Observation of Larmor spin precession of laser-cooled Rb atoms via paramagnetic Faraday rotation

Isayama, T.; Takahashi, Yoshiro; Tanaka, N.; Toyoda, K.; Ishikawa, Kiyoshi; Yabuzaki, T.

doi:10.1103/physreva.59.4836

Cited by 42 publications

(40 citation statements)

References 18 publications

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“…In this case, the atoms fall completely out of the probe beam detection window within 25 ms, with a 1/e decay time of 13 ms, similar to that reported in Ref. [2]. The signals in Fig.…”

Section: Introductionsupporting

confidence: 84%

Faraday spectroscopy of atoms confined in a dark optical trap

2008

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We demonstrate Faraday spectroscopy with high duty cycle and sampling rate using atoms confined to a blue-detuned optical trap. Our trap consists of a crossed pair of high-charge-number hollow laser beams, which forms a dark, box-like potential. We have used this to measure transient magnetic fields in a 500µm-diameter spot over a 400 ms time window with nearly unit duty cycle at a 500 Hz sampling rate. We use these measurements to quantify and compensate time-varying magnetic fields to ≈10 nT per time sample.

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“…In this case, the atoms fall completely out of the probe beam detection window within 25 ms, with a 1/e decay time of 13 ms, similar to that reported in Ref. [2]. The signals in Fig.…”

Section: Introductionsupporting

confidence: 84%

Faraday spectroscopy of atoms confined in a dark optical trap

2008

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“…Faraday measurements have opened new perspectives in quantum metrology [1], quantum information [2], non-linear mean-field [3] and many-body [4] systems; and have potential for probing strongly-correlated systems [5]. The Faraday interface has been applied to progressively colder systems: magneto-optical traps [6], dark- [7] and bright-optical dipole traps [4,[8][9][10][11][12], and Bose-Einstein condensates (BEC) [3,13]. However, the classical backaction of the Faraday probe perturbs atomic motional and spin degrees of freedom, limiting and confounding measurements of emergent phenomena or weak external fields at ultracold temperatures.…”

Section: Introductionmentioning

confidence: 99%

Continuous Faraday measurement of spin precession without light shifts

et al. 2017

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We describe a dispersive Faraday optical probe of atomic spin which performs a weak measurement of spin projection of a quantum gas continuously for more than one second. To date focusing bright far-off-resonance probes onto quantum gases has proved invasive, due to strong scalar and vector light shifts exerting dipole and Stern-Gerlach forces. We show that tuning the probe near the magiczero wavelength at 790 nm between the fine-structure doublet of 87 Rb cancels the scalar light shift, and careful control of polarization eliminates the vector light shift. Faraday rotations due to each fine-structure line reinforce at this wavelength, enhancing the signal-to-noise ratio for a fixed rate of probe-induced decoherence. Using this minimally-invasive spin probe we perform microscale atomic magnetometry at high temporal resolution. Spectrogram analysis of the Larmor precession signal of a single spinor Bose-Einstein condensate measures a time-varying magnetic field strength with 1 µG accuracy every 5 ms; or equivalently makes > 200 successive measurements each at 10 pT/ √ Hz sensitivity.

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“…Magnetic field sensing with cold atoms utilizing Larmor precession of alkali atoms in a magnetic field has been discussed in: MOT [10], Bose-Einstein condensate [11,12] and an optical dipole trap [13]. Our measurements apply a different principle: rather than measuring Larmor frequency (single atom quantity), we measure rotation of a polarization plane (a cumulative effect over the whole sample), which may offer higher accuracy in very low magnetic fields.…”

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confidence: 99%

Nonlinear Faraday rotation and detection of superposition states in cold atoms

et al. 2010

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We report on the first 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. PACS numbers: 33.57.+c, 42.50.Dv, 42.50.Gy, 32.80.Xx The linear Faraday rotation (LFR) of the polarization plane of light propagating in the medium is a well known consequence of optical anisotropy caused by a longitudinal magnetic field. For thermal gases the Doppler effect broadens the range of the magnetic fields where the effect is visible and reduces the size of the maximum rotation relative to atoms at rest. The use of cold atoms with their Doppler width narrower than the natural linewidth distinguishes this situation from experiments at room temperature. The experiments on LFR with cold atoms were performed in a magneto-optical trap (MOT) [1][2][3], and in an optical dipole trap [4].Application of strong, near-resonant laser light may result in the creation of coherent superpositions of Zeeman sublevels of an atomic ground state. Such superpositions (Zeeman coherences) are known to be responsible for a variety of coherent phenomena in lightmatter interaction, like coherent population trapping [5], electromagnetically-induced transparency [6], nonlinear magneto-optical rotation or nonlinear Faraday rotation (NFR) [7] and their interplay [8]. Superposition states are also at the heart of quantum-state engineering (QSE). Most of QSE experiments require initial states of well defined atomic spin (or total angular momentum F ), usually prepared in a stretched state, which is realized by putting most of (ideally all) atomic population into a Zeeman sublevel with extreme value of magnetic quantum number m [9]. Below we report how superpositions of specific Zeeman sublevels, or Zeeman coherences belonging to a given F are created in cold (∼100 µK) atomic samples and observed with high sensitivity using nonlinear Faraday rotation. In the experiment laser light both creates and detects the Zeeman coherences. The same detection technique can be applied to detect the presence of Zeeman coherences already introduced with other mechanisms. Furthermore, the time-dependent detection provides information on the temporal evolution of the superposition states.The described experiment shows the potential of NFR with cold atoms for precision magnetometry with prospective µG sensitivity, large dynamic range (zerofield to several G), and sub-mm spatial resolution in magnetic field mapping. Magnetic field sensing with cold atoms utilizing Larmor precession of alkali atoms in a magnetic field has been discussed in: MOT [10], Bose-Einstein condensate [11,12] and ...

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Observation of Larmor spin precession of laser-cooled Rb atoms via paramagnetic Faraday rotation

Cited by 42 publications

References 18 publications

Faraday spectroscopy of atoms confined in a dark optical trap

Faraday spectroscopy of atoms confined in a dark optical trap

Continuous Faraday measurement of spin precession without light shifts

Nonlinear Faraday rotation and detection of superposition states in cold atoms

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