Showing papers on "Atom interferometer published in 2012"
TL;DR: In this paper, the effect of losses on the phase sensitivity of the SU(1,1) interferometer for different configurations was studied. And they showed that this type of interferometers is robust against losses that result from an inefficient detection system.
Abstract: We study the effect of losses on the phase sensitivity of the SU(1,1) interferometer for different configurations. We find that this type of interferometer is robust against losses that result from an inefficient detection system. This type of loss only introduces an overall prefactor to the sensitivity but does not change the $1/n$ scaling, where $n$ is the average number of particles inside the interferometer, characteristic of the Heisenberg limit. In addition, we show that under some conditions the SU(1,1) interferometer with coherent state inputs is also robust against internal losses. These results show that the SU(1,1) interferometer is a viable candidate for experimentally reaching the Heisenberg limit with current technology. Possible implementations of this interferometer using four-wave mixing in atomic vapors or an atom interferometer in a spinor Bose-Einstein condensate are compared.
153 citations
TL;DR: In a light-pulse atom interferometer, a tip-tilt mirror is used to remove the influence of the Coriolis force from Earth's rotation and to characterize configuration space wave packets and reach what is to the authors' knowledge the largest space-time area enclosed in any atom interFERometer to date.
Abstract: In a light-pulse atom interferometer, we use a tip-tilt mirror to remove the influence of the Coriolis force from Earth's rotation and to characterize configuration space wave packets. For interferometers with a large momentum transfer and large pulse separation time, we improve the contrast by up to 350% and suppress systematic effects. We also reach what is to our knowledge the largest space-time area enclosed in any atom interferometer to date. We discuss implications for future high-performance instruments.
146 citations
TL;DR: In this article, an atomic Mach?Zehnder-type Sagnac interferometer with a length of 13.7 cm is presented, which covers an area of 19mm2.
Abstract: We report on the realization of a compact atomic Mach?Zehnder-type Sagnac interferometer of 13.7?cm length, which covers an area of 19?mm2 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 2.79?m?s?1, which is split, deflected and combined by driving a Raman transition between the two hyperfine ground states of 87Rb 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 .
94 citations
TL;DR: In this article, the effect of the atomic source's momentum width on the efficiency of Bragg mirrors and beamsplitters and, more generally, on the phase sensitivity of the Bragg pulse atom interferometers was theoretically considered.
Abstract: We theoretically consider the effect of the atomic source's momentum width on the efficiency of Bragg mirrors and beamsplitters and, more generally, on the phase sensitivity of Bragg pulse atom interferometers. By numerical optimization, we show that an atomic cloud's momentum width places a fundamental upper bound on the maximum transfer efficiency of a Bragg mirror pulse, and furthermore limits the phase sensitivity of a Bragg pulse atom interferometer. We quantify these momentum width effects, and precisely compute how mirror efficiencies and interferometer phase sensitivities vary as functions of Bragg order and source type. Our results and methodology allow for an efficient optimization of Bragg pulses and the comparison of different atomic sources, and will help in the design of large momentum transfer Bragg mirrors and beamsplitters for use in atom-based inertial sensors.
92 citations
TL;DR: In this article, a local measurement of gravity combining Bloch oscillations and atom interferometry is presented, where a single retroreflected laser beam performs atom launches and stimulated Raman transitions.
Abstract: We present a local measurement of gravity combining Bloch oscillations and atom interferometry With a falling distance of 08 mm, we achieve a sensitivity of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}\phantom{\rule{028em}{0ex}}\text{g}$ with an integration time of 300 s No bias associated with the Bloch oscillations has been measured A contrast decay with Bloch oscillations has been observed and attributed to the spatial quality of the laser beams A simple experimental configuration has been adopted where a single retroreflected laser beam performs atom launches, stimulated Raman transitions, and Bloch oscillations The combination of Bloch oscillations and atom interferometry can thus be accomplished with an apparatus no more complex than a standard atomic gravimeter
80 citations
TL;DR: In this paper, a new optical concept using plane-parallel plates and spatially separated input beams to minimize the periodic nonlinearities was realized, which was characterized by a comparison with an x-ray interferometer, over a measurement range of 2.2 periods.
Abstract: The PTB developed a new optical heterodyne interferometer in the context of the European joint research project ?Nanotrace?. A new optical concept using plane-parallel plates and spatially separated input beams to minimize the periodic nonlinearities was realized. Furthermore, the interferometer has the resolution of a double-path interferometer, compensates for possible angle variations between the mirrors and the interferometer optics and offers a minimal path difference between the reference and the measurement arm. Additionally, a new heterodyne phase evaluation based on an analogue to digital converter board with embedded field programmable gate arrays was developed, providing a high-resolving capability in the single-digit picometre range. The nonlinearities were characterized by a comparison with an x-ray interferometer, over a measurement range of 2.2 periods of the optical interferometer. Assuming an error-free x-ray interferometer, the nonlinearities are considered to be the deviation of the measured displacement from a best-fit line. For the proposed interferometer, nonlinearities smaller than ?10 pm were observed without any quadrature fringe correction.
78 citations
TL;DR: In this paper, a dual cloud atom interferometer was used to measure the gravity acceleration and gravity gradient simultaneously and with the same instrument, which opens interesting perspectives in geophysical applications.
Abstract: We demonstrate a method to measure the gravitational acceleration with a dual cloud atom interferometer; the use of simultaneous atom interferometers reduces the effect of seismic noise on the gravity measurement. At the same time, the apparatus is capable of accurate measurements of the vertical gravity gradient. The ability to determine the gravity acceleration and gravity gradient simultaneously and with the same instrument opens interesting perspectives in geophysical applications.
68 citations
TL;DR: A high data-rate light-pulse atom interferometer for measuring acceleration that offers a dramatic increase in data rate and demonstrates a path to new applications in highly dynamic environments.
Abstract: We demonstrate a high data-rate light-pulse atom interferometer for measuring acceleration. The device is optimized to operate at rates between 50 Hz to 330 Hz with sensitivities of 0.57μg/Hz to 36.7μg/Hz, respectively. Our method offers a dramatic increase in data rate and demonstrates a path to applications in highly dynamic environments. The performance of the device can largely be attributed to the high recapture efficiency of atoms from one interferometer measurement cycle to another.
59 citations
TL;DR: In this paper, the phase shift induced by the additional laser frequencies was calculated and the model was validated by comparison with experimental measurements on an atom gravimeter, showing that it is possible to reduce this inaccuracy considerably with better control of experimental parameters or with particular interferometer configurations.
Abstract: The use of a Raman laser generated by modulation for a light-pulse atom interferometer allows for a laser system that is compact and robust. However, the additional laser frequencies generated can perturb the atom interferometer. In this article, we present a precise calculation of the phase shift induced by the additional laser frequencies. The model is validated by comparison with experimental measurements on an atom gravimeter. The uncertainty of the phase-shift determination limits the accuracy of our compact gravimeter to $8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\phantom{\rule{0.28em}{0ex}}\text{m}/{\text{s}}^{2}$. We show that it is possible to reduce this inaccuracy considerably with a better control of experimental parameters or with particular interferometer configurations.
58 citations
TL;DR: In this article, the authors reported an experimental test of the topological phase predicted by He and McKellar in 1993 and by Wilkens in 1994: this phase, which appears when an electric dipole propagates in a magnetic field, is connected to the Aharonov-Casher effect by electricmagnetic duality.
Abstract: We report an experimental test of the topological phase predicted by He and McKellar in 1993 and by Wilkens in 1994: this phase, which appears when an electric dipole propagates in a magnetic field, is connected to the Aharonov-Casher effect by electric-magnetic duality. The He-McKellar-Wilkens phase is quite small, at most 27 mrad in our experiment, and this experiment requires the high phase sensitivity of our atom interferometer with spatially separated arms as well as symmetry reversals such as the direction of the electric and magnetic fields. The measured value of the He-McKellar-Wilkens phase differs by 31% from its theoretical value, a difference possibly due to some as yet uncontrolled systematic errors.
56 citations
TL;DR: The longest magic-zero wavelength for ground state potassium atoms is measured to be λ(zero)=768.9712(15) nm, and it is shown how this measurement provides an improved experimental benchmark for atomic structure calculations.
Abstract: Light at a magic-zero wavelength causes a zero energy shift for an atom. We measured the longest magic-zero wavelength for ground state potassium atoms to be λ(zero)=768.9712(15) nm, and we show how this measurement provides an improved experimental benchmark for atomic structure calculations. This λ(zero) measurement determines the ratio of the potassium atom D1 and D2 line strengths with record precision. It also demonstrates a new application for atom interferometry, and we discuss how decoherence will fundamentally limit future measurements of magic-zero wavelengths.
TL;DR: This work presents an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials, yielding insight into decoherence mechanisms.
Abstract: Engineering quantum particle systems, such as quantum simulators and quantum cellular automata, relies on full coherent control of quantum paths at the single particle level. Here we present an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials. The interferometer is constructed from a sequence of discrete operations based on a set of elementary building blocks, which permit composing arbitrary interferometer geometries in a digital manner. We use this modularity to devise a space-time analogue of the well-known spin echo technique, yielding insight into decoherence mechanisms. We also demonstrate mesoscopic delocalization of single atoms with a separation-to-localization ratio exceeding 500; this result suggests their utilization beyond quantum logic applications as nano-resolution quantum probes in precision measurements, being able to measure potential gradients with precision 5 × 10-4 in units of gravitational acceleration g.
TL;DR: New counterpropagating geometries are presented for localizing ultracold atoms in the dark regions created by the interference of Laguerre-Gaussian laser beams and the dark nature of these traps will enable their use as versatile tools for low-decoherence atom interferometry with zero differential light shifts.
Abstract: New counterpropagating geometries are presented for localizing ultracold atoms in the dark regions created by the interference of Laguerre–Gaussian laser beams. In particular dark helices, an “optical revolver,” axial lattices of rings, and axial lattices of ring lattices of rings are considered and a realistic scheme for achieving phase stability is explored. The dark nature of these traps will enable their use as versatile tools for low-decoherence atom interferometry with zero differential light shifts.
TL;DR: Using a network of seismometers and sets of optimal filters, this article implemented a feed-forward control technique to minimize the seismic contribution to multiple interferometric degrees of freedom of the Laser Interferometer Gravitational-wave Observatory interferometers.
Abstract: Using a network of seismometers and sets of optimal filters, we implemented a feed-forward control technique to minimize the seismic contribution to multiple interferometric degrees of freedom of the Laser Interferometer Gravitational-wave Observatory interferometers. The filters are constructed by using the Levinson–Durbin recursion relation to approximate the optimal Wiener filter. By reducing the RMS of the interferometer feedback signals below ~10 Hz, we have improved the stability and duty cycle of the joint network of gravitational wave detectors. By suppressing the large control forces and mirror motions, we have dramatically reduced the rate of non-Gaussian transients in the gravitational wave signal stream.
TL;DR: Using the coherence length of the atom wave packet as a metric, the interferometer is an absolute sensor of acceleration and the technique is sensitive to forces at the level of 3.2×10(-27) N with a spatial resolution at the micron scale.
Abstract: We observe matter wave interference of a single cesium atom in free fall. The interferometer is an absolute sensor of acceleration and we show that this technique is sensitive to forces at the level of 3:2 � 10 � 27 N with a spatial resolution at the micron scale. We observe the build up of the interference pattern one atom at a time in a free-space interferometer where the mean path separation extends far beyond the coherence length of the atom. Using the coherence length of the atom wave packet as a metric, we directly probe the velocity distribution and measure the temperature of a single atom in free fall.
TL;DR: In this article, the authors analyzed the angular and frequency behavior and sensitivity patterns of the responses for each polarization mode of a detector for gravitational wave with arbitrary polarizations predicted in the metric theories of gravity.
Abstract: We analyze detector responses of gravitational wave detectors for gravitational waves with arbitrary polarizations predicted in the metric theories of gravity. We present the general formulas for the frequency responses valid in various interferometric arrangements including Michelson, Delay-Line and Fabry-Perot detectors. We analyze the angular and frequency behavior and the sensitivity patterns of the responses for each polarization mode.
TL;DR: In this article, an asymmetry between the two types of interferometers is pointed out, and it is shown that the nonvanishing, nonrelativistic residue of both effects can be seen in the Kasevich-Chu (K-C) interferometer, while in the Colella-Overhauser-Werner (COW) interFERometer the effects cancel out, leaving no residue, although they could be present in other types of atom interfometers.
Abstract: In recent years there has been enormous progress in matter wave interferometry. The Colella-Overhauser-Werner (COW) type of neutron interferometer and the Kasevich-Chu (K-C) atom interferometer are the prototypes of such devices and the issue of whether they are sensitive to relativistic effects has recently aroused much controversy. We examine the question as to what extent the gravitational redshift and the related twin paradox effect can be seen in both of these atom and neutron interferometers. We point out an asymmetry between the two types of devices. Because of this, the nonvanishing, nonrelativistic residue of both effects can be seen in the neutron interferometer, while in the K-C interferometer the effects cancel out, leaving no residue, although they could be present in other types of atom interferometers. Also, the necessary shifting of the laser frequency (chirping) in the atom interferometer effectively changes the laboratory into a free-fall system, which could be exploited for other experiments.
01 Jan 2012
TL;DR: In this paper, the role of atomic interactions in interferometers based on Bose-condensed atoms is examined, specifically by examining the role played by atomic interactions and the detrimental effects of interactions in the context of atom interferometry.
Abstract: In recent years, atom interferometry has become established as an indispensable tool in both fundamental and applied physics. With present state-of-the-art devices based on thermal atoms reaching limits imposed by the momentum spread of the initial atomic wavepacket, it seems natural to ask whether colder sources such as Bose-Einstein conden sates may prove beneficial in advancing the precision of interferometric measurements. The thesis at hand aims to inform this question, specifically by examining the role played by atomic interactions in interferometers based on Bose-condensed atoms. Interactions can have both advantageous and deleterious consequences in the context of atom inter ferometry. They provide a means to control the momentum width of the condensate, and facilitate the generation of nonclassical squeezed states which may enhance the phase sensitivity beyond the shot noise limit. Conversely, the condensate self-interaction causes mean-field shifts, multimode excitations and phase diffusion which can erode both the precision and the accuracy of an interferometric measurement. The question of when and in which systems the detrimental effects of interactions outweigh the advantages of using Bose-Einstein condensates is an important one, and warrants investigation. This thesis presents experimental studies into the role of interactions in both internaland external-state atom interferometers. As a foundation for these investigations, we de scribe the design and construction of an apparatus for creating Bose-Einstein condensates of the two stable rubidium isotopes in an optical trap. By sympathetic cooling with a 87Rb reservoir, we are able to produce condensates of 85Rb in which the interactions may be adjusted by means of a magnetic Feshbach resonance. The apparatus is compact and ver satile, as demonstrated by rudimentary experiments on spinor condensate dynamics and
TL;DR: Hohensee, Chu, Peters and M\"uller as mentioned in this paper showed that the main result of our paper, namely that atom interferometric gravimeters do not test the gravitational redshift at the Compton frequency, remains valid.
Abstract: Hohensee, Chu, Peters and M\"uller have submitted a comment (arXiv:1112.6039 [gr-qc]) on our paper "Does an atom interferometer test the gravitational redshift at the Compton frequency?", Classical and Quantum Gravity 28, 145017 (2011), arXiv:1009.2485 [gr-qc]. Here we reply to this comment and show that the main result of our paper, namely that atom interferometric gravimeters do not test the gravitational redshift at the Compton frequency, remains valid.
TL;DR: This paper showed that Wolf et al. misapplied both Schiff's conjecture and the results of their own analysis when they concluded that atom interferometers are tests of the weak equivalence principle which only become redshift tests if Schiff conjecture is invalid.
Abstract: We show that Wolf et al’s analysis (2011 Class. Quantum Grav. 28 145017) does not support their conclusions, in particular that there is ‘no redshift effect’ in atom interferometers except in inconsistent dual-Lagrangian formalisms. Wolf et al misapply both Schiff’s conjecture and the results of their own analysis when they conclude that atom interferometers are tests of the weak equivalence principle which only become redshift tests if Schiff’s conjecture is invalid. Atom interferometers are direct redshift tests in any formalism.
TL;DR: It is found that atom interferometer and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g., multiple-arm instruments) to reach interesting sensitivities.
Abstract: We consider a class of proposed gravitational-wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, noninertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g., multiple-arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and, in principle, favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe.
TL;DR: In this paper, the main result of Hohenseeet et al. that atom interferometric gravimeters do not test the gravitational redshift at the Compton frequency, remains valid, and they show that the same result holds also for other types of gravimeters.
Abstract: We reply to a comment by Hohenseeet al on: ‘Does an atom interferometer test the gravitational redshift at the Compton frequency’ and show that the main result of that paper, namely that atom interferometric gravimeters do not test the gravitational redshift at the Compton frequency, remains valid.
19 Mar 2012
TL;DR: A new generation of compact high sensitivity gyroscopes using guided matter-waves on atom chips, able to fulfill the requirements of metrological applications, are proposed.
Abstract: We propose to develop a new generation of compact high sensitivity gyroscopes using guided matter-waves on atom chips, able to fulfill the requirements of metrological applications.
01 Feb 2012
TL;DR: In this article, the authors present a survey of the state-of-the-art methods to solve the problem of how to find the optimal solution for a given set of problems.
Abstract: T. ACCADIA12, F. ACERNESE6ac, F. ANTONUCCI9a, K. G. ARUN11, P. ASTONE9a, G. BALLARDIN2, F. BARONE6ac, M. BARSUGLIA1, TH. S. BAUER14a, M.G. BEKER14a, A. BELLETOILE12, S. BIGOTTA8ab, S. BIRINDELLI15a, M. BITOSSI8a, M. A. BIZOUARD11, M. BLOM14a, C. BOCCARA3, F. BONDU15b, L. BONELLI8ab, R. BONNAND13, V. BOSCHI8a, L. BOSI7a, B. BOUHOU1, S. BRACCINI8a, C. BRADASCHIA8a, A. BRILLET15a, V. BRISSON11, R. BUDZYŃSKI17b, T. BULIK17cd, H. J. BULTEN14ab, D. BUSKULIC12, C. BUY1, G. CAGNOLI4a, E. CALLONI6ab, E. CAMPAGNA4ab, B. CANUEL2, F. CARBOGNANI2, F. CAVALIER11, R. CAVALIERI2, G. CELLA8a, E. CESARINI4b, E. CHASSANDE-MOTTIN1, A. CHINCARINI5, F. CLEVA15a, E. COCCIA10ab, C. N. COLACINO8a, J. COLAS2, A. COLLA9ab, M. COLOMBINI9b, A. CORSI9a, J.-P. COULON15a, E. CUOCO2, S. D’ANTONIO10a, V. DATTILO2, M. DAVIER11, R. DAY2, R. DE ROSA6ab, M. DEL PRETE8ac, L. DI FIORE6a, A. DI LIETO8ab, M. DI PAOLO EMILIO10ac,∗, A. DI VIRGILIO8a, A. DIETZ12, M. DRAGO16cd, V. FAFONE10ab, I. FERRANTE8ab, F. FIDECARO8ab, I. FIORI2, R. FLAMINIO13, J.-D. FOURNIER15a, J. FRANC13, S. FRASCA9ab, F. FRASCONI8a,
03 May 2012
TL;DR: In this paper, a novel planar squeezing uncertainty relation for spin variances in a plane is obtained, and the authors show how to obtain such planar squeezed states using a BEC to minimize interferometric phase-noise at all phase angles simultaneously.
Abstract: We obtain a novel planar squeezing uncertainty relation for spin variances in a plane, and show how to obtain such planar squeezed states using a BEC. These minimize interferometric phase-noise at all phase angles simultaneously.
Dissertation•
01 Jan 2012
TL;DR: In this paper, the static properties and non-equilibrium dynamics of bright solitary waves in atomic Bose-Einstein condensates in the zero-temperature limit were investigated, and the authors showed that a second-order, number-conserving description offers a minimal selfconsistent treatment of the relevant condensate interactions at low temperatures and for moderate non-condensate fractions.
Abstract: In this thesis we investigate the static properties and non-equilibrium dynamics of bright solitary waves in atomic Bose-Einstein condensates in the zero-temperature limit, and we investigate the non-equilibrium dynamics of a driven atomic Bose-Einstein condensate at finite temperature.
Bright solitary waves in atomic Bose-Einstein condensates are non-dispersive and soliton-like matter-waves which could be used in future atom-interferometry experiments. Using the mean-field, Gross-Pitaevskii description, we propose an experimental scheme to generate pairs of bright solitary waves with controlled velocity and relative phase; this scheme could form an important part of a future atom interferometer, and we demonstrate that it can also be used to test the validity of the mean-field model of bright solitary waves. We also develop a method to quantitatively assess how soliton-like static, three-dimensional bright solitary waves are; this assessment is particularly relevant for the design of future experiments.
In reality, the non-zero temperatures and highly non-equilibrium dynamics occurring in a bright solitary wave interferometer are likely to necessitate a theoretical description which explicitly accounts for the non-condensate fraction. We show that a second-order, number-conserving description offers a minimal self-consistent treatment of the relevant condensate -- non-condensate interactions at low temperatures and for moderate non-condensate fractions. We develop a method to obtain a fully-dynamical numerical solution to the integro-differential equations of motion of this description, and solve these equations for a driven, quasi-one-dimensional test system. We show that rapid non-condensate growth predicted by lower-order descriptions, and associated with linear dynamical instabilities, can be damped by the self-consistent treatment of interactions included in the second-order description.
TL;DR: An equal arm heterodyne Mach-Zehnder interferometer has been built on ground to demonstrate the measurement principle of a laser ranging system, which potentially can be used for both SAGM and future GW (gravitational wave) space antennas as discussed by the authors.
Abstract: A Chinese satellite gravity mission called SAGM (Space Advanced Gravity Measurements) is now taken into consideration. To meet its designed requirement, the measurement precision of the laser ranging system used to measure the inter-satellite distance change has to be better than 100nm/Hz1/2 within a broad bandwidth from 0.1 mHz to 1 Hz. An equal arm heterodyne Mach-Zehnder interferometer has been built on ground to demonstrate the measurement principle of a laser ranging system, which potentially can be used for both SAGM and future GW (gravitational wave) space antennas. Because of the equal arm length, the laser frequency noise has been significantly suppressed in the interferometer. Thus, the sensitivity better than 1nm/Hz1/2 in a frequency range of 0.15 mHz–0.375 Hz has been achieved. The result shows that the proposed methodology has very promising feasibility to meet the requirements of SAGM and of GW space antennas as well.
01 Jan 2012
TL;DR: In this article, a non-linear atom interferometer for Bose-Einstein condensates whose linear analog is used for the definition of the time standard is presented. But it is not a quantum interferometry.
Abstract: Interferometry is the most precise measurement technique known today. It is based on interference and therefore on the wave-like nature of the resources – photons or atoms – in the interferometer. As given by the laws of quantum mechanics the granular, particle-like features of the individually independent atoms or photons are responsible for the precision limit – the shot noise limit. However this “classical” bound is not fundamental and it is the aim of quantum metrology to overcome it by employing quantum correlations – entanglement – among the particles. We report on the realization of spin squeezed states suitable for atom interferometry based on two external modes of a Bose-Einstein condensate. We detect manybody entangled states which allow – in principle – for a precision gain of 35% over the shot noise limit in atom interferometry. We demonstrate a novel non-linear atom interferometer for Bose-Einstein condensates whose linear analog – the Ramsey interferometer – is used for the definition of the time standard. Within the non-linear interferometer we detect a large entangled state of 170 inseparable atoms. A measurement with this interferometer outperforms its ideal linear analog by 15% in phase estimation precision showing directly the feasibility of non-linear atom interferometry with Bose-Einstein condensates beyond “classical” precision limits.
TL;DR: In this paper, the true roles of the gravitational charge (mass) and the inertial mass in quantum phases acquired in matter-wave interferometry in a gravitational field were reassessed, and it was shown that the gravitational phase is inversely related to the Compton frequency, invalidating the suggested equivalence to a Compton clock.
TL;DR: In this article, the recoil energy of an atom measured using a perturbative grating-echo atom interferometer (AI) that involves three standing-wave (sw) pulses is described.
Abstract: We describe progress toward a precise measurement of the recoil energy of an atom measured using a perturbative grating-echo atom interferometer (AI) that involves three standing-wave (sw) pulses. With this technique, a perturbing sw pulse is used to shift the phase of excited momentum states---producing a modulation in the contrast of the interference pattern. The signal exhibits narrow fringes that revive periodically at twice the two-photon recoil frequency, $2\omega_q$, as a function of the onset time of the pulse. Experiments are performed using samples of laser-cooled rubidium atoms with temperatures $\lesssim 5$ $\mu$K in a non-magnetic apparatus. We demonstrate a measurement of $\omega_q$ with a statistical uncertainty of 37 parts per $10^9$ (ppb) on a time scale of $\sim 45$ ms in 14 hours. Further statistical improvements are anticipated by extending this time scale and narrowing the signal fringe width. However, the total systematic uncertainty is estimated to be $\sim 6$ parts per $10^6$ (ppm). We describe methods of reducing these systematic errors.