Relaxation of Optically Pumped Rb Atoms on Paraffin-Coated Walls

Bouchiat, Marie-Anne; Brossel, J.

doi:10.1103/physrev.147.41

Cited by 326 publications

(226 citation statements)

References 12 publications

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“…Among such coatings, paraffin and other materials with long chains of hydrocarbons were found to work well with alkali metals [22]. In a seminal study [23] Bouchiat and Brossel demonstrated that spin relaxation on paraffin is caused by two effects of comparable size, magnetic dipolar interaction and spin-rotation coupling. Magnetic dipolar relaxation is dominated by interaction between the magnetic moment of the electron and magnetic moments of protons in the coating.…”

Section: General Features and Limits Of Sensitivity Of Optical Mamentioning

confidence: 99%

Optical magnetometry

2007

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Some of the most sensitive methods of measuring magnetic fields utilize interactions of resonant light with atomic vapor. Recent developments in this vibrant field are improving magnetometers in many traditional areas such as measurement of geomagnetic anomalies and magnetic fields in space, and are opening the door to new ones, including, dynamical measurements of bio-magnetic fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance imaging (MRI), inertialrotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of Nature.

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Section: General Features and Limits Of Sensitivity Of Optical Mamentioning

confidence: 99%

Optical magnetometry

2007

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confidence: 99%

“…The cell walls are coated with octadecyltrichlorosilane (OTS) to reduce surface spin relaxation of K atoms. OTS molecules (CH 3 -(CH 2 ) 17 -Si-Cl 3 ) attach to glass through a silanization reaction and ideally expose alkali atoms only to a surface of long hydrocarbon chains, known to reduce wall relaxation due to their low polarizability [24]. We have used the coating procedure described in [25] and obtained K longitudinal spin relaxation time T 1 up to 145 msec, corresponding to 2100 collisions with the walls before depolarization, although the relaxation times were not entirely consistent and other cells coated in the same batch had T 1 of 1.6 ms, 20 ms, and 61 ms.…”

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Synchronous optical pumping of quantum revival beats for atomic magnetometry

2007

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We observe quantum beats with periodic revivals due to non-linear spacing of Zeeman levels in the ground state of potassium atoms and demonstrate their synchronous optical pumping by double modulation of the pumping light at the Larmor frequency and the revival frequency. We show that synchronous pumping increases the degree of spin polarization by a factor of 4. As a practical example, we explore the application of this double-modulation technique to atomic magnetometers operating in the geomagnetic field range and find that it can increase the sensitivity and reduce magnetic field orientation-dependent measurement errors endemic to alkali-metal magnetometers.PACS numbers: 07.55. Ge, 42.50.Md, 32.30.Dx, 32.80.Bx Periodic revival of quantum beats is a general phenomenon that occurs in multi-level systems with nonlinear energy level spacing [1,2] and has been observed in diverse systems, from one-atom masers [3] and Rydberg states in atoms [4] to molecular vibrational [5] and rotational [6] states. Recently molecular rotational revivals attracted significant attention because of the possibility of using them for alignment of molecules with ultrashort laser pulses [7,8,9,10]. It has been proposed that periodic laser pulses could be used to increase the degree of molecular alignment and maintain it indefinitely [11,12,13,14]. An increase of molecular alignment using two pulses has been demonstrated in [15].Here we show experimentally that appropriately synchronized train of laser pulses can increase in the degree of spin orientation and maintain it indefinitely by synchronously pumping quantum revivals in the groundstate Zeeman levels of an alkali-metal atom. Periodic revivals of quantum beats in Zeeman levels of alkalimetal atoms occur naturally due to non-linear Breit-Rabi mixing [16] and have been modeled in [17]. We observe quantum revivals in K atoms and demonstrate their synchronous pumping by double modulation of the pump laser at both the Larmor and the revival frequencies. We find that it creates a coherently oscillating superposition state with a spin polarization a factor of 4 higher than can be obtained without double modulation for the same average laser power. We also model the effects in other alkali atoms and find that the amount of polarization enhancement increases for systems with a larger number of quantum states.Because the revivals occur in geomagnetic field range of about 0.5 G, our experiments are also directly applicable to optically-pumped alkali-metal magnetometers, which are used in many applications, from archaeology [18] and mineral exploration [19] to searches for a CPviolating electric dipole moment [20]. As was recently discussed in [21,22], Breit-Rabi mixing of Zeeman levels decreases magnetometer sensitivity by splitting the Zeeman resonance into many separate lines. We show that synchronous pumping of quantum revivals largely recovers the signal loss. In addition, we demonstrate that it generates a symmetric resonance lineshape, reducing a systematic effect endemic to most alk...

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“…The measured intrinsic ground-state relaxation rate of about 2 Hz is consistent with estimated relaxation due to spin-exchange collisions and the exchange of atoms between the volume of the vapor cell and the stem. This is evidence of the high quality of the coating and a direct illustration of the remarkable properties of paraffin as the coating material [17,18]: it takes on the order of 10 4 collisions of a polarized atom with the paraffin-coated wall to induce relaxation. We have also measured the frequency shift and linewidth of the hyperfine 0-0 clock transition.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear magneto-optical rotation and Zeeman and hyperfine relaxation of potassium atoms in a paraffin-coated cell

et al. 2006

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Nonlinear magneto-optical Faraday rotation (NMOR) on the potassium D1 and D2 lines was used to study Zeeman relaxation rates in an antirelaxation paraffin-coated 3-cm diameter potassium vapor cell. Intrinsic Zeeman relaxation rates of γ NM OR /2π = 2.0(6) Hz were observed. The relatively small hyperfine intervals in potassium lead to significant differences in NMOR in potassium compared to rubidium and cesium. Using laser optical pumping, widths and frequency shifts were also determined for transitions between ground-state hyperfine sublevels of 39 K atoms contained in the same paraffincoated cell. The intrinsic hyperfine relaxation rate of γ hf expt /2π = 10.6(7) Hz and a shift of −9.1(2) Hz were observed. These results show that adiabatic relaxation gives only a small contribution to the overall hyperfine relaxation in the case of potassium, and the relaxation is dominated by other mechanisms similar to those observed in previous studies with rubidium.

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Relaxation of Optically Pumped Rb Atoms on Paraffin-Coated Walls

Cited by 326 publications

References 12 publications

Optical magnetometry

Optical magnetometry

Synchronous optical pumping of quantum revival beats for atomic magnetometry

Nonlinear magneto-optical rotation and Zeeman and hyperfine relaxation of potassium atoms in a paraffin-coated cell

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