Einstein condensation for precision interferometry
Space offers virtually unlimited free-fall in gravity. Bose-Einstein condensation (BEC) enables ineffable low kinetic energies corresponding to pico- or even femtokelvins. The combination of both features makes atom interferometers with unprecedented sensitivity for inertial forces possible and opens a new era for quantum gas experiments. On January 23, 2017, we created Bose-Einstein condensates in space on the sounding rocket mission MAIUS-1 and conducted 110 experiments central to matter-wave interferometry. In particular, we have explored laser cooling and trapping in the presence of large accelerations as experienced during launch, and have studied the evolution, manipulation and interf…
Feynmans Idee wird Realität
Quantensimulatoren sind Quantencomputer fur spezielle Fragestellungen. An der Berechnung hochkorrelierter Vielteilchensysteme zum Beispiel scheitern konventionelle Computer. Quantensimulatoren stellen solche komplexen Quantensysteme, zum Beispiel aus der Festkorperphysik, mit einem sehr gut kontrollierbaren Modellsystem nach. Mit ultrakalten Gasen in optischen Fallen als Modellsysteme wurden in den vergangenen Jahren faszinierende Ergebnisse erzielt. Drei vorgestellte Beispiele zeigen dies. Das erste Beispiel ist der Ubergang von einem delokalisierten Suprafluid in einen Mott-Isolator aus fest lokalisierten Teilchen. Das zweite Beispiel sind frustrierte Spinsysteme, zum Beispiel auf Dreieck…
Double Bragg Interferometry.
We employ light-induced double Bragg diffraction of delta-kick collimated Bose-Einstein condensates to create three symmetric Mach-Zehnder interferometers. They rely on (i) first-order, (ii) two successive first-order, and (iii) second-order processes which demonstrate the scalability of the corresponding momentum transfer. With respect to devices based on conventional Bragg scattering, these symmetric interferometers double the scale factor and feature a better suppression of noise and systematic uncertainties intrinsic to the diffraction process. Moreover, we utilize these interferometers as tiltmeters for monitoring their inclination with respect to gravity.
Optical frequency combs for space applications
Optical frequency comb-based high resolution laser spectroscopy has been demonstrated in space under micro-gravity on two sounding rocket based experiments. The comb has been used to simultaneously measure two different atomic transitions.
Design of a compact diode laser system for dual-species atom interferometry with rubidium and potassium in space
We report on a micro-integrated high power diode laser based system for the MAIUS II/III missions. The laser system features fiber coupled and frequency stabilized external cavity diode lasers (ECDL) for laser cooling, Bose-Einstein condensate (BEC) generation and dual species atom interferometry with rubidium and potassium on board a sounding rocket.
Highly stable Zerodur based optical benches for microgravity applications and other adverse environments
A number of cold atom experiments are restrained by the impeding effects of gravity. While efforts have been made to overcome these limitations in a gravitational environment, another approach is placing the experiment in a microgravity environment, as can be found aboard sounding rockets, satellites or a space station. The cornerstone of such experiments is a robust laser system. The adverse conditions during a rocket launch impose stringent requirements on thermal stability and resilience against mechanical stress on this part of the experimental setup. Furthermore, the very limited space found on any of the aforementioned microgravity platforms necessitates maximal miniaturization. In or…
Engineering novel optical lattices.
Optical lattices have developed into a widely used and highly recognized tool to study many-body quantum physics with special relevance for solid state type systems. One of the most prominent reasons for this success is the high degree of tunability in the experimental setups. While at the beginning quasi-static, cubic geometries were mainly explored, the focus of the field has now shifted toward new lattice topologies and the dynamical control of lattice structures. In this review we intend to give an overview of the progress recently achieved in this field on the experimental side. In addition, we discuss theoretical proposals exploiting specifically these novel lattice geometries.
Towards nonlinear optics with cold Rydberg atoms inside a hollow core fiber
We present an experimental setup for studying strongly nonlinear light-matter interactions using cold atoms inside a hollow core fiber. A Rydberg EIT process can potentially be used to generate strong and tunable effective photon-photon interactions.
Note: Simultaneous modulation transfer spectroscopy on transitions of multiple atomic species for compact laser frequency reference modules
We present a technique for simultaneous laser frequency stabilization on transitions of multiple atomic species with a single optical setup. The method is based on modulation transfer spectroscopy, and the signals are separated by modulating at different frequencies and electronically filtered. As a proof of concept, we demonstrate simultaneous spectroscopy of the potassium D1, D2 and rubidium D2 transitions. The technique can be extended in principle to other atomic species given the availability of optics and cells and allows the development of versatile and compact frequency reference modules.
Controlled transport of stored light
Controlled manipulation, storage, and retrieval of quantum information is essential for quantum communication and computing. Quantum memories for light, realized with cold atomic samples as the storage medium, are prominent for their high storage efficiencies and lifetime. We demonstrate the controlled transport of stored light over 1.2 mm in such a storage system and show that the transport process and its dynamics only have a minor effect on the coherence of the storage. Extending the presented concept to longer transport distances and augmenting the number of storage sections will allow for the development of novel quantum devices such as optical racetrack memories or optical quantum reg…
Space-borne frequency comb metrology
Precision time references in space are of major importance to satellite-based fundamental science, global satellite navigation, earth observation, and satellite formation flying. Here we report on the operation of a compact, rugged, and automated optical frequency comb setup on a sounding rocket in space under microgravity. The experiment compared two clocks, one based on the optical D2 transition in Rb, and another on hyperfine splitting in Cs. This represents the first frequency comb based optical clock operation in space, which is an important milestone for future satellite-based precision metrology. Based on the approach demonstrated here, future space-based precision metrology can be i…
Determining the deformation and resulting coupling efficiency degradation of ultrastable fiber-coupled optical benches under load.
Fiber-coupled optical benches are an integral part of many laser systems. The base of such an optical bench is usually a slab of solid material, onto which optical components are fixed. In many environments, the ability to retain high fiber coupling efficiency under mechanical loads is essential. In this article, we study the fiber-to-fiber coupling efficiency under the application of static mechanical loads experimentally and theoretically: We constructed a simple three-point bending setup to interferometrically measure the deformation of an optical bench under load. Using the same setup, we further recorded the resulting coupling efficiency variations. The examined optical benches are bas…
Micro lensing induced lineshapes in a single mode cold-atom hollow-core fiber interface
We report on the observation of strong transmission line shape alterations in a cold-atom-hollow-core-fiber interface. We show that this can lead to a significant overestimation of the assigned resonant optical depth for high atom densities. By modeling light beam propagation in an inhomogeneous dispersive medium, we attribute the observations to micro lensing in the atomic ensemble in combination with the mode selection of the atom-fiber interface. The approach is confirmed by studies of Rydberg electromagnetically induced transparency line shapes.
Spectroscopy of the 1001-nm transition in atomic dysprosium
We report on spectroscopy of cold dysprosium atoms on the $1001\text{\ensuremath{-}}\mathrm{nm}$ transition and present measurements of the excited-state lifetime which is at least $87(7)\phantom{\rule{4pt}{0ex}}\mathrm{ms}$ long. Due to the long excited-state lifetime we are able to measure the ratio of the excited-state polarizability to the ground-state polarizability at $1064\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ to be 0.83(0.13) by parametric heating in an optical dipole trap. In addition we measure the isotope shifts of the three most abundant bosonic isotopes of dysprosium on the $1001\text{\ensuremath{-}}\mathrm{nm}$ transition with an accuracy better than $30\phantom{\rule{4pt}{0ex}…
Highly angular resolving beam separator based on total internal reflection
We present an optical element for the separation of superimposed beams that only differ in angle. The beams are angularly resolved and separated by total internal reflection at an air gap between two prisms. As a showcase application, we demonstrate the separation of superimposed beams of different diffraction orders directly behind acousto-optic modulators for an operating wavelength of 800 nm. The wavelength as well as the component size can easily be adapted to meet the requirements of a wide variety of applications. The presented optical element allows one to reduce the lengths of beam paths and thus to decrease laser system size and complexity.
Engineering Ising-XY spin models in a triangular lattice via tunable artificial gauge fields,
Emulation of gauge fields for ultracold atoms provides access to a class of exotic states arising in strong magnetic fields. Here we report on the experimental realisation of tunable staggered gauge fields in a periodically driven triangular lattice. For maximal staggered magnetic fluxes, the doubly degenerate superfluid ground state breaks both a discrete Z2 (Ising) symmetry and a continuous U(1) symmetry. By measuring an Ising order parameter, we observe a thermally driven phase transition from an ordered antiferromagnetic to an unordered paramagnetic state and textbook-like magnetisation curves. Both the experimental and theoretical analysis of the coherence properties of the ultracold g…
ZERODUR based optical systems for quantum gas experiments in space
Abstract Numerous quantum technologies make use of a microgravity environment e.g. in space. Operating in this extreme environment makes high demands on the experiment and especially the laser system regarding miniaturization and power consumption as well as mechanical and thermal stability. In our systems, optical modules consisting of ZERODUR® based optical benches with free-space optics are combined with fiber components. Suitability of the technology has been demonstrated in the successful sounding rocket missions FOKUS, KALEXUS and MAIUS-1. Here, we report on our toolkit for stable optical benches including mounts, fixed and adjustable mirrors as well as polarization maintaining fiber …
Simultaneous modulation transfer spectroscopy on transitions of multiple atomic species for compact laser frequency reference modules
We present a technique for simultaneous laser frequency stabilization on transitions of multiple atomic species with a single optical setup. The method is based on modulation transfer spectroscopy and the signals are separated by modulating at different frequencies and electronically filtered. As a proof of concept, we demonstrate simultaneous spectroscopy of the potassium D$_1$, D$_2$ and rubidium D$_2$ transitions. The technique can easily be extended to other atomic species and allows the development of versatile and compact frequency reference modules.
Collective-Mode Enhanced Matter-Wave Optics
International audience; In contrast to light, matter-wave optics of quantum gases deals with interactions even in free space and for ensembles comprising millions of atoms. We exploit these interactions in a quantum degenerate gas as an adjustable lens for coherent atom optics. By combining an interaction-driven quadrupole-mode excitation of a Bose-Einstein condensate (BEC) with a magnetic lens, we form a time-domain matter-wave lens system. The focus is tuned by the strength of the lensing potential and the oscillatory phase of the quadrupole mode. By placing the focus at infinity, we lower the total internal kinetic energy of a BEC comprising 101(37) thousand atoms in three dimensions to …
Highly controlled optical transport of cold atoms into a hollow-core fiber
We report on an efficient and highly controlled cold atom hollow-core fiber interface, suitable for quantum simulation, information, and sensing. The main focus of this manuscript is a detailed study on transporting cold atoms into the fiber using an optical conveyor belt. We discuss how we can precisely control the spatial, thermal, and temporal distribution of the atoms by, e.g., varying the speed at which the atoms are transported or adjusting the depth of the transport potential according to the atomic position. We characterize the transport of atoms to the fiber tip for these different parameters. In particular, we show that by adapting the transport potential we can lower the temperat…
Sawtooth-wave adiabatic-passage slowing of dysprosium
We report on sawtooth wave adiabatic passage (SWAP) slowing of bosonic and fermionic dysprosium isotopes by using a 136 kHz wide transition at 626 nm. A beam of precooled atoms is further decelerated in one dimension by the SWAP force and the amount of atoms at near zero velocity is measured. We demonstrate that the SWAP slowing can be twice as fast as in a conventional optical molasses operated on the same transition. In addition, we investigate the parameter range for which the SWAP force is efficiently usable in our set-up, and relate the results to the adiabaticity condition. Furthermore, we add losses to the hyperfine ground-state population of fermionic dysprosium during deceleration …