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In recent paper, Nowak et al. report a charged wire interferometer for atoms, and employ analytical method to explain the interference patterns [Phys. Rev. Lett.81 (1998) 5792]. In this paper, a numerical calculation with semi-classical method is carried out and the experimental patterns are rebuilt very well. The interference patterns are interpreted by path integral. We also calculate the fringe period for different voltages and the agreement with experiment is more rigorous than the analytical expression. Besides, the fringe visibility of the interference patterns at different applied voltages and degrees is also discussed.

An experiment in Low Earth Orbit (LEO) is proposed to measure components of the Riemann curvature tensor using atom interferometry. We show that the difference in the quantum phase Δϕ of an atom that can travel along two intersecting geodesics is given by mR_0i0j/ℏ times the spacetime volume contained within the geodesics. Our expression for Δϕ also holds for gravitational waves in the long wavelength limit.

It has been known shortly after the introduction of the general relativity theory that the electrostatic Coulomb potential of a point charge supported in a gravitational field is not spherically symmetric and becomes warped in curved space. Under ordinary laboratory conditions, this effect is quite small and has never been directly observed. Surprisingly, this distortion causes the appearance of a hitherto unknown, topologically complex non-central van der Waals force whose detection is well within range of existing trapped atom interferometry techniques. This will allow for an unexpected experimental test of gravity theory by means of quantum-electro-dynamical interatomic forces.

It is well known that an excited atom, placed near a boundary, such as a mirror, undergoes an energy shift due to its interaction with the reflected field. In this paper, we use a generalized Hertz potential to prove that a radiating dipole embedded in a continuously inhomogeneous medium also experiences a position-dependent self-interaction energy shift and a corresponding self-force. Consequently, an excited atom inside a cylindrical cavity embedded in a quasi-homogeneous gravitational field, which acts as an effective "soft" boundary, is shown to experience an effective gravitational acceleration dependent on the atomic quantum state. We predict that excited trapped atom interferometers will thus provide an unexpected tool for ground-based experimentation on radiation backscattering in a Schwarzschild background.

It is shown that, by arranging the atoms in a Bose–Einstein condensate gas within an optical lattice, it is possible to directly verify experimentally that the van der Waals potential energy contributes an effective change to the gravitational mass of the atoms trapped in the array sites equal to that predicted by Einstein's mass–energy equivalency equation, E = m_gc². Some original results of electrostatics and quantum mechanics in curved space are discussed, and strategies to amplify and observe these effects are quantitatively evaluated to illustrate the feasibility of the novel test proposed herein.

Atomic quantum sensors are a major breakthrough in the technology of time and frequency standards as well as ultraprecise sensing and monitoring of accelerations and rotations. They apply a new kind of optics based on matter waves. Today, atomic clocks are the standard for time and frequency measurement at the highest precisions. Inertial and rotational sensors using atom interferometers have already shown similar potential for replacing state-of-the-art sensors in other fields. With Bose–Einstein condensates, also referred as atom lasers, the traditional experiments with atom interferometers can be greatly improved. Testing of fundamental principles, studies of atomic properties, applications as inertial sensors, and measurements of fundamental constants can benefit from the brightness (intensity and small momentum spread) of these coherent sources. In addition, the coherence properties of condensates may allow BEC-based atom interferometers to approach the Heisenberg detection limit. This corresponds to a measurement precision which scales like 1/N for N atoms and not like as for independent measurements on N atoms. We present here the recent progress toward the acheivement of new coherent atomic sources, i.e. atom lasers, that will be use in space-based atom interferometers. We introduce new concepts of atom accelerometers and gyrometers that take advantage of the high collimation and coherence properties of atoms lasers and report on the development of a 0-g coherent atom interferometer (ICE) that will be used to test the ultimate performances of atom accelerometers in space.

The Human Spaceflight, Microgravity, and Exploration (HME) Directorate of the European Space Agency is strongly involved in fundamental physics research. One of the major activities in this field is represented by the ACES (Atomic Clock Ensemble in Space) mission. ACES will demonstrate the high performances of a new generation of atomic clocks in the microgravity environment of the International Space Station (ISS). Following ACES, a vigorous research program has been recently approved to develop a second generation of atomic quantum sensors for space applications: atomic clocks in the optical domain, aiming at fractional frequency stability and accuracy in the low 10^-18 regime; inertial sensors based on matter-wave interferometry for the detection of tiny accelerations and rotations; a facility to study degenerate Bose gases in space. Tests of quantum physics on large distance scales represent another important issue addressed in the HME program. A quantum communication optical terminal has been proposed to perform a test of Bell's inequalities on pairs of entangled photons emitted by a source located on the ISS and detected by two ground stations. In this paper, present activities and future plans will be described and discussed.

There are discernible and fundamental differences between clocks, waves and physical states in classical physics. These fundamental concepts find a common expression in the context of quantum physics in gravitational fields; matter and light waves, quantum states and oscillator clocks become quantum synonymous through the Planck–Einstein–de Broglie relations and the equivalence principle. With this insight, gravitational effects on quantum systems can be simply and accurately analyzed. Apart from providing a transparent framework for conceptual and quantitative thinking on matter waves and quantum states in a gravitational field, we address and resolve with clarity the recent controversial discussions on the important issue of the relation and the crucial difference between gravimetery using atom interferometers and the measurement of gravitational time dilation.

The output of a simple Mach-Zehnder atom interferometer (with light field beam splitters) is studied in order to obtain sensitivity curves for GW signals in the paraxial approximation by using the ABCD matrices techniques and first order perturbation theory for mirroratom interaction; order of magnitude of relevant physical parameters for a realistic GW detector through atom interferometry is deduced, both for single- and coupled-interferometers configurations. Finally a synthetic overview of ongoing activities of the Florence-Urbino group in this field is presented.

Inertial sensors based on atom interferometers have demonstrated extremely high levels of sensitivity thus allowing for accurate measurements of gravitational interactions. Most such sensors employ multi-photon transitions induced by laser fields to manipulate the atomic wavepackets that enter an interferometer. However, this approach cannot totally suppress the contribution of the laser phase noise to the gravitational signal when two sensors are separated by a large distance. In this article, a proof-of-principle experiment for an interferometer operating on the single-photon clock transition of strontium atoms is described. This configuration can suppress the effect of laser phase noise and therefore provides a promising condidate for the detection of low-frequency gravitational waves.

Berry's phase of the atom in the state with a positive or negative g factor for partial cycles of a conical rotating magnetic field was determined using a time-domain atom interferometer. The experimental results show that the solid angle for positive g-factor is ϕ(1-cosθ) and that for a negative g-factor is ϕ(1+cosθ) addition to the reversing the sign.

The following sections are included:

• Introduction

• Atom Interferometry with 24-Photon-Momentum-Transfer Bragg Beam Splitters

• Noise-Immune, Recoil-Sensitive, Large-Area Atom Interferometers

• Very large area atom interferometers by differential optical acceleration

• Towards fundamental physics measurements by atom interferometry
  • Detection of gravitational waves

• References

We present the evaluation of the performances of our cold atom gyroscope. The gyroscope is based on two cold Cesium atom sources, which are manipulated thanks to Raman transitions. We show that the short term sensitivity is limited by the quantum projection noise and the long term sensitivity by wave front distortion of the Raman lasers. A study of the bias and scaling factor completes the characterization of the sensor.

We present a new design for the mobile and robust gravimeter GAIN (Gravimetric Atom Interferometer), which is based on interfering ensembles of laser cooled ⁸⁷Rb atoms in an atomic fountain configuration. With a targeted accuracy of a few parts in 10¹⁰ for the measurement of local gravity, g, this instrument would offer about an order of magnitude improvement in performance over the best currently available absolute gravimeters. Together with the capability to perform measurements directly at sites of geophysical interest, this will open up the possibility for a number of interesting applications. We report on important subsystems of this atom interferometer, including a rack-mounted laser system and a compact vacuum chamber. Furthermore, a high flux 2-dimensional Magneto-optical trap capable of providing up to 10¹² atoms/second and a high-power laser system providing 6.4 W at 780 nm are presented.

We report on the latest determination of the Newtonian gravitational constant G using our atom interferometry gravity gradiometer. After a short introduction on the G measurement issue we will provide a description of the experimental method employed, followed by a discussion of the experimental results in terms of sensitivity and systematic effects. Finally, prospects for future cold atom-based experiments devoted to the measurement of this fundamental constant are reported.

The Human Spaceflight, Microgravity, and Exploration (HME) Directorate of the European Space Agency is strongly involved in fundamental physics research. One of the major activities in this field is represented by the ACES (Atomic Clock Ensemble in Space) mission. ACES will demonstrate the high performances of a new generation of atomic clocks in the microgravity environment of the International Space Station (ISS). Following ACES, a vigorous research program has been recently approved to develop a second generation of atomic quantum sensors for space applications: atomic clocks in the optical domain, aiming at fractional frequency stability and accuracy in the low 10⁻¹⁸ regime; inertial sensors based on matter-wave interferometry for the detection of tiny accelerations and rotations; a facility to study degenerate Bose gases in space. Tests of quantum physics on large distance scales represent another important issue addressed in the HME program. A quantum communication optical terminal has been proposed to perform a test of Bell's inequalities on pairs of entangled photons emitted by a source located on the ISS and detected by two ground stations. In this paper, present activities and future plans will be described and discussed.

Atomic quantum sensors are a major breakthrough in the technology of time and frequency standards as well as ultraprecise sensing and monitoring of accelerations and rotations. They apply a new kind of optics based on matter waves. Today, atomic clocks are the standard for time and frequency measurement at the highest precisions. Inertial and rotational sensors using atom interferometers have already shown similar potential for replacing state-of-the-art sensors in other fields. With Bose–Einstein condensates, also referred as atom lasers, the traditional experiments with atom interferometers can be greatly improved. Testing of fundamental principles, studies of atomic properties, applications as inertial sensors, and measurements of fundamental constants can benefit from the brightness (intensity and small momentum spread) of these coherent sources. In addition, the coherence properties of condensates may allow BEC-based atom interferometers to approach the Heisenberg detection limit. This corresponds to a measurement precision which scales like 1/N for N atoms and not like as for independent measurements on N atoms. We present here the recent progress toward the acheivement of new coherent atomic sources, i.e. atom lasers, that will be use in space-based atom interferometers. We introduce new concepts of atom accelerometers and gyrometers that take advantage of the high collimation and coherence properties of atoms lasers and report on the development of a 0-g coherent atom interferometer (ICE) that will be used to test the ultimate performances of atom accelerometers in space.

We describe our efforts to study the physics of the fractional quantum Hall effect using ultracold quantum gases in an optical lattice and to perform precision measurements using large-area atom interferometry.

We use Bloch oscillations to coherently transfer many photon momenta to atoms. Then we can measure accurately the recoil velocity ħk/m and deduce the fine structure constant α. The velocity variation due to Bloch oscillations is measured using atom interferometry. This method yields a value of the fine structure constant α^-1 = 137.035 999 45 (62) with a relative uncertainty of about 4.5 × 10^-9.

Bose-Einstein condensates have long been considered the most appropriate source for interferometry with matter waves, due to their maximal coherence properties. However, the realization of practical interferometers with condensates has been so far hindered by the presence of the natural atom-atom interaction, which dramatically affects their performance. We describe here the realization of a lattice-based interferometer based on a Bose-Einstein condensate where the contact interaction can be tuned by means of a Feshbach resonance, and eventually reduced towards zero. We observe a strong increase of the coherence time of the interferometer with vanishing scattering length, and see evidence of the effect of the weak magnetic dipole-dipole interaction. Our observations indicate that high-sensitivity atom interferometry with Bose-Einstein condensates is feasible, via a precise control of the interactions.