Showing papers on "Atom interferometer published in 2000"

Rotation sensing with a dual atom-interferometer Sagnac gyroscope

Abstract: We reports improvements to our Sagnac effect matter-wave interferometer gyroscope. This device now has a short-term rotation-rate sensitivity of 6×10−10 rad s−1 over 1 s of integration, which is the best publicly reported value to date. Stimulated Raman transitions are used to coherently manipulate atoms from counterpropagating thermal beams, forming two interferometers with opposite rotation phase shifts, allowing rotation to be distinguished from acceleration and laser arbitrary phase. Furthermore, electronically compensating the rotation-induced Doppler shifts of the Raman lasers allows operation at an effective zero rotation rate, improving sensitivity and facilitating sensitive lock-in detection readout techniques. Long-term stability is promising but not yet fully characterized. Potential applications include inertial navigation, geophysical studies and tests of general relativity.

Sensitivity curves for spaceborne gravitational wave interferometers

Abstract: To determine whether particular sources of gravitational radiation will be detectable by a specific gravitational wave detector, it is necessary to know the sensitivity limits of the instrument. These instrumental sensitivities are often depicted ~after averaging over source position and polarization! by graphing the minimal values of the gravitational wave amplitude detectable by the instrument versus the frequency of the gravitational wave. This paper describes in detail how to compute such a sensitivity curve given a set of specifications for a spaceborne laser interferometer gravitational wave observatory. Minor errors in the prior literature are corrected, and the first ~mostly! analytic calculation of the gravitational wave transfer function is presented. Example sensitivity curve calculations are presented for the proposed LISA interferometer. PACS number~s!: 04.80.Nn, 95.55.Ym Advances in modern technology have ushered in an era of large laser interferometers designed to be used in the detection of gravitational radiation, both on the ground and in space. Such projects include the Laser Interferometric Gravitational Wave Observatory ~LIGO! and VIRGO @1,2# ground-based interferometers, and the proposed Laser Interferometer Space Antenna ~LISA! and OMEGA @3,4# spacebased interferometers. As these detectors come on-line, a new branch of astronomy will be created and a radically new view of the Universe is expected to be revealed. With the era of gravitational wave astronomy on the horizon, much effort has been devoted to the problem of categorizing sources of gravitational radiation, and extensive studies are underway to determine what sources will be visible to the various detectors. Typically, the sensitivity of detectors to sources of gravitational radiation has been illustrated using graphs which compare source strengths ~dimensionless strain! to instrument noise as functions of the gravitational wave frequency. Many different types of plots have appeared in the literature, ranging from single plots of spectral density to separate am

Large area light-pulse atom interferometry

Abstract: We report the experimental demonstration of a large area atom interferometer based on extended sequences of light pulses. We characterize the interferometer through measurement of the acceleration due to gravity and demonstrate a threefold enhancement in intrinsic acceleration sensitivity. The technique is applicable to many atom interferometer configurations, including those used for measurement of rotations, gravity gradients, and $\ensuremath{\Elzxh}/m$.

Discriminating a gravitational wave background from instrumental noise in the LISA detector

Abstract: The multiple Doppler readouts available with the Laser Interferometer Space Antenna (LISA) permit simultaneous formation of several observables. All are independent of laser phase fluctuations, but have different couplings to gravitational waves and the various LISA instrumental noises. Comparison, for example, of the Michelson interferometer observable with the fully symmetric Sagnac data-type allows discrimination between a confusion-limited gravitational wave background and instrumental noise.

Precision Rotation Sensing Using Atom Interferometry

Abstract: A rotation-rate sensor was developed using atom interferometry and the Sagnac effect for matter waves. This device has a short-term sensitivity of 6× 10−10 rad/sec for a 1 second integration time, which is the best publicly reported value to date. It has high intrinsic accuracy because it relies on interactions between atoms and laser light that is stabilized to an atomic transition. Long-term stability is promising and characterization is currently underway. Potential applications include inertial navigation, geophysical studies, and general relativity tests such as verification of the Lense-Thirring and geodetic effects. The principle of operation is as follows: A thermal cesium atomic beam crosses three laser interaction regions where two-photon stimulated Raman transitions between cesium ground states transfer momentum to atoms and divide, deflect, and recombine the atomic wavepackets. Rotation induces a phase shift between the two possible trajectories and causes a change in the detected number of atoms with a particular internal state. Counterpropagating atomic beams form two interferometers using shared lasers for common-mode rejection, and the rotation phase shifts have opposite sign since the phase shift is proportional to the vector velocity of the atoms. Therefore, subtracting or adding the interferometer signals discriminates between rotation and transverse acceleration summed with laser arbitrary phase. Furthermore, in the inertial reference frame of the atoms, rotations Doppler-shift the Raman lasers. Adding Raman frequency shifts to cancel these Doppler-shifts allows operation at an effective zero rotation rate, improving sensitivity and bandwidth. Modulating these frequency shifts facilitates sensitive lock-in detection readout techniques.

Shot noise in gravitational-wave detectors with Fabry–Perot arms

Abstract: Shot-noise-limited sensitivity is calculated for gravitational-wave interferometers with Fabry–Perot arms, similar to those being installed at the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Italian–French Laser Interferometer Collaboration (VIRGO) facility. This calculation includes the effect of nonstationary shot noise that is due to phase modulation of the light. The resulting formula is experimentally verified by a test interferometer with suspended mirrors in the 40-m arms.

Atom optics with microfabricated optical elements

Abstract: Summary form only given. The application of microfabricated optical elements and magnetic structures will cause a significant advance in the applicability of atom optics and atom interferometry. The newly emerging field of atom optics with micro-structures (ATOMICS) is directed towards microfabrication of atom optical elements for manipulation, storage, and guiding of neutral atoms as well as miniaturization of incoherent and coherent sources of ultracold atoms. As a second step, the integration of these components with laser sources and efficient detectors in a single-device should be achievable. We expect that the field of ATOMICS will become similarly important for atom optics as photonics is for regular optics. We present several configurations where microfabricated otpical elements are use in atom optics such as atom interferometry and quantum computing.

Magneto-optical control of bright atomic solitons

Abstract: In previous work we showed that bright atomic solitons can arise in spinor Bose-Einstein condensates in the form of gap solitons even for repulsive many-body interactions. Here we further explore the properties of atomic gap solitons and show that their internal structure can be used to both excite them and control their centre-of-mass motion using applied laser and magnetic fields. As an illustration we demonstrate a nonlinear atom-optical Mach-Zehnder interferometer based on gap solitons.

Atomic interference patterns in the transverse plane

Abstract: A quadrupolar static magnetic field used as a phase object in a Stern-Gerlach atom interferometer produces phase shifts proportional to the distance to the zero-field line. As a consequence the transverse intensity profile of the atomic beam beyond the interferometer is modulated by an interference pattern which is a ``phase portrait'' of the field configuration. This pattern---a central bright spot surrounded by annular fringes---can be translated as a whole in any transverse direction by adding a homogeneous field to the quadrupolar field. These effects have been investigated experimentally with a beam of metastable hydrogen atoms ${\mathrm{H}}^{*}(2s),$ either by measuring the atom flux through a fixed slit or by scanning the beam profile through a movable hole. The results are in good agreement with the theoretical predictions.

Observation of phase coherent amplification of atomic matter waves

Abstract: Summary form only given. Atomic matter waves, just like electromagnetic waves, can be focused, reflected, guided and split by the passive atom optical elements of today. However, the key for many applications of RF and light waves lies in the availability of amplifiers. Here, we report the observation of phase coherent amplification of atomic matter waves.

Gyroscopes and gravitational waves

Abstract: The behaviour of a gyroscope at rest in the TT-grid of a gravitational plane wave is analysed. It is shown that spatial frames adapted to the observer carrying the gyroscope (with respect to which the precession must be measured) can be selected in order to have a precession which is dominated (to first order in the dimensionless amplitude h of the wave) only by one polarization state of the wave, giving the gyroscope a sort of filtering property. The discussion is then generalized to the case of a gyroscope in generic geodetic motion in the same background.

Quantum physics of entangled systems: Wave-particle duality and atom-photon molecules

Abstract: One of the cornerstones of quantum physics is the wave nature of matter. It explains experimentally observed effects like interference and diffraction, occurring when an object moves from one place to another along several indistinguishable ways simultaneously. The wave nature disappears when the individual ways are distinguishable. In this case, the particle nature of the object becomes visible. To determine the particle nature quantitatively, the way of the object has to be measured. Here, large progress has been made recently with new techniques, enabling one to investigate single moving atoms in a controlled manner. Two examples are discussed in the following two sections. The first experiment describes an atom interferometer, where the way of the atom is entangled with its internal state. This allows one to explore the origin of wave-particle duality and perform a quantitative test of this fundamental principle. The second experiment reports on the observation of an atom-photon molecule, a bound state between an atom and a single photon. A fascinating aspect of this system is that it makes possible to monitor the motion of a single neutral atom in real time.

Atom interferometer inertial force sensors

Abstract: We report on the progress in the development of high sensitivity and accuracy inertial force sensors which are based on atom interference techniques.

High precision measurement of the topological Aharonov–Casher effect with neutrons

Abstract: The phase shift predicted by Aharonov and Casher (AC) for a magnetic dipole diffracting around a line charge was first observed by Cimmino et al. using a neutron interferometer. A number of subsequent atom interferometry experiments have been performed to observe this effect. These experiments measured the v × E phase shift due to the magnetic field induced in the rest frame of the atom, with no indication of the topological nature of the AC interaction. We intend to perform a high precision AC experiment with neutrons to improve the accuracy of our previous results and to highlight the topological nature of the effect. Finally, we present a novel geometry to achieve a spin-dependent magnetic phase shift.

Exploration of the Fundamentals of Quantum Mechanics by Charged Particle Interferometry

Abstract: An electron biprism interferometer combined with a Wien filter (crossed- field analyzer) proved to be an excellent tool to investigate quantum mechanics: By increasing the excitation of the Wien filter, the laterally separated, coherent wave packets are continuously shifted longitudinally relative to each other. The value of the longitudinal shift for vanishing fringe contrast is identical to the coherence length; by Fourier analyzing the decrease of contrast as a function of the longitudinal shift, the energy spectrum of the particles can be measured in analogy with Michelson's visibility spectroscopy for light. While no ‘which-path’ information is available for full visibility of the fringes (full overlap of the wave packets), ‘which-path’ information increases continuously for increasing longitudinal shift, i.e. with decreasing visibility. Wide separation of the coherent electron waves can be achieved, e.g., by cascading two or more biprisms. Widely separated coherent beams are indispensable for proving the rotationally induced phase shift of electron respectively ion waves (Sagnac effect), the Aharonov-Bohm effect for composite particles (ions), and for experiments on decoherence caused by the irreversible interaction with the electron gas in a conducting plate and by vacuum fluctuations. Last but not least an experiment to show antibunching of free fermions (two particle interference) is in progress at the moment.

Laser interferometer gravitational wave detectors

Abstract: I give a brief introduction on gravitational wave laser interferometers, possible detectable sources from the ground and noise in the detectors

Longitudinal Atom Interferometry

Abstract: A detuned, radiofrequency field interacting with atoms in an atomic beam constitutes a beamsplitter in longitudinal momentum space. Using such beamsplitters, we have constructed a longitudinal atom interferometer in a generalization of Ramsey's classic SOF configuration. This interferometer is well-suited to studying the longitudinal coherence properties of matter-wave beams. We report on two such experiments, including a deconvolution of the longitudinal density matrix of an atomic beam, and a search for longitudinal coherences coming from our supersonic beam source.

Noise Characterization for Laser Interferometer Gravitational Wave Detectors

Abstract: This work incorporates a review of the status, in Australia, of data analysis for gravitational wave detection using laser interferometers, within an overview of the present state of such research in the world generally. In this context, data analysis refers not so much to signal simulation as to what might be called the thorough process of noise characterization and the subsequent, quality-controlled signal extraction. To the extent that problems identified here arise for all currently planned instruments, there is necessarily a global component to the discussion presented. In Australia, there are unique circumstances, associated with attempting to carry out work in gravitational wave detection, which demand also a local aspect to the ensuing discussion.

Detection of Scalar Gravitational Waves

Abstract: In this talk I review recent progresses in the detection of scalar gravitational waves Furthermore, in the framework of the Jordan-Brans-Dicke theory, I compute the signal to noise ratio for a resonant mass detector of spherical shape and for binary sources and collapsing stars Finally I compare these results with those obtained from laser interferometers and from Einsteinian gravity

Optical Modeling of Gravitational Wave Interferometers

Abstract: The aim of this course is to give an idea of the different theoretical and numerical studies that have been carried out for defining the features of present long base line interferometers like Virgo. We first discuss the principles of ideal GW interferometers, we then see that the quality of the Fabry-Perot cavities plays a central role, which justifies a numerical investigation on real optical systems and the corresponding techniques are discussed in the second part.

Potential Sources of Gravitational Wave Emission and Laser Beam Interferometers

Abstract: The properties of potential gravitational wave sources like neutron stars, black holes and binary systems are reviewed, as well as the different contributions (stochastic and continuous) to the gravitational wave background. The detectability of these sources by the present generation of laser beam interferometers, which will be fully operational around 2002, is also considered.

Preparation of single velocity atoms for matter wave interferometry

Abstract: Atoms without ground state splitting, e.g. alkaline earths, are of special interest for atom interferometry and frequency standards due to their small sensitivity to external fields and for BEC and the study of cold collisions due to the simplified theoretical interpretation of their interaction. We demonstrate Maxwell's-demon cooling, a novel method which allows to further cool alkaline earth atoms in one dimension. It consists of three consecutive steps which are repeated several times. First, from a cloud of cooled atoms released from a standard magneto-optical trap a small part of the velocity distribution is selected by excitation on a narrow transition (intercombination transition). Second, these atoms are optically pumped to another long lived state. Third, the ground state velocity distribution is restored by turning on the optical molasses on the strong transition used for the magneto-optical trapping. In addition to Maxwell's thought experiment, where a demon separates the cold atoms from the hot ones, in the novel scheme the hot atoms are furthermore cooled again to the original 3 mK. By repeating these steps slow atoms are accumulated in the excited state. The velocity distribution of the atoms is measured after the cold atoms are decayed to the ground state by recording the Doppler broadening of the intercombination transition.

Analysis of the properties of the time-domain Borde atom interferometry

Abstract: Atom interferometers are expected to be used in various applications, such as precision measurements of inertia force and acceleration of gravity, and of a verification of quantum mechanical phenomena. Conventionally, the method derived by Borde of the evolution matrices of spinors is used to calculate the wave function after interacting with pulses. In order to understand easily the behavior of the interference with various sequences of pulses of a laser beam, we use an analytical method using the geometrical trajectories of the atomic waves. In this method we examine the deflection of atomic trajectory with laser. The amplitude of the interaction with deflections and without deflection is expressed as a function of the pulse area on resonance frequency.