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本文实验测量了无相互作用下6Li超冷费米原子气体密度分布的空间噪声涨落. 在量子简并条件下, 研究了理想费米气体的空间原子噪声涨落和量子简并度之间的关系, 在实验上研究了泡利排斥对量子简并费米气体密度涨落的有效抑制, 实现了低温费米量子气体的亚泊松分布测量. 本文发展的原子密度噪声测量方法和测量结果在强相关多体系统的温度测量和观测不可压缩量子相的相变方面具有较大的应用前景.
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关键词:
- 无相互作用 /
- 6Li量子简并费米气体 /
- 泡利抑制 /
- 密度涨落
In this paper, we study the spatial noise fluctuations of the density distribution of non-interacting 6Li ultracold Fermi gases. For ideal ultracold Fermi gases, the Fermi-Dirac statistics governs its quantum distribution. The suppression of density fluctuations at low temperature, due to Pauli exclusion principle, is observed in a large cloud of fermions. To clearly reveal the density noise fluctuations of the ideal Fermi gases, other noises, such as the background noise, imaging laser noise, CCD photon counting noise, are greatly suppressed. The noise fluctuation shows a sub-Poissonian statistics in excess of 10,000 atoms per spin state. The dependence of the spatial atom noise fluctuation on the quantum degeneracy is also investigated by changing the temperature of the degenerated Fermi gases. The Fermi gases with lower temperature exhibit larger suppression of the noise fluctuations. The results may have great applications in measuring the temperature of strongly correlated many-body physics and observing the phase transition of incompressible quantum phases.-
Keywords:
- ideal Fermi gas /
- 6Li quantum degenerate Fermi gas /
- Pauli suppression /
- density fluctuations
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Yuan D Q 2016 Acta Phys. Sin. 65 180302Google Scholar
[15] 刁鹏鹏, 邓书金, 李芳, 武海斌 2019 物理学报 68 046702Google Scholar
Diao P P, Deng S J, Li F, Wu H B 2019 Acta Phys. Sin. 68 046702Google Scholar
[16] Esteve J, Trebbia J B, Schumm T, Aspect A, Westbrook C I, Bouchoule I 2006 Phys. Rev. Lett. 96 130403Google Scholar
[17] Armijo J 2012 Phys. Rev. Lett. 108 225306Google Scholar
[18] Whitlock S, Ockeloen C F, Spreeuw R J C 2010 Phys. Rev. Lett. 104 120402Google Scholar
[19] Esteve J, Gross C, Weller A, Giovanazzi S, Oberthaler M K 2008 Nature 455 1216Google Scholar
[20] Itah A, Veksler H, Lahav O, Blumkin A, Moreno C, Gordon C, Steinhauer J 2010 Phys. Rev. Lett. 104 113001Google Scholar
[21] Tobias W G, Matsuda K, Valtolina G, Marco L D, Li J, Ye J 2020 Phys. Rev. Lett. 124 033401Google Scholar
[22] Jördens R, Strohmaier N, Günter K, Moritz H, Esslinger T 2008 Nature 455 204Google Scholar
[23] Werner F, Parcollet O, Georges A, Hassan S R 2005 Phys. Rev. Lett. 95 056401Google Scholar
[24] Deng S, Diao P, Yu Q, Wu H 2015 Chin. Phys. Lett. 32 052401Google Scholar
[25] Deng S, Shi Z, Diao P, Yu Q, Zhai H, Qi R, Wu H 2016 Science 353 371Google Scholar
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图 3 不同温度下原子数涨落Var(N)与平均原子数
$\left\langle N \right\rangle $ 的关系. 红色为高温${T=}{0.7}{{T}}_{\rm{F}}$ , 蓝色为低温${T=}{0.3}{{T}}_{\rm{F}}$ , 红色虚线是对高温数据密度较低时的拟合, 斜率为0.55, 这个数值反映了系统真实的散射截面为理论值的55%Fig. 3. The relationship between the fluctuation of atomic number and the average atomic number at different temperatures. Red is high temperature
${T=}{0.7}{{T}}_{\rm{F}}$ , blue is low temperature${T=}{0.3}{{T}}_{\rm{F}}$ , red dotted line is the fitting of high temperature data with low density, and the slope is 0.55, which reflects that the real scattering cross section of the system is 55% of the theoretical value.图 4 不同温度下原子密度与密度涨落的比较 (a)
${T}{=}{0.}{3}{{T}}_{\rm{F}}$ ; (b)${T}{=}{0.7}{{T}}_{\rm{F}}$ . 图中左侧为原子密度分布, 右侧为密度涨落Fig. 4. Comparison of atomic density and density fluctuation at different temperatures: (a)
${T}{=}{0.}{3}{{T}}_{\rm{F}}$ ; (b)${T}{=}{0.7}{{T}}_{\rm{F}}$ . In figure (a) (b), the distribution of atomic density is on the left, and the density fluctuation is on the right. -
[1] Zheng H, Bonasera A 2011 Phys. Lett. B 696 178Google Scholar
[2] Zheng H, Giuliani G, Bonasera A 2012 Nucl. Phys. A 892 43Google Scholar
[3] Sanner C, Su E J, Huang W, Keshet A, Gillen J, Ketterle W 2012 Phys. Rev. Lett. 108 240404Google Scholar
[4] Sanner C, Su E J, Keshet A, Huang W, Gillen J, Gommers R, Ketterle W 2011 Phys. Rev. Lett. 106 010402Google Scholar
[5] Altman E, Demler E, Lukin M D 2004 Phys. Rev. A 70 013603Google Scholar
[6] Bruun G M, Syljuåsen O F, Pedersen K G L, Andersen B M, Demler E, Sørensen A S 2009 Phys. Rev. A 80 033622Google Scholar
[7] Singh V P, Mathey L 2014 Phys. Rev. A 89 053612Google Scholar
[8] Guarrera V, Fabbri N, Fallani L, Fort C, Stam V D, Inguscio M 2008 Phys. Rev. Lett. 100 250403Google Scholar
[9] Petrov D S, Salomon C, Shlyapnikov G V 2004 Phys. Rev. Lett. 93 090404Google Scholar
[10] DeMarco B, Papp B S, Jin D S 2001 Phys. Rev. Lett. 86 5409Google Scholar
[11] Sanner C, Su E J, Keshet A, Gommers R, Shin Y, Huang W, Ketterle W 2010 Phys. Rev. Lett. 105 040402Google Scholar
[12] Müller T, Zimmermann B, Meineke J, Brantut J, Esslinger T, Moritz H 2010 Phys. Rev. Lett. 105 040401Google Scholar
[13] Chen X W, Liu Z Q, Kong X M 2014 Chin. Phys. B 23 026701Google Scholar
[14] 袁都奇 2016 物理学报 65 180302Google Scholar
Yuan D Q 2016 Acta Phys. Sin. 65 180302Google Scholar
[15] 刁鹏鹏, 邓书金, 李芳, 武海斌 2019 物理学报 68 046702Google Scholar
Diao P P, Deng S J, Li F, Wu H B 2019 Acta Phys. Sin. 68 046702Google Scholar
[16] Esteve J, Trebbia J B, Schumm T, Aspect A, Westbrook C I, Bouchoule I 2006 Phys. Rev. Lett. 96 130403Google Scholar
[17] Armijo J 2012 Phys. Rev. Lett. 108 225306Google Scholar
[18] Whitlock S, Ockeloen C F, Spreeuw R J C 2010 Phys. Rev. Lett. 104 120402Google Scholar
[19] Esteve J, Gross C, Weller A, Giovanazzi S, Oberthaler M K 2008 Nature 455 1216Google Scholar
[20] Itah A, Veksler H, Lahav O, Blumkin A, Moreno C, Gordon C, Steinhauer J 2010 Phys. Rev. Lett. 104 113001Google Scholar
[21] Tobias W G, Matsuda K, Valtolina G, Marco L D, Li J, Ye J 2020 Phys. Rev. Lett. 124 033401Google Scholar
[22] Jördens R, Strohmaier N, Günter K, Moritz H, Esslinger T 2008 Nature 455 204Google Scholar
[23] Werner F, Parcollet O, Georges A, Hassan S R 2005 Phys. Rev. Lett. 95 056401Google Scholar
[24] Deng S, Diao P, Yu Q, Wu H 2015 Chin. Phys. Lett. 32 052401Google Scholar
[25] Deng S, Shi Z, Diao P, Yu Q, Zhai H, Qi R, Wu H 2016 Science 353 371Google Scholar
[26] Bruun M, Clark C W 2000 Phys. Rev. A 61 061601(R)Google Scholar
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