三維光晶格和原位測量

1、2021/3/2712021/3/2721. Why is in situ imaging important2. The BEC setup at IOP and our in situ imaging plan3. The 87Rb-40K-23Na(6Li) project at IOP2021/3/273BEC coherent macroscopic matter wavelamplaserVortex in BEC(JILA group, 2000)Matter wave interference(MIT group, 1997)BEC of 87Rb(JILA group, 19

2、95)Ideal platform for Ultra low temperature quantum physicsMatter wave laser(MPQ group, 2000)2021/3/274強關聯多體物理:是物理學尚未攻克的難關,又是決定諸多材料物性的關鍵（鐵磁性,巨磁電阻,重費米子,高溫超導等）原因:1.多體波函數,全量子系統2.非線性系統,無法用微擾論處理數值仿真計算資源隨系統粒子數指數增長解決方案之一: 用量子計算機仿真量子系統 新材料探索: 超導, 磁性等量子計算機: 光晶格中的原子氣基本模型研究: Hubbard模型, Heisenberg模型等Quantum sim

3、ulation of many body physics什么是量子仿真?Qi Zhou et al, PRL 103, 085701 (2009)2021/3/275Quantum simulation of many body physicsQi Zhou et al, PRL 103, 085701 (2009)2021/3/276Quantum degenerate Bose/Fermi system below micro KelvinOptical lattice provide periodical potential with no defectsAtom-atom intera

4、ction 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. & Bloch I., Nature 415, 3944 (2002).F

5、irst 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 gas in the optical lattice2021/3/

6、277Time of flight (TOF) imaging2021/3/2780ms10ms20ms30msBEC的相變過程各向異性膨脹TOF imaging of BEC IOP2021/3/279Problem with TOF measurementQi Zhou et al, PRL 103, 085701 (2009)2021/3/2710Gemelke, N., Zhang, X., Hung, C.-L. & Chin, Nature, 460, 995 (2009)Absorption imaging of density pro thin layer cold a

7、toms in 2-D opticallattice with a high numerical aperture imaging lens.In-situ imaging: corner stone setting experiment by Chins group at Chicago2021/3/2711I. Bloch et al, Nature, 467, 68(2010)I. Blochs groups work to resolve single lattice site2021/3/2712Melting of a Mott insulator2021/3/2713W. S.

8、Bakr, J. I. Gillen, M. Greiner et al, Nature, 462, 74(2009) M. Greiners group to achieve single lattice resolution2021/3/2714Wedding cake structure of the Mott insulatorW. S. Bakr, M. Greiner et al, Science, 329, 547(2010)2021/3/2715What can we achieve with in situ imaging of number densityTin-Lun H

9、o and Qi Zhou,NATURE PHYSICS 6, 131(2009）Determine the superfluid 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)2021/3/2716Single Chamber BEC IOP2021/3/2717Sin

10、gle chamber design vs Double MOT design: advantages and disadvantagesSingle chamberDouble 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 o

11、ptical latticeNo of atoms1x105(2-5)x1052021/3/2718Light-Induced Atomic Desorption for loading a Rubidium Magneto-Optical Trap2021/3/2719010203040506070800.05.0 x1081.0 x1091.5x1092.0 x109 500mA 411mA 310mA 200mA 100mA 25mA 0mAatomtime (s)MOT loading at different LED current2021/3/272001002003000.02.

12、0 x1084.0 x108rate decaytime (s)LED current 500mAFast decay 2sSlow decay 50sVacuum restoring time 2021/3/2721Quadruple trapyxzdBdBdBdxdydz 0B0B Phys. Rev. A, 35, 1535(1987)2021/3/2722Phys. Rev. A, 63, 031401(2001)Magnetic atom transfer belt轉移線圈冷原子團2021/3/2723Transfer coils geometry線圈內半徑mm外半徑mm厚度mm線直

13、徑mm填充率MOT30.050.015.01.662%TC10.040.015.01.662%QUIC15.050.010.01.662%保持轉移方向的磁場梯度為75G/cm重力方向2021/3/2724Field Plot during the transferring process 2021/3/2725MOTBEClatticeImaging lensCCD cameraCCD cameraTransfer coil 3D lattice and Ultra high resolution in situ imaging 2021/3/2726Large numerical apert

14、ure long working distance objectivesCompanyProduct specification Work distance/mmNAZeissEpiplan-Neofluar 50 x/0.55 HD DIC M279.00.55OlympusSLMPLN100 x7.60.6LeicaHCX PL FLUOTAR L 40 x/0.60 CORR3.30.6NikonELWD 50 x8.70.55MitutoyoM Plan Apo 100 xG Plan Apo 50 x615.080.70.5Group ObjectiveM. Greiner18mm

15、0.55(to 0.8)I. Bloch13mm 0.68(Leica)C. ChinResolution 3-4umD. S. Weiss16mm 0.55M. Karski0.292021/3/2727EMCCD cameraGroup CCDM. GreinerEMCCD (Andor Ixon DU888)I. BlochEMCCDC. ChinNot mentionedD. S. WeissEMCCDM. KarskiEMCCDSpatial resolved single photon detection2021/3/2728Princeton Instrument ProEM:

16、512B_eXcelon2021/3/2729異核偶極分子具有各向異性且長程的偶極-偶極相互作用,是對關聯系統研究具有重要意義。玻色-費米混合系統（玻色子,費米子到極性分子）Quantum degenerate polar molecules偶極晶體相變，多體偶極量子氣，量子信息，超冷化學量子簡并相干態(tài)轉化New. J. Phys., 11, 055049(2009) 簡并玻色-費米混合系統是得到超冷分子的最優(yōu)手段超冷分子的重要科學意義2021/3/2730基態(tài)冷分子制備偶極分子的各向異性超冷化學中的量子統計特性Nature, 424, 47(2003), Science, 301, 1510

17、 (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)冷分子制備2021/3/2731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反應的穩(wěn)定性,是所有可能中的最佳組合8

18、7Rb-40K-23Na（或6Li）混合冷卻系統相對碰撞截面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)The 87Rb-40K-23Na(6Li) project at IOP2021/3/273223Na和7Li同一塞曼減速器和同一套染料激光轉移線圈以實現三維光晶格和原位測量磁阱原位測量空

19、間分辨優(yōu)于2微米2021/3/2733銣原子冷卻激光系統鉀原子冷卻激光系統鈉原子冷卻激光系統2021/3/2734Cooling laser for Rb and K25oC下自由運轉波長783nm的激光管冷卻到-50oC得到767nm,0.2nm/oC。困難:冷卻到-50C熱負載很大且有結露問題,解決方法:真空隔熱和三級制冷。2021/3/2735Cooling laser for Lithium 2021/3/2736cooling laser for Li 2021/3/2737Complete injection lockingpartial injection locking multimodenot injection locking8mw injection 45C7mw injection 45CComplete inject