Towards rotation sensing with a single atomic clock

Physical Review A, 2016

We present a model of a spin-squeezed rotation sensor utilising the Sagnac effect in a spin-1 Bose-Einstein condensate in a ring trap. The two input states for the interferometer are seeded using Raman pulses with Laguerre-Gauss beams and are amplified by the bosonic enhancement of spin-exchange collisions, resulting in spin-squeezing and potential quantum enhancement in the interferometry. The ring geometry has an advantage over separated beam path atomic rotation sensors due to the uniform condensate density. We model the interferometer both analytically and numerically for realistic experimental parameters and find that significant quantum enhancement is possible, but this enhancement is partially degraded when working in a regime with strong atomic interactions.

2010

We show that the sensitivity of an atomic clock can be enhanced below the shot-noise level by initially squeezing, and then measuring in output, the population of a single atomic level. This can simplify current experimental protocols which requires squeezing of the relative number of particles of the two populated states. We finally study, as a specific application, the clock sensitivity obtained with a single mode quantum non-demolition measurement.

Atoms

A point source interferometer (PSI) is a device where atoms are split and recombined by applying a temporal sequence of Raman pulses during the expansion of a cloud of cold atoms behaving approximately as a point source. The PSI can work as a sensitive multi-axes gyroscope that can automatically filter out the signal from accelerations. The phase shift arising from the rotations is proportional to the momentum transferred to each atom from the Raman pulses. Therefore, by increasing the momentum transfer, it should be possible to enhance the sensitivity of the PSI. Here, we investigate the degree of enhancement in sensitivity that could be achieved by augmenting the PSI with large momentum transfer (LMT) employing a sequence of many Raman pulses with alternating directions. We analyze how factors such as Doppler detuning, spontaneous emission, and the finite initial size of the atomic cloud compromise the advantage of LMT and how to find the optimal momentum transfer under these limi...

Physical Review A

Bose-Einstein condensates in annular geometries have received significant attention due to their potential use as interferometers for inertial sensing and other applications. We systematically study the critical velocity of a barrier for vortex formation in such a geometry. More significantly, we are able to show that the details of the critical velocity can be captured by a simple analytic solution which can be considered the atomtronic analog of the usual nomographic equations for electronic circuit components. Experimentally useful nomograms can be plotted from the main result of this paper, from the analytic expression abbreviated as , whose accuracy has been validated via full simulations. It is a function of the potential parameters only and it can be used to directly determine parameter regimes for a given application.

IEEE Sensors Journal, 2011

We discuss the basic physics and instrumentation issues related to high-performance physical and inertial sensors based on atomic spectroscopy. Recent work on atomic magnetometers, NMR gyroscopes, and atom interferometers is reviewed, with a focus on precision sensing of electromagnetic and gravitational fields and inertial motion. Atomic sensors have growing relevance to many facets of modern science and technology, from understanding the human brain to enabling precision navigation of moving platforms.

Physical review. A, 1996

A different approach to high-precision measurement of rotation, acceleration, and gravitation is presented. Our Moiré deflectometer is based on geometric propagation of an atomic ͑or molecular͒ beam through a set of three identical gratings. Accelerated movements of the gratings with respect to the atomic beam result in a change of the total transmitted intensity. The device is nondispersive, i.e., atoms with a broad energy distribution and without collimation can be used. Furthermore, rotational and linear ͑gravitational͒ acceleration can easily be distinguished and measured simultaneously. In a certain sense the Moiré deflectometer represents the classical analog to a quantum-mechanical matter-wave interferometer. Experimental results on a test system demonstrate that its sensitivity to rotation and gravitation is already in the range of commercially used inertial sensors. It can be increased straightforwardly by orders of magnitude.

New Journal of Physics, 2009

A scheme for creating NOON-states of the quasi-momentum of ultra-cold atoms has recently been proposed [New J. Phys. 8, 180 (2006)]. This was achieved by trapping the atoms in an optical lattice in a ring configuration and rotating the potential at a rate equal to half a quantum of angular momentum . In this paper we present a scheme for confirming that a NOON-state has indeed been created. This is achieved by spectroscopically mapping out the anti-crossing between the ground and first excited levels by modulating the rate at which the potential is rotated. Finally we show how the NOON-state can be used to make precision measurements of rotation.

Physical review letters, 2006

For the past 50 years, atomic standards based on the frequency of the cesium ground-state hyperfine transition have been the most accurate time pieces in the world. We now report a comparison between the cesium fountain standard NIST-F1, which has been evaluated with an ...

Arxiv preprint arXiv: …, 2010

We report on the observation of nonlinear Faraday rotation with cold atoms at a temperature of ∼100 µK. The observed nonlinear rotation of the light polarization plane is up to 0.1 rad over the 1-mm-size atomic cloud in approximately 10-mG magnetic field. The nonlinearity of rotation results from long-lived coherence of ground-state Zeeman sublevels created by a near-resonant light. The method allows for creation, detection, and control of atomic superposition states. It also allows applications for precision magnetometry with high spatial and temporal resolution.

Review of Scientific Instruments, 2006

We report on the design, characterization, and applications of a sensitive atomic magnetic gradiometer. The device is based on nonlinear magneto-optical rotation in alkali-metal ͑ 87 Rb͒ vapor and uses frequency-modulated laser light. The magnetic field produced by a sample is detected by measuring the frequency of a resonance in optical rotation that arises when the modulation frequency equals twice the Larmor precession frequency of the Rb atoms. The gradiometer consists of two atomic magnetometers. The rotation of light polarization in each magnetometer is detected with a balanced polarimeter. The sensitivity of the gradiometer is 0.8 nG/ Hz 1/2 for near-dc ͑0.1 Hz͒ magnetic fields, with a base line of 2.5 cm. For applications in nuclear magnetic resonance ͑NMR͒ and magnetic resonance imaging ͑MRI͒, a long solenoid that pierces the magnetic shields provides an ϳ0.5 G leading field for the nuclear spins in the sample. Our apparatus is particularly suited for remote detection of NMR and MRI. We demonstrate a point-by-point free induction decay measurement and a spin echo reconstructed with a pulse sequence similar to the Carr-Purcell-Meiboom-Gill pulse. Additional applications and future improvements are also discussed.