Physical Review Letters

Faraday effect as a probe of hindered electronic precession in atoms

M. Kristensen, Martijn A. van Eijkelenborg, J. P. Woerdman

Published Apr 4, 1994• 6 citations

Abstract

We compare the Faraday spectrum with the dispersion spectrum near the ${\mathit{D}}_{2}$ line of Rb atoms immersed in a high density Xe buffer gas. We observe deviations from the standard Becquerel relation, which relates the Faraday effect of an atomic gas to its dispersion. The deviations are due to coupling of the Rb valence electron to the Xe environment. The Rb ${\mathit{D}}_{2}$ transition dipole moment becomes rotationally locked to the instantaneous collision axes at Xe densities of \ensuremath{\sim}${10}^{20}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$.

DOI: 10.1103/physrevlett.72.2155

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Onset of a collisional modification of the Faraday effect in a high-density atomic gas

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Physical Review Letters

Faraday effect as a probe of hindered electronic precession in atoms

M. Kristensen, Martijn A. van Eijkelenborg, J. P. Woerdman

Published Apr 4, 1994• 6 citations

Publisher

Abstract

We compare the Faraday spectrum with the dispersion spectrum near the

{\mathit{D}}_{2}

line of Rb atoms immersed in a high density Xe buffer gas. We observe deviations from the standard Becquerel relation, which relates the Faraday effect of an atomic gas to its dispersion. The deviations are due to coupling of the Rb valence electron to the Xe environment. The Rb

{\mathit{D}}_{2}

transition dipole moment becomes rotationally locked to the instantaneous collision axes at Xe densities of \ensuremath{\sim}

{10}^{20}

{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}

DOI: 10.1103/physrevlett.72.2155

Related papers

Onset of a collisional modification of the Faraday effect in a high-density atomic gas

M. Kristensen, F.J. Blok, Martijn A. van Eijkelenborg +2 more

We investigate, theoretically and experimentally, the onset of modified electronic precession due to quasimolecular behavior in dense atomic gases. The close connection between the angular coupling of collision pairs and a modification of the Faraday effect is pointed out. We have observed the onset of this quasimolecular modification of the atomic Faraday effect with high-resolution laser measurements of the absorption and Faraday spectra near the ${\mathit{D}}_{2}$ line of Rb atoms immersed in high-density buffer gases. The atomic Faraday effect itself is also affected by the presence of nuclear spin; this modifies the electronic precession through angular-momentum coupling. We describe how to separate the effect of nuclear spin from the effects due to quasimolecular behavior. In this way we establish the existence of angular coupling of the Rb valence electrons to neighboring buffer-gas atoms at densities above \ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{} ${10}^{19}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ in Xe buffer gas. In He buffer gas, quasimolecular modifications of the Faraday effect are approximately two times smaller than for Xe.We investigate, theoretically and experimentally, the onset of modified electronic precession due to quasimolecular behavior in dense atomic gases. The close connection between the angular coupling of collision pairs and a modification of the Faraday effect is pointed out. We have observed the onset of this quasimolecular modification of the atomic Faraday effect with high-resolution laser measurements of the absorption and Faraday spectra near the ${\mathit{D}}_{2}$ line of Rb atoms immersed in high-density buffer gases. The atomic Faraday effect itself is also affected by the presence of nuclear spin; this modifies the electronic precession through angular-momentum coupling. We describe how to separate the effect of nuclear spin from the effects due to quasimolecular behavior. In this way we establish the existence of angular coupling of the Rb valence electrons to neighboring buffer-gas atoms at densities above \ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ in Xe buffer gas. In He buffer gas, quasimolecular modifications of the Faraday effect are approximately two times smaller than for Xe.

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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 magic-zero wavelength at 790 nm between the fine-structure doublet of $^{87}\mathrm{Rb}$ 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 $\ensuremath{\mu}\mathrm{G}$ accuracy every 5 ms; or, equivalently, makes more than 200 successive measurements each at $10\phantom{\rule{0.16em}{0ex}}\mathrm{pT}/\sqrt{\mathrm{Hz}}$ sensitivity.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 magic-zero wavelength at 790 nm between the fine-structure doublet of $^{87}\mathrm{Rb}$ 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 $\ensuremath{\mu}\mathrm{G}$ accuracy every 5 ms; or, equivalently, makes more than 200 successive measurements each at $10\phantom{\rule{0.16em}{0ex}}\mathrm{pT}/\sqrt{\mathrm{Hz}}$ sensitivity.

arXiv:1705.10965Physical Review ADec 1, 201721 citations

We compare the Faraday spectrum with the dispersion spectrum near the

{\mathit{D}}_{2}

{\mathit{D}}_{2}

transition dipole moment becomes rotationally locked to the instantaneous collision axes at Xe densities of \ensuremath{\sim}

{10}^{20}

{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}

{\mathit{D}}_{2}

line of Rb atoms immersed in high-density buffer gases. The atomic Faraday effect itself is also affected by the presence of nuclear spin; this modifies the electronic precession through angular-momentum coupling. We describe how to separate the effect of nuclear spin from the effects due to quasimolecular behavior. In this way we establish the existence of angular coupling of the Rb valence electrons to neighboring buffer-gas atoms at densities above \ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}

{10}^{19}

${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ in Xe buffer gas. In He buffer gas, quasimolecular modifications of the Faraday effect are approximately two times smaller than for Xe.

We have measured the

{\mathit{D}}_{1}

and

{\mathit{D}}_{2}

Faraday spectrum and absorption spectrum of Rb atoms immersed in high-density Xe buffer gas in the range

{\mathit{n}}_{\mathrm{Xe}}

=0.8--4.5\ifmmode\times\else\texttimes\fi{}

{10}^{20}

${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. We find that the shape of the Faraday spectrum obeys the Becquerel relation over this whole density range; however the relative strength of the Faraday effect compared to absorption changes rather abruptly near

{\mathit{n}}_{\mathrm{Xe}}

=1\ifmmode\times\else\texttimes\fi{}

{10}^{20}

${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. This is ascribed to the onset of a many-body nature (overlapping collisions) of the Rb:Xe line broadening; the number of perturbers within the Weisskopf sphere is unity at

{\mathit{n}}_{\mathrm{Xe}}

\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}

{10}^{20}

${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. \textcopyright{} 1996 The American Physical Society.

^{87}\mathrm{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 $\ensuremath{\mu}\mathrm{G}$ accuracy every 5 ms; or, equivalently, makes more than 200 successive measurements each at

10\phantom{\rule{0.16em}{0ex}}\mathrm{pT}/\sqrt{\mathrm{Hz}}

sensitivity.