Suppression of Spin-Exchange Relaxation Using Pulsed Parametric Resonance

Korver, Anna; Wyllie, Robert; Lancor, Brian; Walker, Thad

doi:10.1103/physrevlett.111.043002

Cited by 37 publications

(22 citation statements)

References 19 publications

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“…The only limitation comes from the finite duration of the π pulses, t p , during which spin-exchange relaxation occurs. As shown in [28], the remaining relaxation rate is proportional to the duty cycle of the pulses t p /τ .…”

Section: Uses a Train Ofmentioning

confidence: 98%

He3−Xe129 Comagnetometery using
Limes
¹
,
Sheng
²
,
Romalis
³

2018
Phys. Rev. Lett.
126
2
81
0
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We describe a 3 He-129 Xe comagnetometer using 87 Rb atoms for noble-gas spin polarization and detection. We use a train of 87 Rb π pulses and σ + /σ − optical pumping to realize a finite-field Rb magnetometer with suppression of spin-exchange relaxation. We suppress frequency shifts from polarized Rb by measuring the 3 He and 129 Xe spin precession frequencies in the dark, while applying π pulses along two directions to depolarize Rb atoms. The plane of the π pulses is rotated to suppress the Bloch-Siegert shifts for the nuclear spins. We measure the ratio of 3 He to 129 Xe spin precession frequencies with sufficient absolute accuracy to resolve the Earth's rotation without changing the orientation of the comagnetometer. A frequency resolution of 7 nHz is achieved after integration for 8 hours without evidence of significant drift.PACS numbers: 32.30. Dx, 06.30.Gv, 39.90.+d Spin comagnetometers first introduced in [1] are used for several types of fundamental physics experiments, such as tests of Lorentz, CP and CPT symmetries [2][3][4][5] and searches for spin-dependent forces [6][7][8][9][10]. They also have practical applications as inertial rotation sensors [11][12][13][14][15][16]. When two different spin ensembles occupy the same volume they experience nearly the same average magnetic field [17]. The ratio of their spin precession frequencies f r = ω He /ω Xe can then be used to measure the inertial rotation rate Ω or a spin coupling beyond the Standard Model b:( 1) where B 0 is the bias field alongẑ and γ He , γ Xe are the gyromagnetic ratios for 3 He and 129 Xe, which are well known [18]. Since I = 1/2 nuclear spins are free from quadrupolar energy shifts [19], f r provides an absolute measure of non-magnetic spin interactions-this is particularly important in searches for spin-gravity coupling [20] (where the interaction is hard to modulate), and for use as a gyroscope.An alkali-metal magnetometer provides a natural way to detect nuclear-spin signals because Rb atoms are already used to polarize the nuclear spins by spin-exchange collisions; these collisions enhance the classical dipolar field from the nuclear magnetization by a factor κ 0 [21], which is about 5 for Rb-3 He [22] and 500 for Rb-Xe [23]. However, the presence of polarized Rb atoms also causes large noble-gas frequency shifts that affect the accuracy of Eq. (1). In the past, these frequency shifts have been avoided in 3 He-129 Xe comagnetometers by detecting a smaller dipolar field outside of an alkali-free cell using an RF coil [24] or a SQUID magnetometer [25].In this Letter we describe a new method for operating the 3 He-129 Xe comagnetometer using 87 Rb readout with high sensitivity and accuracy. We develop a 87 Rb magnetometer that can operate in a finite magnetic field of about 5 mG while suppressing Rb-Rb spin-exchange relaxation to increase the magnetometer sensitivity. It

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Section: Uses a Train Ofmentioning

confidence: 98%

He3−Xe129 Comagnetometery using
Limes
¹
,
Sheng
²
,
Romalis
³

2018
Phys. Rev. Lett.
126
2
81
0
View full text Add to dashboard Cite

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“…1. This bias magnetic field is applied as a sequence of short alkali 2π pulses, allowing the alkali atoms to be polarized perpendicular to the bias field [18]. By periodically reversing the alkali polarization direction at the noble gas resonance frequency, transverse nuclear polarization is resonantly generated by spin-exchange collisions.…”

mentioning

confidence: 99%

Synchronous Spin-Exchange Optical Pumping

et al. 2015

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We describe a new approach to precision NMR with hyperpolarized gases designed to mitigate NMR frequency shifts due to the alkali spin exchange field. The electronic spin polarization of optically pumped alkali atoms is square-wave modulated at the noble-gas NMR frequency and oriented transverse to the DC Fourier component of the NMR bias field. Noble gas NMR is driven by spin-exchange collisions with the oscillating electron spins. On resonance, the time-average torque from the oscillating spin-exchange field produced by the alkali spins is zero. Implementing the NMR bias field as a sequence of alkali 2π-pulses enables synchronization of the alkali and noble gas spins despite a 1000-fold discrepancy in gyromagnetic ratio. We demonstrate this method with Rb and Xe, and observe novel NMR broadening effects due to the transverse oscillating spin exchange field. When uncompensated, the spin-exchange field at high density broadens the NMR linewidth by an order of magnitude, with an even more dramatic suppression (up to 70x) of the phase shift between the precessing alkali and Xe polarizations. When we introduce a transverse compensation field, we are able to eliminate the spin-exchange broadening and restore the usual NMR phase sensitivity. The projected quantum-limited sensitivity is better than 1 nHz// √ Hz.The ability to produce highly magnetized noble gases via spin-exchange collisions with spin-polarized alkali atoms [1] has greatly impacted scientific studies of magnetic resonance imaging [2], high-energy nuclear physics with spin-polarized targets [3], and chemical physics [4]. Applications in precision measurements began with NMR gyros [5] and have continued with fundamental symmetry tests using multiple cell free induction decay [6], dual-species masers [7,8], selfcompensating co-magnetometers [9], NMR oscillators [10], and free spin-precession co-magnetometers [11][12][13][14].Some of these approaches [5, 9-11, 14] take advantage of enhanced NMR detection by the embedded alkali magnetometer. The alkali and noble-gas spin ensembles experience enhanced polarization sensitivity due to the Fermi-contact interaction during collisions between the two species. The effective Fermi-contact fields experienced by the two species arewhere S, K are the electron and nuclear spin operators, n S , n K the atomic densities, µ K the nuclear magnetic moment of the noble gas, µ B the Bohr magneton, and the atomic g-factor g ≈ 2. The frequency-shift enhancement factor κ [15,16] was recently measured to be 493 ± 31 [17] for RbXe. Thus the detected NMR field B SK is ∼500× larger for the embedded magnetometer than for any external sensor. This seemingly decisive advantage comes with the cost of similarly enhancing the B KS field due to the spin-polarized alkali atoms, 190 µG at 2n S S = 10 13 cm −3 . In typical longitudinally polarized NMR this field produces large frequency shifts of order 0.1 Hz. One approach for mitigating this effect is to compare two Xe isotopes [5,11], for which the enhancement factors are equal to about 0....

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“…As shown in Ref. [28], the remaining relaxation rate is proportional to the duty cycle of the pulses t p =τ.…”

mentioning

confidence: 77%

Spin Gyroscope is Ready to Look for New Physics

Kimball

2018

Physics

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We describe a 3 He-129 Xe comagnetometer using 87 Rb atoms for noble-gas spin polarization and detection. We use a train of 87 Rb π pulses and σ þ =σ − optical pumping to realize a finite-field Rb magnetometer with suppression of spin-exchange relaxation. We suppress frequency shifts from polarized Rb by measuring the 3 He and 129Xe spin precession frequencies in the dark, while applying π pulses along two directions to depolarize Rb atoms. The plane of the π pulses is rotated to suppress the Bloch-Siegert shifts for the nuclear spins. We measure the ratio of 3 He to 129 Xe spin precession frequencies with sufficient absolute accuracy to resolve Earth's rotation without changing the orientation of the comagnetometer. A frequency resolution of 7 nHz is achieved after integration for 8 h without evidence of significant drift. DOI: 10.1103/PhysRevLett.120.033401 Spin comagnetometers first introduced in Ref.[1] are used for several types of fundamental physics experiments, such as tests of Lorentz, CP, and CPT symmetries [2][3][4][5] and searches for spin-dependent forces [6][7][8][9][10]. They also have practical applications as inertial rotation sensors [11][12][13][14][15][16]. When two different spin ensembles occupy the same volume they experience nearly the same average magnetic field [17]. The ratio of their spin precession frequencies f r ¼ ω He =ω Xe can then be used to measure the inertial rotation rate Ω or a spin coupling beyond the standard model b:where B 0 is the bias field alongẑ and γ He , γ Xe are the gyromagnetic ratios for 3 He and 129 Xe, which are well known [18]. Since I ¼ 1=2 nuclear spins are free from quadrupolar energy shifts [19], f r provides an absolute measure of nonmagnetic spin interactions-this is particularly important in searches for spin-gravity coupling [20] (where the interaction is hard to modulate), and for use as a gyroscope. An alkali-metal magnetometer provides a natural way to detect nuclear-spin signals because Rb atoms are already used to polarize the nuclear spins by spin-exchange collisions; these collisions enhance the classical dipolar field from the nuclear magnetization by a factor κ 0 [21], which is about 5 for Rb- However, the presence of polarized Rb atoms also causes large noble-gas frequency shifts that affect the accuracy of Eq. (1). In the past, these frequency shifts have been avoided in 3 He-129 Xe comagnetometers by detecting a smaller dipolar field outside of an alkali-free cell using a rf coil [24] or a SQUID magnetometer [25].In this Letter we describe a new method for operating the 3 He- 129Xe comagnetometer using 87Rb readout with high sensitivity and accuracy. We develop a 87Rb magnetometer that can operate in a finite magnetic field of about 5 mG while suppressing Rb-Rb spin-exchange relaxation to increase the magnetometer sensitivity. It uses a train of 87

show abstract

Suppression of Spin-Exchange Relaxation Using Pulsed Parametric Resonance

Cited by 37 publications

References 19 publications

He3−Xe129 Comagnetometery using
Limes
¹
,
Sheng
²
,
Romalis
³

2018
Phys. Rev. Lett.
126
2
81
0
View full text Add to dashboard Cite

He3−Xe129 Comagnetometery using
Limes
¹
,
Sheng
²
,
Romalis
³

2018
Phys. Rev. Lett.
126
2
81
0
View full text Add to dashboard Cite

Synchronous Spin-Exchange Optical Pumping

Spin Gyroscope is Ready to Look for New Physics

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Suppression of Spin-Exchange Relaxation Using Pulsed Parametric Resonance

Cited by 37 publications

References 19 publications

He3−Xe129 Comagnetometery using Limes1, Sheng2, Romalis3 2018Phys. Rev. Lett.1262810View full textAdd to dashboardCite

He3−Xe129 Comagnetometery using Limes1, Sheng2, Romalis3 2018Phys. Rev. Lett.1262810View full textAdd to dashboardCite

Synchronous Spin-Exchange Optical Pumping

Spin Gyroscope is Ready to Look for New Physics

Contact Info

Product

Resources

About

He3−Xe129 Comagnetometery using
Limes
¹
,
Sheng
²
,
Romalis
³

2018
Phys. Rev. Lett.
126
2
81
0
View full text Add to dashboard Cite

He3−Xe129 Comagnetometery using
Limes
¹
,
Sheng
²
,
Romalis
³

2018
Phys. Rev. Lett.
126
2
81
0
View full text Add to dashboard Cite