We have prepared and detected quantum coherences with long dephasing times at the level of single trapped cesium atoms. Controlled transport by an "optical conveyor belt" over macroscopic distances preserves the atomic coherence with slight reduction of coherence time. The limiting dephasing effects are experimentally identified and are of technical rather than fundamental nature. We present an analytical model of the reversible and irreversible dephasing mechanisms. Coherent quantum bit operations along with quantum state transport open the route towards a "quantum shift register" of individual neutral atoms.
Using optical dipole forces we have realized controlled transport of a single or any desired small number of neutral atoms over a distance of a centimeter with sub-micrometer precision. A standing wave dipole trap is loaded with a prescribed number of cesium atoms from a magneto-optical trap. Mutual detuning of the counter-propagating laser beams moves the interference pattern, allowing us to accelerate and stop the atoms at preselected points along the standing wave. The transportation efficiency is close to 100%. This optical "single-atom conveyor belt" represents a versatile tool for future…
Fast and nearly lossless atomic transport, enabled by moving the confining trap, is a prerequisite for many quantum-technology applications. While theoretical studies of this problem have heretofore focussed almost exclusively on simplified scenarios (one-dimensional systems, purely harmonic confining potentials, etc.), we investigate it here in the experimentally relevant setting of a moving optical lattice ({\em optical conveyor belt}). We model single-atom transport in this system by taking fully into account its three-dimensional, anharmonic confining potential. We do so using the establis…
Here we report of a design and the performance of an optimized micro-fabricated conveyor belt for precise and adiabatic transportation of cold atoms. A theoretical model is presented to determine optimal currents in conductors used for the transportation. We experimentally demonstrate a fast adiabatic transportation of Rubidium ($^{87}$Rb) cold atoms with minimal loss and heating with as few as three conveyor belt conductors. This novel design of a multilayered conveyor belt structure is fabricated in aluminium nitride ($AlN$) because of its outstanding thermal and electrical properties. This …
The problem of high-speed transport for cold atoms with minimal heating has received considerable attention in theory and experiment. Much theoretical work has focused on solutions of general problems, often assuming a harmonic trapping potential or a 1D geometry. However in the case of optical conveyor belts these assumptions are not always valid. Here we present experimental and numerical studies of the effects of various motional parameters on heating and retention of atoms transported in an optical conveyor. Our numerical model is specialized to the geometry of a moving optical lattice and…
A protocol for synchronizing distant clocks is proposed that does not rely on the arrival times of the signals which are exchanged, and an optical implementation based on coherent-state pulses is described. This protocol is not limited by any dispersion that may be present in the propagation medium through which the light signals are exchanged. Possible improvements deriving from the use of quantum-mechanical effects are also addressed.
We report the realization of a robust magnetic transport scheme to bring 3x10^8 ultracold 87Rb atoms into a cryostat. The sequence starts with standard laser cooling and trapping of 87Rb atoms, transporting first horizontally and then vertically through the radiation shields into a cryostat by a series of normal- and superconducting magnetic coils. Loading the atoms in a superconducting microtrap paves the way for studying the interaction of ultracold atoms with superconducting surfaces and quantum devices requiring cryogenic temperatures.
We demonstrate optical transport of cold cesium atoms over millimeter-scale distances along an optical nanofiber. The atoms are trapped in a one-dimensional optical lattice formed by a two-color evanescent field surrounding the nanofiber, far red- and blue-detuned with respect to the atomic transition. The blue-detuned field is a propagating nanofiber-guided mode while the red-detuned field is a standing-wave mode which leads to the periodic axial confinement of the atoms. Here, this standing wave is used for transporting the atoms along the nanofiber by mutually detuning the two counter-propa…
Impact of the local valley splitting on the coherence of conveyor-belt spin shuttling in $^{28}$Si/SiGe
JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University（亚琛研究联合会量子信息研究所、于利希研究中心有限公司和亚琛工业大学）；Helmholtz Nano Facility (HNF), Forschungszentrum Jülich（亥姆霍兹纳米设施（HNF）、于利希研究中心）；QuTech and Kavli Institute of Nanoscience, Delft University of Technology（夸特赫与卡弗里纳米科学研究所、代尔夫特理工大学）；Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）
We present a toolbox for cold atom manipulation with time-dependent magnetic fields generated by an atom chip. Wire layouts, detailed experimental procedures and results are presented for the following experiments: Use of a magnetic conveyor belt for positioning of cold atoms and Bose-Einstein condensates with a resolution of two nanometers; splitting of thermal clouds and BECs in adjustable magnetic double well potentials; controlled splitting of a cold reservoir. The devices that enable these manipulations can be combined with each other. We demonstrate this by combining reservoir splitter a…
Mapping g-factors and complex intervalley coupling in Si/SiGe by conveyor-mode shuttling
JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University（JARA-FIT量子信息研究所，于利希研究中心有限公司和亚琛工业大学）；Helmholtz Nano Facility (HNF), Forschungszentrum Jülich（亥姆霍兹纳米设施（HNF），于利希研究中心）；QuTech and Kavli Institute of Nanoscience, Delft University of Technology（奎特克与卡弗里纳米科学研究所，代尔夫特理工大学）；Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）
Hybrid quantum systems have the potential of mitigating current challenges in developing a scalable quantum computer. Of particular interest is the hybridization between atomic and superconducting qubits. We demonstrate a novel experimental setup for transferring and trapping ultracold atoms inside a millikelvin cryogenic environment, where interactions between atomic and superconducting qubits can be established, paving the way for hybrid quantum systems. $^{87}\text{Rb}$ atoms are prepared in a conventional magneto-optical trap and transported via a magnetic conveyor belt into a UHV compatib…
Trapped atoms near nanophotonics form an exciting platform for bottom-up synthesis of strongly interacting quantum matter. The ability to induce tunable long-range atom-atom interactions with photons presents an opportunity to explore many-body physics and quantum optics. Here we implement a configurable optical tweezer array over a planar photonic circuit tailored for cold atom integration and control for trapping and high-fidelity imaging of one or more atoms in an array directly on a photonic structure. Using an optical conveyor belt formed by a moving optical lattice within a tweezer poten…
We analyze the coupling of atoms or atom-like emitters to nanophotonic waveguides in the presence of propagating acoustic waves. Specifically, we show that strong index modulations induced by such waves can drastically modify the effective photonic density of states and thereby influence the strength, the directionality, as well as the overall characteristics of photon emission and absorption processes. These effects enable a complete dynamical control of light-matter interactions in waveguide structures, which even in a two dimensional system can be used to efficiently exchange individual pho…
We demonstrate continuous loading of strontium atoms into a high finesse ring cavity and observe continuous strong collective coupling in the form of a vacuum Rabi splitting between the atoms and the cavity on the 7.5 kHz transition $^1{\rm S}_0$ to $^3{\rm P}_1$. The atoms are loaded into the cavity from a 3D narrow linewidth molasses, thus avoiding large magnetic field gradients and associated broadening of transition frequencies. The ring cavity allows us to realize a deterministic conveyor belt to transport atoms away from the loading region where the laser cooling beams lead to broadening…
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 pa…
