三维光晶格和原位测量

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强关联多体物理:是物理学尚未攻克的难关,又是决定诸多材料物性的关键（铁磁性,巨磁电阻,重费米子,高温超导等）原因:1.多体波函数,全量子系统2.非线性系统,无法用微扰论处理数值仿真计算资源随系统粒子数指数增长解决方案之一: 用量子计算机仿真量子系统 新材料探索: 超导, 磁性等量子计算机: 光晶格中的原子气基本模型研究: 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的相变过程各向异性膨胀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转移线圈冷原子团2021/3/2723Transfer coils geometry线圈内半径mm外半径mm厚度mm线直

13、径mm填充率MOT30.050.015.01.662%TC10.040.015.01.662%QUIC15.050.010.01.662%保持转移方向的磁场梯度为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异核偶极分子具有各向异性且长程的偶极-偶极相互作用,是对关联系统研究具有重要意义。玻色-费米混合系统（玻色子,费米子到极性分子）Quantum degenerate polar molecules偶极晶体相变，多体偶极量子气，量子信息，超冷化学量子简并相干态转化New. J. Phys., 11, 055049(2009) 简并玻色-费米混合系统是得到超冷分子的最优手段超冷分子的重要科学意义2021/3/2730基态冷分子制备偶极分子的各向异性超冷化学中的量子统计特性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. 铷-钾分子偶极矩太小2. 铷-钾分子在超冷碰撞中不稳定激发态冷分子制备2021/3/2731新的原子选择的必要性和优势:40K-23Na40K-23Na具有更大的偶极矩和超冷化学反应的稳定性,是所有可能中的最佳组合8

18、7Rb-40K-23Na（或6Li）混合冷却系统相对碰撞截面Rb-Rb1K-Rb2Li-K0.2Li-Li0.1Na-Na0.72Na-K?偶极矩(Debeye)稳定性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同一塞曼减速器和同一套染料激光转移线圈以实现三维光晶格和原位测量磁阱原位测量空

19、间分辨优于2微米2021/3/2733铷原子冷却激光系统钾原子冷却激光系统钠原子冷却激光系统2021/3/2734Cooling laser for Rb and K25oC下自由运转波长783nm的激光管冷却到-50oC得到767nm,0.2nm/oC。困难:冷却到-50C热负载很大且有结露问题,解决方法:真空隔热和三级制冷。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