98 research outputs found
Quantum Test of the Universality of Free Fall
We simultaneously measure the gravitationally-induced phase shift in two
Raman-type matter-wave interferometers operated with laser-cooled ensembles of
Rb and K atoms. Our measurement yields an E\"otv\"os ratio of
. We briefly estimate possible
bias effects and present strategies for future improvements
Testing the universality of free fall with rubidium and ytterbium in a very large baseline atom interferometer
We propose a very long baseline atom interferometer test of Einstein's
equivalence principle (EEP) with ytterbium and rubidium extending over 10m of
free fall. In view of existing parametrizations of EEP violations, this choice
of test masses significantly broadens the scope of atom interferometric EEP
tests with respect to other performed or proposed tests by comparing two
elements with high atomic numbers. In a first step, our experimental scheme
will allow reaching an accuracy in the E\"otv\"os ratio of .
This achievement will constrain violation scenarios beyond our present
knowledge and will represent an important milestone for exploring a variety of
schemes for further improvements of the tests as outlined in the paper. We will
discuss the technical realisation in the new infrastructure of the Hanover
Institute of Technology (HITec) and give a short overview of the requirements
to reach this accuracy. The experiment will demonstrate a variety of techniques
which will be employed in future tests of EEP, high accuracy gravimetry and
gravity-gradiometry. It includes operation of a force sensitive atom
interferometer with an alkaline earth like element in free fall, beam splitting
over macroscopic distances and novel source concepts
Spontaneous symmetry breaking in spinor Bose-Einstein condensates
We present an analytical model for the theoretical analysis of spin dynamics
and spontaneous symmetry breaking in a spinor Bose-Einstein condensate (BEC).
This allows for an excellent intuitive understanding of the processes and
provides good quantitative agreement with experimental results in Phys. Rev.
Lett. 105, 135302 (2010). It is shown that the dynamics of a spinor BEC
initially prepared in an unstable Zeeman state mF=0 (|0>) can be understood by
approximating the effective trapping potential for the state |+-1> with a
cylindrical box potential. The resonances in the creation efficiency of these
atom pairs can be traced back to excitation modes of this confinement. The
understanding of these excitation modes allows for a detailed characterization
of the symmetry breaking mechanism, showing how a twofold spontaneous breaking
of spatial and spin symmetry can occur. In addition a detailed account of the
experimental methods for the preparation and analysis of spinor quantum gases
is given.Comment: 12 pages, 14 figure
QUANOMET : Eine Forschungslinie der strategischen Allianz Braunschweig - Hannover
Die Quanten- und Nanometrologie (QUANOMET) verfolgt die methodische Weiterentwicklung und Innovation immer präziserer und empfindlicherer Messverfahren und ist eine von drei Forschungslinien eines Wissenschaftsbündnisses zwischen der Leibniz Universität Hannover und der Technischen Universität Braunschweig. Wissenschaftler beider Hochschulen berichten, wie das Projekt entstanden ist und welche Ziele es hat
Self-alignment of a compact large-area atomic Sagnac interferometer
We report on the realization of a compact atomic Mach-Zehndertype Sagnac interferometer of 13.7 cm length, which covers an area of 19 mm(2) previously reported only for large thermal beam interferometers. According to Sagnac's formula, which holds for both light and atoms, the sensitivity for rotation rates increases linearly with the area enclosed by the interferometer. The use of cold atoms instead of thermal atoms enables miniaturization of Sagnac interferometers without sacrificing large areas. In comparison with thermal beams, slow atoms offer better matching of the initial beam velocity and the velocity with which the matter waves separate. In our case, the area is spanned by a cold atomic beam of 2.79m s(-1), which is split, deflected and combined by driving a Raman transition between the two hyperfine ground states of Rb-87 in three spatially separated light zones. The use of cold atoms requires a precise angular alignment and high wave front quality of the three independent light zones over the cloud envelope. We present a procedure for mutually aligning the beam splitters at the microradian level by making use of the atom interferometer itself in different configurations. With this method, we currently achieve a sensitivity of 6.1 x 10(-7) rad s(-1) Hz(-1/2).DFG/SFB/407EU/NESTEU/FINAQSEU/EuroquasarEU/IQSQUESTMax-Planck-GesellschaftINTERCAN networkUFA-DF
Interference of Clocks: A Quantum Twin Paradox
The phase of matter waves depends on proper time and is therefore susceptible
to special-relativistic (kinematic) and gravitational time dilation (redshift).
Hence, it is conceivable that atom interferometers measure general-relativistic
time-dilation effects. In contrast to this intuition, we show that light-pulse
interferometers without internal transitions are not sensitive to gravitational
time dilation, whereas they can constitute a quantum version of the
special-relativistic twin paradox. We propose an interferometer geometry
isolating the effect that can be used for quantum-clock interferometry.Comment: 9 Pages, 2 Figure
Rapid generation and number-resolved detection of spinor Rubidium Bose-Einstein condensates
High data acquisition rates and low-noise detection of ultracold neutral
atoms present important challenges for the state tomography and interferometric
application of entangled quantum states in Bose-Einstein condensates. In this
article, we present a high-flux source of Rb Bose-Einstein condensates
combined with a number-resolving detection. We create Bose-Einstein condensates
of atoms with no discernible thermal fraction within s
using a hybrid evaporation approach in a magnetic/optical trap. For the
high-fidelity tomography of many-body quantum states in the spin degree of
freedom [arXiv:2207.01270], it is desirable to select a single mode for a
number-resolving detection. We demonstrate the low-noise selection of
subsamples of up to atoms and their subsequent detection with a counting
noise below atoms. The presented techniques offer an exciting path
towards the creation and analysis of mesoscopic quantum states with
unprecedented fidelities, and their exploitation for fundamental and
metrological applications.Comment: Corrected figures, updated reference
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