Optically polarizedHe3

Abstract

This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.

Chip-scale atomic devices

“…249 A five-layer set of nested shields with volumes ranging from 2.5 cm 3 to 0.01 cm 3 were demonstrated. The shielding factor for the three outer-most layers was measured to be 6 Â 10 6 , and the shielding factor for all five layers together was calculated to be possibly as high as 10 11 . This high shielding factor is a result of the very strong scaling with shield dimension for multi-layer shields under the condition that the shield thickness remains constant.…”

“…10 Finally, nuclear spin coherence times of atoms in the vapor phase can be as high as several days. 11,12 The commercial atomic clock market today is dominated by two clock designs: vapor cell atomic clocks, discussed in detail below and usually based on Rb, and beam clocks based on Cs. Vapor cell clocks rely on an atomic vapor coexisting with a solid or liquid phase, all confined in a cell.…”

High-precision determination of the frequency-shift enhancement factor in Rb- Xe129

“…Almost six decades have passed since the first report of a hyperpolarized noble gas [1], but the field continues to grow and evolve, both in terms of the basic physics and the manifold applications. Nuclei of the stable spin- 1 2 isotopes, 3 He [2] and 129 Xe [3] may be polarized by spin-exchange optical pumping (SEOP) [4], a two-stage process of angular momentum transfer. The ground-state electron spins of an alkali-metal vapor are polarized by the absorption of circularly polarized resonant light at the D 1 transition (5S 1/2 → 5P 1/2 in Rb); subsequent collisions of the polarized alkali-metal atoms with noble gas atoms mediate an interatomic Fermi-contact interaction through which electron and nuclear spin is exchanged.…”

“…In Eqs. (1) and (2), [X], µ X , and K are the noble-gas number density, magnetic moment, and spin, respectively; h is Planck's constant, B 0 is the applied magnetic field, and κ AX > 0 is a dimensionless factor specific to each alkali-metal/noble-gas pair that parameterizes the enhancement of the noble-gas magnetic field sensed by the alkali-metal electrons. The enhanced field results from the quantum mechanical overlap of the electron wave function at the noble-gas nucleus, time-averaged over many collisions.…”

Transverse optical pumping of spin states

“…Second, any application that is restricted to a single laser direction can now use our scheme to control and fine tune the final direction of the pumped spins (longitudinal, transversal, or combination thereof). Such applications include remote magnetometry of mesospheric sodium spins [25,39], steady-state entanglement generation during pumping [18], optical pumping of metastable 3 He for medical imaging [40], and coherent manipulation of the internal spin state of cold atoms without associate heating [41].…”