Showing papers on "Atom interferometer published in 2007"
17 Jun 2007
TL;DR: An experiment in which quantum jumps in the photon number are observed and a similar QND procedure to mesoscopic fields with tens of photons is applied, which should open new perspectives for the exploration of the quantum-to-classical boundary.
Abstract: Summary form only given. A microscopic system under continuous observation exhibits at random times sudden jumps between its states. Quantum jumps of trapped massive particles (electrons, ions or molecules) have already been observed, which is not the case of the jumps of light quanta. Here we report on the first observation of photon number quantum jumps. Microwave photons are stored in a superconducting cavity for times in the second range. They are repeatedly probed by a stream of non-absorbing atoms. An atom interferometer measures the atomic dipole phase shift induced by the non-resonant cavity field, so that the final atom state reveals directly the presence of a single photon in the cavity. Sequences of hundreds of atoms highly correlated in the same state, are interrupted by sudden state-switchings. These telegraphic signals record, for the first time, the birth, life and death of individual photons. Applying a similar QND procedure to mesoscopic fields with tens of photons opens new perspectives for the exploration of the quantum to classical boundary.
561 citations
TL;DR: The Newtonian constant of gravity is measured using a gravity gradiometer based on atom interferometry using the differential acceleration of two samples of laser-cooled Cs atoms to investigate the change in gravitational field when a well-characterized Pb mass is displaced.
Abstract: We measured the Newtonian constant of gravity, G , using a gravity gradiometer based on atom interferometry. The gradiometer measures the differential acceleration of two samples of laser-cooled Cs atoms. The change in gravitational field along one dimension is measured when a well-characterized Pb mass is displaced. Here, we report a value of G = 6.693 × 10–11 cubic meters per kilogram second squared, with a standard error of the mean of ±0.027 × 10–11 and a systematic error of ±0.021 × 10–11 cubic meters per kilogram second squared. The possibility that unknown systematic errors still exist in traditional measurements makes it important to measure G with independent methods.
474 citations
TL;DR: An experiment is proposed that will initially test the equivalence principle, and probe general relativistic effects - such as the nonlinear three-graviton coupling, the gravity of an atom's kinetic energy, and the falling of light - to several decimals.
Abstract: The unprecedented precision of atom interferometry will soon lead to laboratory tests of general relativity to levels that will rival or exceed those reached by astrophysical observations We propose such an experiment that will initially test the equivalence principle to 1 part in 10(15) (300 times better than the current limit), and 1 part in 10(17) in the future It will also probe general relativistic effects - such as the nonlinear three-graviton coupling, the gravity of an atom's kinetic energy, and the falling of light - to several decimals In contrast with astrophysical observations, laboratory tests can isolate these effects via their different functional dependence on experimental variables
306 citations
TL;DR: A rotationally sensitive (Sagnac) geometry for a guided atom interferometer by propagating the split condensates is demonstrated and enhanced coherence time is attributed to number squeezing of the initial state.
Abstract: We measure the relative phase of two Bose-Einstein condensates confined in a radio frequency induced double-well potential on an atom chip. We observe phase coherence between the separated condensates for times up to $\ensuremath{\sim}200\text{ }\text{ }\mathrm{ms}$ after splitting, a factor of 10 longer than the phase diffusion time expected for a coherent state for our experimental conditions. The enhanced coherence time is attributed to number squeezing of the initial state by a factor of 10. In addition, we demonstrate a rotationally sensitive (Sagnac) geometry for a guided atom interferometer by propagating the split condensates.
280 citations
TL;DR: The controlled loading and measurement of number-squeezed states and Poisson states of atoms in individual sites of a double well optical lattice provides a means to detect the presence of empty lattice sites, an important and so far unmeasured factor in determining the purity of a Mott state.
Abstract: We describe the controlled loading and measurement of number-squeezed states and Poisson states of atoms in individual sites of a double well optical lattice. These states are input to an atom interferometer that is realized by symmetrically splitting individual lattice sites into double wells, allowing atoms in individual sites to evolve independently. The two paths then interfere, creating a matter-wave double-slit diffraction pattern. The time evolution of the double-slit diffraction pattern is used to measure the number statistics of the input state. The flexibility of our double well lattice provides a means to detect the presence of empty lattice sites, an important and so far unmeasured factor in determining the purity of a Mott state.
131 citations
TL;DR: A "folded figure 8" interfering configuration for creating a compact, large-area atom gyroscope with multiple-turn interfering paths is demonstrated.
Abstract: We demonstrate area-enclosing atom interferometry based on a moving guide. Light pulses along the free-propagation direction of a magnetic guide are applied to split and recombine the confined atomic matter-wave, while the atoms are translated back and forth along a second direction in 50 ms. The interferometer is estimated to resolve 10 times the earth rotation rate per interferometry cycle. We demonstrate a "folded figure 8" interfering configuration for creating a compact, large-area atom gyroscope with multiple-turn interfering paths.
103 citations
TL;DR: In this article, the recombination of two split Bose-Einstein condensates on an atom chip is shown to result in heating which depends on the relative phase of the two Condensates.
Abstract: The recombination of two split Bose-Einstein condensates on an atom chip is shown to result in heating which depends on the relative phase of the two condensates. This heating reduces the number of condensate atoms between 10% and 40% and provides a robust way to read out the phase of an atom interferometer without the need for ballistic expansion. The heating may be caused by the dissipation of dark solitons created during the merging of the condensates.
79 citations
TL;DR: In this article, the authors investigated the possibility of using atom interferometers to detect gravitational waves, and discussed the interaction of gravitational waves with an atom inter-ferometer and analyzed possible schemes.
Abstract: We investigate the possibility of using atom interferometers to detect gravitational waves. We discuss the interaction of gravitational waves with an atom interferometer and analyse possible schemes.
71 citations
TL;DR: In this article, the authors studied the effect of laser frequency noise on the performance of atom interferometers based on two photon transitions and showed that the delay induced by the difference of the laser beams paths makes the interferometer sensitive to fluctuations of the frequency of the lasers.
Abstract: In atom interferometers based on two photon transitions, the delay induced by the difference of the laser beams paths makes the interferometer sensitive to the fluctuations of the frequency of the lasers. We first study, in the general case, how the laser frequency noise affects the performance of the interferometer measurement. Our calculations are compared with the measurements performed on our cold atom gravimeter based on stimulated Raman transitions. We finally extend this study to the case of cold atom gradiometers.
59 citations
TL;DR: In this paper, a double-stage magneto-optical trap (MOT) design is proposed for high precision dual-atom interferometers, where accumulated atoms are precisely launched in a horizontal moving molasses.
Abstract: We present a compact {sup 87}Rb atomic source for high precision dual atom interferometers. The source is based on a double-stage magneto-optical trap (MOT) design, consisting of a two-dimensional (2D) -MOT for efficient loading of a 3D-MOT. The accumulated atoms are precisely launched in a horizontal moving molasses. Our source generates a high atomic flux (>10{sup 10} atoms/s) with precise and flexibly tunable atomic trajectories as required for high resolution Sagnac atom interferometry. We characterize the performance of the source with respect to the relevant parameters of the launched atoms, i.e., temperature, absolute velocity, and pointing, by utilizing time-of-flight techniques and velocity selective Raman transitions.
52 citations
TL;DR: In this paper, it is shown that, from a particular high order gravity theory known in the literature, it is possible to produce, in the linearized approach, particles which can be seen like massive scalar modes of gravitational waves, and the response of interferometers to such particles is analyzed.
Abstract: The strict analogy between scalar–tensor theories of gravity and high order gravity is well known in the literature. In this paper it is shown that, from a particular high order gravity theory known in the literature, it is possible to produce, in the linearized approach, particles which can be seen like massive scalar modes of gravitational waves, and the response of interferometers to such particles is analysed. The presence of the mass generates a longitudinal force in addition of the transverse one which is appropriate to the massless gravitational waves and the response of an arm of an interferometer to this longitudinal effect in the frame of a local observer is computed. This longitudinal response function is directly connected to the function of the Ricci scalar in the particular action of this high order theory. Important consequences from a theoretical point of view could arise from this approach, because it opens up the possibility of using the signals seen from interferometers to understand which is the correct theory of gravitation.The presence of the mass could also have important applications in cosmology because of the fact that gravitational waves can have mass and could give a contribution to the dark matter of the Universe.
TL;DR: In this article, a scheme for the generation of highly non-classical entangled field states of the type in the cavity QED scenario was proposed, which utilizes an atomic analogue of the Mach-Zehnder interferometer having a quantized field in the high-Q cavity containing a superposition of zero and one photon.
Abstract: We propose a scheme for generation of highly non-classical entangled field states of the type in the cavity QED scenario. The scheme utilizes an atomic analogue of the Mach–Zehnder interferometer having a quantized field in the high-Q cavity containing a superposition of zero and one photon that acts as the first beam splitter. The probability for production of the desired states may approach a value close to unity with high fidelity under prevailing experimental conditions.
TL;DR: The phase coherent splitting of Bose-Einstein condensates by means of a phase grating produced near the surface of a microelectronic chip is reported and a reproducible phase relation between the diffraction orders is shown with an uncertainty limited by the resolution of the diffractions grating.
Abstract: We report the phase coherent splitting of Bose-Einstein condensates by means of a phase grating produced near the surface of a microelectronic chip. A lattice potential with a period of $4\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ is generated by the superposition of static and oscillating magnetic fields. Precise control of the diffraction is achieved by controlling the currents in the integrated conductors. The interference of overlapping diffraction orders is observed after 8 ms of propagation in a harmonic trap and subsequent ballistic expansion of the atomic ensemble. By analyzing the interference pattern we show a reproducible phase relation between the diffraction orders with an uncertainty limited by the resolution of the diffraction grating.
TL;DR: In this article, the authors review recent experimental progress towards quan- tum information processing and precision force sensing using finite-length atoms in micro traps, including the implementation of single-qubit operation in both, optical and magnetic micro traps.
Abstract: We review recent experimental progress towards quan- tum information processing and precision force sensing using neu- tral atoms in micro traps. Microscopic potential structures as gen- erated by optical or electronic microstructures (micro traps) allow for a versatile manipulation of quantum states of atoms and of ul- tracold atomic quantum gases. Most recent experimental results include the implementation of single-qubit-operations in both, optical and magnetic micro traps, as well as in the demonstration of matter-wave interferometer using Bose-Einstein condensates coherently split in micro traps.
TL;DR: In this article, the authors used a two-port interferometer with soliton states of a Bose-Einstein condensate to measure magnetic field gradient with a precision of 10-2 pT/cm.
Abstract: We propose the precision measurement of both angular rotation and of the gradient magnetic of a field based on the use of matter wave interferometers with soliton states of a Bose-Einstein condensate (BEC). We consider the formation of these soliton states in a BEC with negative scattering length by an optical lattice produced by two counterpropagating laser beams. We determine the parameters of both the initial condensate and the optical radiation necessary for the formation of coherent solitons. We demonstrate that this interferometer can be used to measure magnetic field gradient with a precision of 10-2 pT/cm. Our calculations show that the sensitivity of a gyroscope based on a ring, two-port matter wave interferometer can achieve 2.6×10-7 rad s-1. The precision of this method is more than ten times greater than in that of rotating interferometer with cooled atoms.
Patent•
11 Dec 2007TL;DR: In this paper, the authors present a disclosure of multiple degree-of-freedom interferometers for monitoring linear and angular displacements of a measurement object with compensation for variations in the optical properties of a gas in the interferometer measurement and/or reference beam paths.
Abstract: The disclosure features multiple degree-of-freedom interferometers (e.g., non-dispersive interferometers) for monitoring linear and angular (e.g., pitch and/or yaw) displacements of a measurement object with compensation for variations in the optical properties of a gas in the interferometer measurement (and/or reference) beam paths. The disclosure also features interferometry systems that feature an array of interferometers (e.g., including one or more multiple degree-of-freedom interferometer), each configured to provide different information about variations in the optical properties of the gas in the system. Multiple degree-of-freedom interferometers are also referred to as multi-axis interferometers.
TL;DR: In this article, a realization of a Sagnac-type interferometer with cold atoms is presented. Butler et al. showed that cold rubidium atoms are prepared in a magneto-optical trap and are pushed by resonant laser pulse to form slow atomic beam.
Abstract: Cold-matter-wave Sagnac interferometers possess many advantages over their thermal atomic beam counterparts when they are used as precise inertial sensors. We report a realization of a Sagnac-type interferometer with cold atoms. Cold rubidium atoms are prepared in a magneto-optical trap and are pushed by resonant laser pulse to form slow atomic beam. In the interference region, atomic wave packets are coherently manipulated using pi/2 - pi - pi/2 Raman pulse sequences. Interference fringes with maximum contrast of 37% are observed experimentally.
11 Mar 2007
TL;DR: The I.C.E. (Interferometrie Coherente pour l'Espace) interferometer as mentioned in this paper uses degenerate gases for low-velocity atomic sources in space-borne experiments.
Abstract: The accuracy and precision of current atom-interferometric inertialsensors rival state-of-the-art conventional devices using artifact-based test masses . Atomic sensors are well suited for fundamental measurements of gravito-inertial fields. The sensitivity required to test gravitational theories can be achieved by extending the baseline of the interferometer. The I.C.E. (Interferometrie Coherente pour l'Espace) interferometer aims to achieve long interrogation times in compact apparatus via reduced gravity. We have tested a cold-atom source during airplane parabolic flights. We show that this environment is compatible with free-fall interferometric measurements using up to 4 second interrogation time. We present the next-generation apparatus using degenerate gases for low release-velocity atomic sources in space-borne experiments.
TL;DR: The method will enable direct and precise measurements of ultracold atom–atom interactions, and may be used to place stringent limits on the time variations of fundamental constants.
Abstract: The collision of two ultracold atoms results in a quantum mechanical superposition of the two possible outcomes: each atom continues without scattering, and each atom scatters as an outgoing spherical wave with an s-wave phase shift. The magnitude of the s-wave phase shift depends very sensitively on the interaction between the atoms. Quantum scattering and the underlying phase shifts are vitally important in many areas of contemporary atomic physics, including Bose-Einstein condensates, degenerate Fermi gases, frequency shifts in atomic clocks and magnetically tuned Feshbach resonances. Precise experimental measurements of quantum scattering phase shifts have not been possible because the number of scattered atoms depends on the s-wave phase shifts as well as the atomic density, which cannot be measured precisely. Here we demonstrate a scattering experiment in which the quantum scattering phase shifts of individual atoms are detected using a novel atom interferometer. By performing an atomic clock measurement using only the scattered part of each atom's wavefunction, we precisely measure the difference of the s-wave phase shifts for the two clock states in a density-independent manner. Our method will enable direct and precise measurements of ultracold atom-atom interactions, and may be used to place stringent limits on the time variations of fundamental constants.
TL;DR: A real-time differential phase-front detector sensitive to better than 3 mrad rms, which corresponds to a precision of approximately 500 pm, developed as part of the research for the Laser Interferometer Space Antenna Technology Package interferometer.
Abstract: We present a real-time differential phase-front detector sensitive to better than 3 mrad rms, which corresponds to a precision of approximately 500 pm. This detector performs a spatially resolving measurement of the phase front of a heterodyne interferometer, with heterodyne frequencies up to approximately 10 kHz. This instrument was developed as part of the research for the Laser Interferometer Space Antenna Technology Package interferometer and will assist in the manufacture of its flight model. Because of the advantages this instrument offers, it also has general applications in optical metrology.
Journal Article•
TL;DR: In this article, an optical-fiber interferometer was used to detect the source of the gravitational wave signals, and the frequency spectrum of the signals showed a pink noise spectrum, from essentially 0 to 0.1 Hz.
Abstract: Preliminary results from an optical-fiber gravitational wave interferometric detector are reported. The detector is very small, cheap and simple to build and operate. It is assembled from readily available opto-electronic components. A parts list is given. The detector can operate in two modes: one in which only instrument noise is detected, and data from a 24 hour period is reported for this mode, and in a 2nd mode in which the gravitational waves are detected as well, and data from a 24 hour period is analysed. Comparison shows that the instrument has a high S/N ratio. The frequency spectrum of the gravitational waves shows a pink noise spectrum, from 0 to 0.1 Hz. Preliminary results from an optical-fiber gravitational wave interferometric detector are reported. The detector is very small, cheap and simple to build and operate, and is shown in Fig. 1. It is assembled from readily available opto-electronic components, and is suitable for amateur and physics undergraduate laboratories. A parts list is given. The detector can operate in two modes: one in which only instrumental noise is detected, and the 2nd in which the gravitational waves are detected as well. Comparison shows that the instrument has a high S/N ratio. The frequency spectrum of the gravitational waves shows a pink noise spectrum, from essentially 0 to 0.1 Hz. The interferometer is 2nd order in and is analogous to a Michelson interferometer. Michelson interferometers in vacuum mode cannot detect the lightspeed anisotropy e ect or the gravitational waves manifesting as light-speed anisotropy fluctuations. The design and operation as well as preliminary data analysis are reported here so that duplicate detectors may be constructed to study correlations over various distances. The source of the gravitational waves is unknown, but a 3D multi-interferometer detector will soon be able to detect directional characteristics of the waves.
TL;DR: In this article, the passage of ultracold two-level atoms in a waveguide through two separated laser fields for the nonresonant case was examined and the implications of the atomic quantised motion change dramatically the behaviour of the interference fringes compared to the semiclassical description of this optical Ramsey interferometer using two-channel recurrence relations.
Abstract: We examine the passage of ultracold two-level atoms in a waveguide through two separated laser fields for the nonresonant case We show that implications of the atomic quantised motion change dramatically the behaviour of the interference fringes compared to the semiclassical description of this optical Ramsey interferometer Using two-channel recurrence relations we are able to express the double-laser scattering amplitudes by means of the single-laser ones and to give explicit analytical results When considering slower and slower atoms, the transmission probability of the system changes considerably from an interference behaviour to a regime where scattering resonances prevail This may be understood in terms of different families of trajectories that dominate the overall transmission probability in the weak field or in the strong field limit
TL;DR: This partial implementation of a recently proposed optical configuration using bidirectional Mach-Zehnder interferometers has confirmed the essential feature of DFI: the combination of two MZI signals can be carried out in a way that cancels displacement noise of the mirrors while maintaining gravitational-wave signals.
Abstract: We have demonstrated displacement- and frequency-noise-free laser interferometry (DFI) by partially implementing a recently proposed optical configuration using bidirectional Mach-Zehnder interferometers (MZIs). This partial implementation, the minimum necessary to be called DFI, has confirmed the essential feature of DFI: the combination of two MZI signals can be carried out in a way that cancels displacement noise of the mirrors while maintaining gravitational-wave signals. The attained maximum displacement-noise suppression was 45 dB.
TL;DR: In this article, the authors measured the fringe visibility as a function of the applied magnetic field gradient applied to an atom interferometer induced a M-dependent phase shift which results in a series of decays and revivals of fringe visibility, and tested the isotopic selectivity and velocity selective character of Bragg diffraction for different diffraction orders as well as the effect of optical pumping of incoming atoms.
Abstract: A magnetic field gradient applied to an atom interferometer induces a M-dependent phase shift which results in a series of decays and revivals of the fringe visibility. Using our lithium atom interferometer based on Bragg laser diffraction, we have measured the fringe visibility as a function of the applied gradient. We have thus tested the isotopic selectivity of the interferometer, the velocity selective character of Bragg diffraction for different diffraction orders as well as the effect of optical pumping of the incoming atoms. All these observations are qualitatively understood but a quantitative analysis requires a complete model of the interferometer.
TL;DR: In this article, a common misconception about laser interferometric detectors of gravitational waves was clarified with the help of a direct calculation of the wavelength of laser light and the length of an interferometer's arm.
Abstract: A common misconception about laser interferometric detectors of gravitational waves purports that, because the wavelength of laser light and the length of an interferometer’s arm are both stretched by a gravitational wave, no effect should be visible, invoking an analogy with cosmological redshift in an expanding universe. The issue is clarified with the help of a direct calculation.
TL;DR: In this article, it was shown that the coherence length of a cold atomic wave packet remains constant while the packet's overall physical size increases in time, even when the packet is prepared in a regime where de Broglie wavelengths are much more comparable to coherence lengths.
Abstract: We give experimental evidence to confirm that the coherence length of a cold atomic wave packet remains constant while the packet's overall physical size increases in time. Doppler sensitive atom interferometry allows for atoms to be prepared in a regime where de Broglie wavelengths are much more comparable to coherence lengths than in a thermal regime. Atomic wave packet interactions are a function of coherence length which is determined by the initial velocity spread of the atom wave.
01 May 2007
TL;DR: In this paper, the sensitivity of a Ramsey-Borde interferometer to a gravitational wave was compared to the one of light wave interferometers, and it was shown that the latter could compete with the latter.
Abstract: We comment the controversy that followed the article of Chiao & Speliotopoulos [1] about the sensitivity of an atom interferometer to a gravitational wave. Then we report our results [2] on the sensitivity of a Ramsey-Borde interferometer to a gravitational wave, and we compare it to the one of light wave interferometers. We find that atom interferometers could compete with space based light wave interferometers.
Dissertation•
01 Jan 2007
TL;DR: Mavalvala et al. as discussed by the authors described a frequency resolving wavefront sensor, called the phase camera, which was used on the interferometer to examine the heating effects and corrections of the thermal compensation system.
Abstract: Over the last several years the Laser Interferometer Gravitational Wave Observatory (LIGO) has been making steady progress in improving the sensitivities of its three interferometers, two in Hanford, Washington, and one in Livingston, Louisiana. These interferometers have reached their target design sensitivities and have since been collecting data in their fifth science run for well over a year. On the way to increasing the sensitivities of the interferometers, difficulties with increasing the input laser power, due to unexpectedly high optical absorption, required the installation of a thermal compensation system. We describe a frequency resolving wavefront sensor, called the phase camera, which was used on the interferometer to examine the heating effects and corrections of the thermal compensation system. The phase camera was also used to help understand an output mode cleaner which was temporarily installed on the Hanford 4 km interferometer. Data from the operational detectors was used to carry out two continuous gravitational wave searches directed at isolated neutron stars. The first, targeted RX J1856.5-3754, now known to be outside the LIGO detection band, was used as a test of a new multiinterferometer search code, and compared it to a well tested single interferometer search code and data analysis pipeline. The second search is a targeted search directed at the Crab pulsar, over a physically motivated parameter space, to complement existing narrow time domain searches. The parameter space was chosen based on computational constraints, expected final sensitivity, and possible frequency differences due to free precession and a simple two component model. An upper limit on the strain of gravitational radiation from the Crab pulsar of 1.6 x 10-24 was found with 95% confidence over a frequency band of 6 x 103 Hz centered on twice the Crab pulsar's electromagnetic pulse frequency of 29.78 Hz. At the edges of the parameter space, this search is approximately 105 times more sensitive than the time domain searches. This is a preliminary result, presently under review by the LIGO Scientific Collaboration. Thesis Supervisor: Nergis Mavalvala Title: Associate Professor of Physics
16 Sep 2007
TL;DR: In this paper, the authors describe their efforts to transition atom optic sensors from the laboratory into the field for navigation, guidance, pointing and geophysical exploration, and describe the transition process.
Abstract: The exquisite accuracies of atom optic sensors hold great promise for demanding applications in navigation, guidance, pointing and geophysical exploration. We describe our efforts to transition these sensors from the laboratory into the field.