A theory is developed for the optical pumping of alkali atoms with allowance for Zeeman and hyperfine structures and atomic motion in the model of instantaneous mixing between the Zeeman and ...hyperfine sublevels in an excited state. The appearance of the angular momentum in the
87
Rb and
133
Cs atoms that is opposite to the momentum of the photons pumping these atoms is studied. This effect is found to be most pronounced in the
D
2
line. The influence of the buffer gas pressure and the optical pumping intensity on the features of this effect is analyzed. The influence of the counterpolarization effect on the parameters of high-sensitivity quantum magnetometers is discussed.
The luminescence excitation spectra of the
D
1
resonance line of atoms K, Rb, and Cs in gas mixtures with CF
4
are found to contain satellite transitions, which correspond to the transition of an ...atom to the states (
n
– 1)
d
2
D
3/2,5/2
and (
n
+ 1)
s
2
S
1/2
, where
n
= 4, 5, and 6 for K, Rb, and Cs, respectively, with the simultaneous excitation of CF
4
molecule vibrations at the IR active mode frequency ν
3
with a quantum energy of 1283 cm
–1
. These satellite transitions are A(
ns
2
S
1/2
) + CF
4
(ν
3
= 0) +
h
ν → A((
n
– 1)
d
2
D
3/2,5/2
) + CF
4
(ν
3
= 1) and A(
ns
2
S
1/2
) + CF
4
(ν
3
= 0) +
h
ν → A((
n
+ 1)
s
2
S
1/2
) + CF
4
(ν
3
= 1), where A = K, Rb, and Cs. The appearance of an optical coupling between the upper and lower states of these asymptotically (at
→ ∞) forbidden transitions is shown to be caused by the interaction of the dipole moment of the ν
3
= 1 ↔ ν
3
= 0 vibrational transition in the CF
4
molecule with the dipole moments of the electronic transitions
np
2
P
1/2,3/2
↔ (
n
– 1)
d
2
D
3/2,5/2
and
np
2
P
1/2,3/2
↔ (
n
+ 1)
s
2
S
1/2
in an alkali metal atom; as a result of this interaction, the upper state of the satellite transition acquires admixtures of the A(
np
2
P
1/2,3/2
)CF
4
(ν
3
= 0) resonance states.
The principal limitations imposed by spin (or atomic) quantum projection noise on the sensitivity of optical quantum sensors on thermal atoms, which include frequency standards, magnetometers, and ...gyroscopes that use optical detection of electron paramagnetic resonance, have been theoretically and experimentally studied. The effect of increasing the rms amplitude of the projection noise in a magnetometric scheme under the influence of a strong optical pumping has been demonstrated. Its explanation has been proposed and experimentally confirmed: it has been shown that this effect is explained by the invariance of the integral power of projection noise in relation to the magnetic resonance linewidth in a wide range of pumping intensities An experimental study of the parameters of projection noise in a magnetometric quantum sensor has been conducted and recommendations for optimizing the sensor parameters have been given.
A variant of the scheme of a magnetometric sensor based on cesium atomic vapor is proposed and experimentally investigated. The sensor uses magnetic resonance excitation by modulated light of an ...hyperfine optical pumping that is transverse to the magnetic field. It is shown that, for a cell with a volume of 0.125 cm
3
, the variational sensitivity of such a scheme, estimated from the ratio of the steepness of the signal in the center of the magnetic resonance to the shot noise of the detecting radiation, reaches a level of <10 fT/Hz
1/2
in the frequency band width of the order of 850 Hz. The sensor, which does not emit radio frequency fields, is designed for use in magnetoencephalographic complexes. Possible ways to improve the performance of the scheme for detecting relatively fast (~4.2 kHz in a field of 0.1 mT) signals of the precession of proton magnetic moments in promising ultra-weak field tomography schemes are considered.
We analyze the polarization of the total angular momentum of alkali atoms in a gas cell with a buffer gas under pumping by monofrequency circularly polarized laser radiation. The mathematical model ...takes into account the motion of atoms and collisions preserving the nuclear spin under the chaotization of the angular momentum of the outer electron shell, total hyperfine structure, and the Zeeman structure. We analyze the stationary solution to equations for the density matrix of alkali atoms and the effect produced on them by the fraction of inelastic collision in which the quenching of atomic excitation takes place. We consider the contribution of various hyperfine states to the polarization of alkali atoms. The results are compared with the results of the model of instantaneous mixing of populations in the excited state.
We have performed a comparison of laser (LsOPM) and lamp (LpOPM) pumped cesium vapor magnetometers. Although the LsOPM operated 50% above its shot-noise limit we found an intrinsic sensitivity of 15 ...fT/radicHz and 25 fT/radicHz for the LsOPM and the LpOPM, respectively. Two modes of operation, viz. the phase-stabilized and the self-oscillating modes, were investigated and found to yield a similar performance. We have compared the performance of the LsOPM and the LpOPM directly by simultaneous measurements of field fluctuations of a 2-*mT magnetic field inside a multilayer magnetic shield and have used one of the magnetometers for an active field stabilization. In the stabilized mode we found a gradient instability of 25 fT within an integration time of 100 s, which represents an upper limit of the long-term stability of the magnetometers. Our research is motivated by the need for an improved control of magnetic fields and gradients in a planned neutron electric dipole experiment.
•Simultaneous excitation of colliding alkali atom and CF4 molecule by one photon.•CF4 provides fast population transfer between the resonance states of alkali atom.•CF4 is of interest as component of ...active mixtures of diode pumped alkali lasers.
The absorption and luminescence excitation spectra of gas phase mixtures of alkali metals atoms A (A = K, Rb, Cs) with carbon tetrafluoride molecules CF4 are studied in the region of transitions from the ground state A(2S1/2) to the lowest resonance states A(2P1/2, 3/2). It is shown that these transitions have intense satellites corresponding to the simultaneous vibrational excitation of the carbon tetrafluoride molecule, A(2S1/2) + CF4(v3=0) + hv → A(2P1/2, 3/2) + CF4(v3=1), where v3 is the IR active mode of CF4 with a vibrational quantum energy of 1281 cm–1. The satellites are relatively narrow bands (FWHM ~ 30 cm–1) slightly (< 10 cm–1) shifted to the red from the energies corresponding to the asymptotes A(2PJ) + CF4(v3=1), J=1/2, 3/2. The spectral width and position of the satellites indicate that these transitions occur at relatively large atom-molecule distances. In contrast to the majority of the studied before pair excitation processes in the gas phase, the intensity borrowing mechanism responsible for the observed satellite bands cannot be explained by the dipole-dipole interaction. Possible alternative mechanisms are discussed. It is also established that mixtures with CF4 are chemically stable including at elevated temperatures up to at least 200°C and their optical excitation results in resonance luminescence of alkali atoms. As compared to Ar, collisions with CF4 provides a higher rate of the population transfer between the A(2P1/2) and A(2P3/2) states. These results indicate that CF4 may be used as a component of the active medium of diode pumped alkali lasers.
Display omitted
—The possibility of using vertical-emitting lasers with intracavity contacts (IC-VCSEL) and a rhomboidal oxide current aperture for creating a non-zero magnetic field optically pumped atomic ...magnetometers (OPM) with a
133
Cs vapor cell for magnetoencephalographic (MEG) systems were demonstrated. Relative intensity noise (RIN) and polarization resolved RIN of the IC-VCSEL in the 895 nm range with different mirror losses (linewidth) in the frequency range from 1Hz to 100 kHz were experimentally investigated. Lasers with low mirror loss (narrow linewidth) have polarization resolved RIN comparable to amplitude noise. For IC-VCSEL with an output optical power of 0.8 mW and a linewidth of 55 MHz, the noise level measured is 148 dB/Hz in 1 Hz bandwidth at 40 kHz frequency. The ultimate sensitivity of OPM based on two-beam
M
Z
-scheme with studied VCSELs was estimated as ~11 fT/
.
The fundamental limitations for the basic metrological parameters of the nuclear magnetic resonance gyro (NMRG) are analyzed. The determinant factors limiting its sensitivity, such as atomic ...projection noise and light shot noise, are considered. Formulas are derived to estimate the ultimate sensitivity of the NMRG and study its dependence on the parameters of the sensitive element. The main causes of NMRG drifts and possible ways to improve its metrological characteristics are discussed.
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