三維光晶格和原位測量-物理所BEC研究展望(PPT課件)

1、王如泉中國科學(xué)院物理研究所第五屆全國冷原子物理和量子信息青年學(xué)者學(xué)術(shù)討論會(huì)蘭州大學(xué) 2010. 8. 41. Why is in situ imaging important2. The BEC setup at IOP and our in situ imaging plan3. The 87Rb-40K-23Na(6Li) project at IOPBEC coherent macroscopic matter wavelamplaserVortex in BEC(JILA group, 2000)Matter wave interference(MIT group, 1997)BEC

2、of BEC of 87Rb(JILA group, 1995)Ideal platform for Ultra low temperature quantum physicsMatter wave laser(MPQ group, 2000)強(qiáng)關(guān)聯(lián)多體物理：強(qiáng)關(guān)聯(lián)多體物理：是物理學(xué)尚未攻克的難關(guān)，又是決定諸多材料物性的關(guān)鍵（鐵磁性，巨磁電阻，重費(fèi)米子，高溫超導(dǎo)等）原因原因: :1.多體波函數(shù),全量子系統(tǒng)2.非線性系統(tǒng)，無法用微擾論處理數(shù)值仿真數(shù)值仿真計(jì)算資源隨系統(tǒng)粒子數(shù)指數(shù)增長解決方案之一：解決方案之一： 用量子計(jì)算機(jī)仿真量子系統(tǒng) 新材料探索: 超導(dǎo), 磁性等量子計(jì)算機(jī): 光晶格中的原子氣基

3、本模型研究: Hubbard模型, Heisenberg模型等Quantum simulation of many body physics什么是量子仿真什么是量子仿真? ?Qi Zhou et al, PRL 103, 085701 (2009)Quantum simulation of many body physicsQi Zhou et al, PRL 103, 085701 (2009)Quantum degenerate Bose/Fermi system below micro KelvinOptical lattice provide periodical potential

4、with no defectsAtom-atom interaction can be described by a simple s-wave scattering lengthEasily tunable Hubbard Model parametersArtificial toy models: 1D, 2D, spinor, etcSuper fluid to Mott insulator phase transition in 3-D optical latticeGreiner M., Mandel O., Esslinger T., Hansch T. W. & Bloc

5、h I., Nature 415, 3944 (2002).First quantum simulation experiment looks beautiful, but faces a lot of questions3D optical latticeLack of a clear diagnostic of how to identify phases Complications due to coexistence of different phases in the same confining potentialLack of thermometry of the Bose ga

6、s in the optical latticeTime of flight (TOF) imaging0ms10ms20ms30msBEC的相變過程各向異性膨脹TOF imaging of BEC IOPProblem with TOF measurementQi Zhou et al, PRL 103, 085701 (2009)Gemelke, N., Zhang, X., Hung, C.-L. & Chin, Nature, 460, 995 (2009)Absorption imaging of density profile of thin layer cold atom

7、s in 2-D opticallattice with a high numerical aperture imaging lens.In-situ imaging: corner stone setting experiment by Chins group at ChicagoI. Bloch et al, Nature, 467, 68(2010)I. Blochs groups work to resolve single lattice siteMelting of a Mott insulatorW. S. Bakr, J. I. Gillen, M. Greiner et al

8、, Nature, 462, 74(2009) M. Greiners group to achieve single lattice resolutionWedding cake structure of the Mott insulatorW. S. Bakr, M. Greiner et al, Science, 329, 547(2010)What can we achieve with in situ imaging of number densityTin-Lun Ho and Qi Zhou，NATURE PHYSICS 6, 131(2009）Determine the sup

9、erfluid density, temperature and chemical potential of the trapped system with high accuracy, critical for mapping out the phase diagram at finite temperatureQi Zhou et al, PRL 103, 085701 (2009)Single Chamber BEC IOPSingle chamber design vs Double MOT design: advantages and disadvantagesSingle cham

10、berDouble MOTVacuum system1 chamber and 1 set of pumping system2 chambers and 2 sets of pumping systemLaser cooling system6 laser beams13 laser beamsOptical access4 free directions2D optical lattice3 free directions 1D optical latticeNo of atoms1x105(2-5)x105Light-Induced Atomic Desorption for loadi

11、ng a Rubidium Magneto-Optical Trap010203040506070800.05.0 x1081.0 x1091.5x1092.0 x109 500mA 411mA 310mA 200mA 100mA 25mA 0mAatomtime (s)MOT loading at different LED current01002003000.02.0 x1084.0 x108rate decaytime (s)LED current 500mAFast decay 2sSlow decay 50sVacuum restoring time Quadruple trapy

12、xzdBdBdBdxdydz 0B0B Phys. Rev. A, 35, 1535(1987)Phys. Rev. A, 63, 031401(2001)Magnetic atom transfer belt轉(zhuǎn)移線圈冷原子團(tuán)Transfer coils geometry線圈內(nèi)半徑mm外半徑mm厚度mm線直徑mm填充率MOT30.050.015.01.662%TC10.040.015.01.662%QUIC15.050.010.01.662%保持轉(zhuǎn)移方向的磁場梯度為75G/cm重力方向Field Plot during the transferring process MOTBEClattic

13、eImaging lensCCD cameraCCD cameraTransfer coil 3D lattice and Ultra high resolution in situ imaging Large numerical aperture long working distance objectivesCompanyProduct specification Work distance/mmNAZeissEpiplan-Neofluar 50 x/0.55 HD DIC M279.00.55OlympusSLMPLN100 x7.60.6LeicaHCX PL FLUOTAR L 4

14、0 x/0.60 CORR3.30.6NikonELWD 50 x8.70.55MitutoyoM Plan Apo 100 xG Plan Apo 50 x615.080.70.5Group ObjectiveM. Greiner18mm 0.55(to 0.8)I. Bloch13mm 0.68(Leica)C. ChinResolution 3-4umD. S. Weiss16mm 0.55M. Karski0.29EMCCD cameraGroup CCDM. GreinerEMCCD (Andor Ixon DU888)I. BlochEMCCDC. ChinNot mentione

15、dD. S. WeissEMCCDM. KarskiEMCCDSpatial resolved single photon detectionPrinceton Instrument ProEM: 512B_eXcelon異核偶極分子具有各向異性且長程的偶極-偶極相互作用，是對關(guān)聯(lián)系統(tǒng)研究具有重要意義。玻色-費(fèi)米混合系統(tǒng)（玻色子，費(fèi)米子到極性分子）Quantum degenerate polar molecules偶極晶體相變，多體偶極量子氣，量子信息，超冷化學(xué)量子簡并相干態(tài)轉(zhuǎn)化New. J. Phys., 11, 055049(2009) 簡并玻色-費(fèi)米混合系統(tǒng)是得到超冷分子的最優(yōu)手段超冷分

16、子的重要科學(xué)意義基態(tài)冷分子制備偶極分子的各向異性超冷化學(xué)中的量子統(tǒng)計(jì)特性Nature, 424, 47(2003), Science, 301, 1510 (2003), Phys. Rev. Lett. 100, 143201 (2008). Nature Physics 4, 622 (2008), Phys. Rev. Lett. 100, 143201 (2008), Science, 322, 231 (2008), Science, 327, 853 (2010), Nature, 464, 1324(2010) 1.銣-鉀分子偶極矩太小2.銣-鉀分子在超冷碰撞中不穩(wěn)定激發(fā)態(tài)冷分子

17、制備新的原子選擇的必要性和優(yōu)勢：40K-23Na40K-23Na具有更大的偶極矩和超冷化學(xué)反應(yīng)的穩(wěn)定性，是所有可能中的最佳組合87Rb-40K-23Na（或6Li）混合冷卻系統(tǒng)相對碰撞截面Rb-Rb1K-Rb2Li-K0.2Li-Li0.1Na-Na0.72Na-K？偶極矩(Debeye)穩(wěn)定性E(cm-1)Li-Na0.56-328Li-K3.6-534Li-Rb4.2-618Li-Cs5.5-415Na-K2.874.3K-Rb0.6-8.7K-Cs1.937.8 J. Chem. Phys. 122,204302 (2005)31The 87Rb-40K-23Na(6Li) projec

18、t at IOP23Na和7Li同一塞曼減速器和同一套染料激光轉(zhuǎn)移線圈以實(shí)現(xiàn)三維光晶格和原位測量磁阱原位測量空間分辨優(yōu)于2微米32銣原子冷卻激光系統(tǒng)鉀原子冷卻激光系統(tǒng)鈉原子冷卻激光系統(tǒng)33Cooling laser for Rb and K25oC下自由運(yùn)轉(zhuǎn)波長783nm的激光管冷卻到-50oC得到767nm，0.2nm/oC。困難：冷卻到-50C熱負(fù)載很大且有結(jié)露問題，解決方法：真空隔熱和三級制冷。Cooling laser for Lithium cooling laser for Li Complete injection lockingpartial injection locking multimodenot injection locking8mw inject