劉強(qiáng)++卓艷男++黃強(qiáng)++張軍海+孫偉民+

文章編號(hào)： 10055630(2014)02015204

收稿日期： 20131008

摘要： 全光銫(Cs)原子磁力儀是一種高靈敏度弱磁檢測(cè)儀,核心器件Cs原子氣室的工作溫度直接決定了原子磁力儀的靈敏度。實(shí)驗(yàn)系統(tǒng)中采用頻率鎖定在Cs原子D1線F=3→F′=4共振線的圓偏振光極化Cs原子,檢測(cè)光采用頻率鎖定在Cs原子D2線F=4→F′=5共振線的線偏振光,檢測(cè)介質(zhì)的圓二向色性。實(shí)驗(yàn)發(fā)現(xiàn),隨著Cs原子氣室工作溫度的升高,磁力儀輸出信號(hào)幅度先增加然后逐漸衰減,而磁力儀的線寬近似線性增加。實(shí)驗(yàn)測(cè)試了溫度由25 ℃升高至45 ℃時(shí)的磁力儀輸出信號(hào),結(jié)果表明:當(dāng)溫度為37.6 ℃時(shí),原子磁力儀達(dá)到最佳靈敏度。

關(guān)鍵詞： 原子磁力儀; 工作溫度; 原子氣室; 圓二向色性

中圖分類號(hào)： O 433.5文獻(xiàn)標(biāo)志碼： Adoi： 10.3969/j.issn.10055630.2014.02.013

Temperature dependence of all optical Cs atomic magnetometer

LIU Qiang1, ZHUO Yannan1, HUANG Qiang2, ZHANG Junhai2, SUN Weimin2

(1.College of Electronic Science, Northeast Petroleum University, Daqing 163318, China;

2.College of Science, Harbin Engineering University, Harbin 150001, China)

Abstract： All optical atomic magnetometer with high sensitivity is an important device to detect weak magnetic field. The sensitivity of the atomic magnetometer will be influenced by the operating temperature of Cs vapor cell. As the frequency of circularly polarized pump light and the linearly polarized probe light are locked to Cs D1 transition F=3→F′=4 and Cs D2 transition F=4→F′=5 respectively, linearly polarized probe light will rotate a small angle due to circular dichroic medium. With the increase of the operating temperature of Cs vapor cell, the output peak signal will increase first and then decrease, but the bandwidth has been increasing. The output signal of magnetometer was measured as the operating temperature varied from 25 ℃ to 45 ℃. The result shows that 37.6 ℃ is the optimal temperature to achieve the highest sensitivity.

Key words： atomic magnetometer; operating temperature; atomic vapor cell; circular dichroism

引言磁場(chǎng)測(cè)量方法種類繁多［1］,而原子磁力儀是近年出現(xiàn)的一種高靈敏度弱磁場(chǎng)檢測(cè)技術(shù),磁測(cè)量靈敏度已經(jīng)優(yōu)于超導(dǎo)磁力儀達(dá)到0.16fT/Hz1/2 ［2］,并且這種磁力儀結(jié)構(gòu)簡(jiǎn)單,更易于小型化使其成為近年研究的熱點(diǎn)。目前,已經(jīng)采用原子磁力儀在實(shí)驗(yàn)室條件下進(jìn)行爆炸危險(xiǎn)物品檢測(cè),醫(yī)學(xué)領(lǐng)域的心磁、腦磁測(cè)量等相關(guān)領(lǐng)域的前期研究工作,同時(shí)還用于研究物理學(xué)中的基本對(duì)稱性［35］。原子磁力儀的基本原理是利用線偏振光檢測(cè)被極化的原子在磁場(chǎng)中的拉莫進(jìn)動(dòng)頻率［6］。參與作用的原子數(shù)對(duì)原子磁力儀的靈敏度通常起著決定性作用,基于無自旋互換弛豫效應(yīng)的原子磁力儀通常將原子氣室加熱至100 ℃以上來消除自旋互換碰撞弛豫［78］;而利用非線性磁光旋轉(zhuǎn)效應(yīng)的原子磁力儀卻通常將原子氣室置于常溫環(huán)境下［9］;基于相干布居囚禁技術(shù)的87Rb原子磁力儀中原子氣室的工作溫度為70 ℃［10］。由此可見,為達(dá)到極限磁測(cè)量靈敏度,基于不同原理的原子磁力儀均存在最佳的工作溫度值。本文研究了一種高靈敏度全光Cs原子磁力儀,在Cs原子氣室內(nèi)充入13 332.2 Pa的He緩沖氣體。將泵浦光頻率鎖定在Cs原子D1線F=3→F′=4共振線,檢測(cè)光頻率鎖定在Cs原子D2線F=4→F′=5共振線,測(cè)量了Cs原子氣室工作溫度由25 ℃升高至45 ℃時(shí)的磁力儀輸出信號(hào),通過對(duì)實(shí)驗(yàn)結(jié)果進(jìn)行分析發(fā)現(xiàn),當(dāng)Cs原子氣室工作溫度為37.6 ℃時(shí),原子磁力儀達(dá)到最佳靈敏度。圖1原子磁力儀原理圖

Fig.1Principle of atomic magnetometer1基本原理全光Cs原子磁力儀的工作過程可分成三部分［11］,如圖1所示:(1)圓偏振泵浦光極化Cs原子,極化方向沿泵浦光的傳播方向;(2)被極化的原子繞著磁場(chǎng)的方向作拉莫進(jìn)動(dòng);(3)線偏振光檢測(cè)被極化的原子在檢測(cè)光方向上的投影,偏振面產(chǎn)生旋轉(zhuǎn)。檢測(cè)光偏振面旋轉(zhuǎn)角θ為［12］θ∝lcrenfDPxL(ν)(1)其中:l為泵浦光與檢測(cè)光交叉區(qū)長(zhǎng)度,c為光速,re為經(jīng)典電子半徑,n為粒子數(shù)密度,fD為振子強(qiáng)度,Px為原子極化在檢測(cè)光方向的投影,L(ν)為洛倫茲線型。光學(xué)儀器第36卷

第2期劉強(qiáng)，等：全光Cs原子磁力儀的溫度特性研究

原子磁力儀的靈敏度可表示為δB=ΔBS/N(2)其中:ΔB為原子磁力儀信號(hào)的線寬,S/N為偏振面旋轉(zhuǎn)角檢測(cè)的信號(hào)與噪聲之比。提高原子磁力儀的靈敏度的直接方法是減小磁力儀線寬,同時(shí)增大系統(tǒng)信噪比。由式(1)可知,提高Cs原子氣室工作溫度可使粒子數(shù)密度n顯著增加,輸出信噪比增大。然而Cs原子粒子數(shù)增加會(huì)導(dǎo)致自旋破壞碰撞和自旋互換碰撞幾率的增大,使原子磁力儀特性曲線的線寬增加。因此,由式（2）可知存在最佳的工作溫度,使磁力儀靈敏度達(dá)到最優(yōu)值。圖2原子磁力儀實(shí)驗(yàn)原理圖

Fig.2Experimental schematic diagram of atomic magnetometer2實(shí)驗(yàn)裝置全光Cs原子磁力儀實(shí)驗(yàn)系統(tǒng)如圖2所示。直徑為30 mm的球型Cs原子氣室置于三層磁屏蔽筒中,氣室內(nèi)充入13 332.2 Pa的He緩沖氣體,亥姆霍茲線圈在y方向產(chǎn)生待測(cè)磁場(chǎng)。泵浦光選用輸出波長(zhǎng)為894.6 nm的外腔半導(dǎo)體激光器,采用飽和吸收譜技術(shù)可將頻率鎖定在Cs原子D1線的F=3→F′=4超精細(xì)共振線處,經(jīng)準(zhǔn)直擴(kuò)束后采用電光幅度調(diào)制器(EOAM)對(duì)光強(qiáng)進(jìn)行方波調(diào)制。被調(diào)制的泵浦光進(jìn)入磁屏蔽筒后,經(jīng)偏振片和λ/4波帶片將其變成圓偏振光極化Cs原子。檢測(cè)光選用波長(zhǎng)為852.3 nm的外腔半導(dǎo)體激光器,利用飽和吸收譜將激光器頻率鎖定在Cs原子D2線F=4→F′=5共振線處,經(jīng)偏振片后變成線偏振光通過Cs原子氣室檢測(cè)介質(zhì)的圓二向色性,出射后由λ/4和PBS組成的光學(xué)系統(tǒng)進(jìn)行檢測(cè),經(jīng)光電轉(zhuǎn)換、放大、做差、濾波后送入鎖相放大器和示波器,實(shí)現(xiàn)磁場(chǎng)測(cè)量,同時(shí)估算原子磁力儀的靈敏度。3實(shí)驗(yàn)結(jié)果與分析將Cs原子氣室置于亥姆霍茲線圈中心,產(chǎn)生100nT待測(cè)磁場(chǎng),泵浦光強(qiáng)Ip=6 mW/cm2,頻率鎖定在Cs原子D1線F=3→F′=4共振線,檢測(cè)光強(qiáng)Id=0.2 mW/cm2,頻率鎖定在Cs原子D2線F=4→F′=5共振線,Cs原子氣室工作溫度為37.6 ℃,測(cè)量到的原子磁力儀響應(yīng)特性曲線如圖3所示。橫軸表示泵浦光強(qiáng)的調(diào)制頻率,縱軸表示鎖相放大器的同相輸出信號(hào),其幅值為線偏振檢測(cè)光偏振面的旋轉(zhuǎn)角度。當(dāng)泵浦光的調(diào)制頻率與被極化原子繞磁場(chǎng)的拉莫進(jìn)動(dòng)頻率相等時(shí),檢測(cè)光偏振面旋轉(zhuǎn)角出現(xiàn)極大值,即同相輸出信號(hào)幅值達(dá)到峰值,此時(shí)峰值對(duì)應(yīng)的橫坐標(biāo)頻率為350 Hz。根據(jù)拉莫進(jìn)動(dòng)頻率與磁場(chǎng)的關(guān)系 ω=γB(對(duì)于Cs原子γ=3.5 Hz/nT)可知,Cs原子氣室所在位置的磁場(chǎng)值為100 nT,從而實(shí)現(xiàn)磁場(chǎng)測(cè)量。為分析溫度對(duì)原子磁力儀靈敏度的影響,實(shí)驗(yàn)中首先固定泵浦光強(qiáng)和檢測(cè)光強(qiáng),測(cè)量了原子磁力儀響應(yīng)特性曲線的峰值隨溫度的變化關(guān)系,如圖4中離散點(diǎn)所示。隨著溫度的增加,Cs原子粒子數(shù)密度增加導(dǎo)致磁力儀輸出信號(hào)的增大,在40 ℃左右達(dá)到極值,然后逐漸減小。產(chǎn)生這種現(xiàn)象的原因是:(1)隨著溫度的升高,Cs原子將由光學(xué)薄介質(zhì)向光學(xué)厚介質(zhì)轉(zhuǎn)變,而泵浦光與檢測(cè)光的交叉區(qū)域并未覆蓋整個(gè)氣室(如圖2所示),導(dǎo)致泵浦光在與檢測(cè)光交叉前會(huì)被Cs原子強(qiáng)烈吸收,有效泵浦光強(qiáng)減小。(2)與泵浦光類似,處于Cs原子共振線的檢測(cè)光也會(huì)在與泵浦光交叉前后的區(qū)域中被Cs原子吸收,檢測(cè)光強(qiáng)通常都比較小,如果這種吸收較強(qiáng)將直接影響輸出信號(hào)的幅度,等價(jià)于在公式(1)的基礎(chǔ)上乘吸收項(xiàng)exp(-nσl)。其中,n為粒子數(shù)密度,σ為吸收截面,l為泵浦光與檢測(cè)光的非交叉區(qū)長(zhǎng)度。理論計(jì)算結(jié)果如圖4實(shí)線所示,與實(shí)驗(yàn)結(jié)果基本一致。

圖3原子磁力儀響應(yīng)特性曲線

Fig.3Output signal of atomic

magnetometer圖4不同溫度下的輸出信號(hào)幅度

Fig.4Output amplitude of atomic

magnetometer at different temperature

為了估算磁力儀獲得最佳靈敏度時(shí)的Cs原子氣室工作溫度,除了考慮磁力儀特性曲線的峰值幅度外,還需考慮曲線線寬。為此,在不同的溫度下,測(cè)量得到的磁力儀特性曲線的峰值如圖5所示,隨著泵浦光強(qiáng)的增加輸出信號(hào)峰值先迅速增加然后逐漸趨緩,說明泵浦光強(qiáng)逐漸達(dá)到原子極化所需的飽和光強(qiáng)。各溫度下曲線峰值隨泵浦光強(qiáng)的變化具有相同的變化趨勢(shì),說明非交叉區(qū)Cs原子對(duì)泵浦光的吸收可通過增加泵浦光強(qiáng)進(jìn)行補(bǔ)償。圖6給出不同溫度下,磁力儀特性曲線的線寬隨泵浦光強(qiáng)的變化關(guān)系。在某一固定溫度下,泵浦光強(qiáng)的增加將導(dǎo)致曲線線寬非線性增加。然而,當(dāng)泵浦光強(qiáng)固定的條件下,隨著溫度的升高,線寬將近似線性增加,如圖7所示,在此溫度范圍內(nèi),擬合函數(shù)為ΔB=0.6T+13.5。由此可見,溫度的變化不僅影響曲線峰值,同時(shí)影響曲線線寬。忽略Cs原子氣室工作溫度的變化導(dǎo)致的磁力儀噪聲,將此式與圖4的仿真結(jié)果帶入式(2),計(jì)算結(jié)果如圖8所示,可知Cs原子氣室的最佳工作溫度為37.6 ℃。

圖5不同溫度下響應(yīng)特性曲線峰值與泵浦光強(qiáng)的關(guān)系

Fig.5Dependence of amplitude on pumping

intensity at different temperature圖6不同溫度下泵浦光強(qiáng)與線寬的關(guān)系

Fig.6Dependence of bandwidth on pumping

intensity at different temperature

圖7不同溫度下的曲線線寬

Fig.7Bandwidth of inphase signal at

different temperature圖8不同溫度下原子磁力儀的相對(duì)靈敏度

Fig.8The relative sensitivity of atomic

magnetometer at different temperature

4結(jié)論本文介紹了一種高靈敏度全光Cs原子磁力儀,指出Cs原子氣室的工作溫度直接決定了原子磁力儀的靈敏度。當(dāng)泵浦光頻率鎖定在Cs原子D1線F=3→F′=4共振線,檢測(cè)光頻率鎖定在Cs原子D2線F=4→F′=5共振線時(shí),分別測(cè)量了Cs原子氣室工作溫度對(duì)輸出信號(hào)幅度和線寬的影響。發(fā)現(xiàn)隨著Cs原子氣室工作溫度的升高,磁力儀輸出信號(hào)幅度先增加然后逐漸衰減,而磁力儀的線寬近似線性增加。分析結(jié)果表明,當(dāng)Cs原子氣室的工作溫度為37.6 ℃時(shí),原子磁力儀可獲得最佳靈敏度。這項(xiàng)工作對(duì)進(jìn)一步優(yōu)化磁力儀結(jié)構(gòu),提高測(cè)磁靈敏度具有重要意義。參考文獻(xiàn)：

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［8］SHAH V,ROMALIS M V.Spinexchange relaxationfree magnetometry using elliptically polarized light［J］.Physical Review A,2009,80(1):134161134166.

［9］HOVDE C,PATTON B,CORSINI E,et al.Sensitive optical atomic magnetometer based on nonlinear magnetooptical rotation［C］∥Conference on Unattended Ground,Sea,and Air Sensor Technologies and Applications XII.Orlando:SPIE,2010,7693,769313176931310.

［10］LIU G B,GU S H.Experimental study of the CPT magnetometer worked on atomic energy level modulation［J］.Journal of Physics B:Atomic,Molecular and Optical Physics,2010,43(3):350041350044.

［11］BUDKER D,ROMALIS M V.Optical magnetometry［J］.Nature Physical,2007,3(4):227234.

［12］Seltzer S J.Developments in alkalimetal atomic magnetometry［D］.Princeton:Princeton University,2008.第36卷第2期2014年4月光學(xué)儀器OPTICAL INSTRUMENTSVol.36, No.2April, 2014

［3］XIA H,BENAMAR BARANGA A,HOFFMAN D,et al.Magnetoencephalography with an atomic magnetometer［J］.Applied Physics Letters,2006,89(21):21110412111043.

［4］LEE S K,SAUER K L,SELTZER S J,et al.Subfemtotesla radiofrequency atomic magnetometer for detection of nuclear quadrupole resonance［J］.Applied Physics Letters,2006,89(21):21410612141063.

［5］BROWN J M,SMULLIN S J,KORNACK T W,et al.New limit on Lorentz and CPTViolating neutron spin interactions［J］.Physical Review Letters,2010,105(15):15160411516044.

［6］KOMINIS I K,KORNACK T W,ALLRED J C,et al.A subfemtotesla multichannel atomic magnetometer［J］.Nature,2003,422(6932):596599.

［7］SHAH V,VASILAKIS G,ROMALIS M V.High bandwidth atomic magnetometery with continuous quantum nondemolition measurements［J］.Physical Review Letters,2010,104(1):136011136014.

［8］SHAH V,ROMALIS M V.Spinexchange relaxationfree magnetometry using elliptically polarized light［J］.Physical Review A,2009,80(1):134161134166.

［9］HOVDE C,PATTON B,CORSINI E,et al.Sensitive optical atomic magnetometer based on nonlinear magnetooptical rotation［C］∥Conference on Unattended Ground,Sea,and Air Sensor Technologies and Applications XII.Orlando:SPIE,2010,7693,769313176931310.

［10］LIU G B,GU S H.Experimental study of the CPT magnetometer worked on atomic energy level modulation［J］.Journal of Physics B:Atomic,Molecular and Optical Physics,2010,43(3):350041350044.

［11］BUDKER D,ROMALIS M V.Optical magnetometry［J］.Nature Physical,2007,3(4):227234.

［12］Seltzer S J.Developments in alkalimetal atomic magnetometry［D］.Princeton:Princeton University,2008.

［3］XIA H,BENAMAR BARANGA A,HOFFMAN D,et al.Magnetoencephalography with an atomic magnetometer［J］.Applied Physics Letters,2006,89(21):21110412111043.

［4］LEE S K,SAUER K L,SELTZER S J,et al.Subfemtotesla radiofrequency atomic magnetometer for detection of nuclear quadrupole resonance［J］.Applied Physics Letters,2006,89(21):21410612141063.

［5］BROWN J M,SMULLIN S J,KORNACK T W,et al.New limit on Lorentz and CPTViolating neutron spin interactions［J］.Physical Review Letters,2010,105(15):15160411516044.

［6］KOMINIS I K,KORNACK T W,ALLRED J C,et al.A subfemtotesla multichannel atomic magnetometer［J］.Nature,2003,422(6932):596599.

［7］SHAH V,VASILAKIS G,ROMALIS M V.High bandwidth atomic magnetometery with continuous quantum nondemolition measurements［J］.Physical Review Letters,2010,104(1):136011136014.

［8］SHAH V,ROMALIS M V.Spinexchange relaxationfree magnetometry using elliptically polarized light［J］.Physical Review A,2009,80(1):134161134166.

［9］HOVDE C,PATTON B,CORSINI E,et al.Sensitive optical atomic magnetometer based on nonlinear magnetooptical rotation［C］∥Conference on Unattended Ground,Sea,and Air Sensor Technologies and Applications XII.Orlando:SPIE,2010,7693,769313176931310.

［10］LIU G B,GU S H.Experimental study of the CPT magnetometer worked on atomic energy level modulation［J］.Journal of Physics B:Atomic,Molecular and Optical Physics,2010,43(3):350041350044.

［11］BUDKER D,ROMALIS M V.Optical magnetometry［J］.Nature Physical,2007,3(4):227234.

［12］Seltzer S J.Developments in alkalimetal atomic magnetometry［D］.Princeton:Princeton University,2008.第36卷第2期2014年4月光學(xué)儀器OPTICAL INSTRUMENTSVol.36, No.2April, 2014

［3］XIA H,BENAMAR BARANGA A,HOFFMAN D,et al.Magnetoencephalography with an atomic magnetometer［J］.Applied Physics Letters,2006,89(21):21110412111043.

［4］LEE S K,SAUER K L,SELTZER S J,et al.Subfemtotesla radiofrequency atomic magnetometer for detection of nuclear quadrupole resonance［J］.Applied Physics Letters,2006,89(21):21410612141063.

［5］BROWN J M,SMULLIN S J,KORNACK T W,et al.New limit on Lorentz and CPTViolating neutron spin interactions［J］.Physical Review Letters,2010,105(15):15160411516044.

［6］KOMINIS I K,KORNACK T W,ALLRED J C,et al.A subfemtotesla multichannel atomic magnetometer［J］.Nature,2003,422(6932):596599.

［7］SHAH V,VASILAKIS G,ROMALIS M V.High bandwidth atomic magnetometery with continuous quantum nondemolition measurements［J］.Physical Review Letters,2010,104(1):136011136014.

［8］SHAH V,ROMALIS M V.Spinexchange relaxationfree magnetometry using elliptically polarized light［J］.Physical Review A,2009,80(1):134161134166.

［9］HOVDE C,PATTON B,CORSINI E,et al.Sensitive optical atomic magnetometer based on nonlinear magnetooptical rotation［C］∥Conference on Unattended Ground,Sea,and Air Sensor Technologies and Applications XII.Orlando:SPIE,2010,7693,769313176931310.

［10］LIU G B,GU S H.Experimental study of the CPT magnetometer worked on atomic energy level modulation［J］.Journal of Physics B:Atomic,Molecular and Optical Physics,2010,43(3):350041350044.

［11］BUDKER D,ROMALIS M V.Optical magnetometry［J］.Nature Physical,2007,3(4):227234.

［12］Seltzer S J.Developments in alkalimetal atomic magnetometry［D］.Princeton:Princeton University,2008.

［3］XIA H,BENAMAR BARANGA A,HOFFMAN D,et al.Magnetoencephalography with an atomic magnetometer［J］.Applied Physics Letters,2006,89(21):21110412111043.

［4］LEE S K,SAUER K L,SELTZER S J,et al.Subfemtotesla radiofrequency atomic magnetometer for detection of nuclear quadrupole resonance［J］.Applied Physics Letters,2006,89(21):21410612141063.

［5］BROWN J M,SMULLIN S J,KORNACK T W,et al.New limit on Lorentz and CPTViolating neutron spin interactions［J］.Physical Review Letters,2010,105(15):15160411516044.

［6］KOMINIS I K,KORNACK T W,ALLRED J C,et al.A subfemtotesla multichannel atomic magnetometer［J］.Nature,2003,422(6932):596599.

［7］SHAH V,VASILAKIS G,ROMALIS M V.High bandwidth atomic magnetometery with continuous quantum nondemolition measurements［J］.Physical Review Letters,2010,104(1):136011136014.

［8］SHAH V,ROMALIS M V.Spinexchange relaxationfree magnetometry using elliptically polarized light［J］.Physical Review A,2009,80(1):134161134166.

［9］HOVDE C,PATTON B,CORSINI E,et al.Sensitive optical atomic magnetometer based on nonlinear magnetooptical rotation［C］∥Conference on Unattended Ground,Sea,and Air Sensor Technologies and Applications XII.Orlando:SPIE,2010,7693,769313176931310.

［10］LIU G B,GU S H.Experimental study of the CPT magnetometer worked on atomic energy level modulation［J］.Journal of Physics B:Atomic,Molecular and Optical Physics,2010,43(3):350041350044.

［11］BUDKER D,ROMALIS M V.Optical magnetometry［J］.Nature Physical,2007,3(4):227234.

［12］Seltzer S J.Developments in alkalimetal atomic magnetometry［D］.Princeton:Princeton University,2008.第36卷第2期2014年4月光學(xué)儀器OPTICAL INSTRUMENTSVol.36, No.2April, 2014

［3］XIA H,BENAMAR BARANGA A,HOFFMAN D,et al.Magnetoencephalography with an atomic magnetometer［J］.Applied Physics Letters,2006,89(21):21110412111043.

［4］LEE S K,SAUER K L,SELTZER S J,et al.Subfemtotesla radiofrequency atomic magnetometer for detection of nuclear quadrupole resonance［J］.Applied Physics Letters,2006,89(21):21410612141063.

［5］BROWN J M,SMULLIN S J,KORNACK T W,et al.New limit on Lorentz and CPTViolating neutron spin interactions［J］.Physical Review Letters,2010,105(15):15160411516044.

［6］KOMINIS I K,KORNACK T W,ALLRED J C,et al.A subfemtotesla multichannel atomic magnetometer［J］.Nature,2003,422(6932):596599.

［7］SHAH V,VASILAKIS G,ROMALIS M V.High bandwidth atomic magnetometery with continuous quantum nondemolition measurements［J］.Physical Review Letters,2010,104(1):136011136014.

［8］SHAH V,ROMALIS M V.Spinexchange relaxationfree magnetometry using elliptically polarized light［J］.Physical Review A,2009,80(1):134161134166.

［9］HOVDE C,PATTON B,CORSINI E,et al.Sensitive optical atomic magnetometer based on nonlinear magnetooptical rotation［C］∥Conference on Unattended Ground,Sea,and Air Sensor Technologies and Applications XII.Orlando:SPIE,2010,7693,769313176931310.

［10］LIU G B,GU S H.Experimental study of the CPT magnetometer worked on atomic energy level modulation［J］.Journal of Physics B:Atomic,Molecular and Optical Physics,2010,43(3):350041350044.

［11］BUDKER D,ROMALIS M V.Optical magnetometry［J］.Nature Physical,2007,3(4):227234.

［12］Seltzer S J.Developments in alkalimetal atomic magnetometry［D］.Princeton:Princeton University,2008.