Nonlinear atom interferometer surpasses classical precision limit
Nonlinear atom interferometer surpasses classical precision limit
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DOI：
10.1038/nature08919
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发表时间：
2010-04-22
期刊：
影响因子：
64.8
通讯作者：
Oberthaler, M. K.
中科院分区：
文献类型：
--
作者：
Gross, C.;Zibold, T.;Oberthaler, M. K.
干涉是波动动力学和量子力学的基本原理。粒子的量子波特性在使用原子干涉仪的计量学中得到了利用，从而实现了高精度的惯性测量(1，2)。此外，最先进的时间标准是基于一种被称为拉姆齐光谱的干涉技术。然而，由于用于推断感兴趣数量的原子数量有限，经典统计学限制了干涉仪的精度(3)。在这里，我们通过实验证明，用玻色-爱因斯坦凝聚体的非线性原子干涉术可以超越经典的精度极限。原子之间的受控相互作用导致干涉仪内的非经典纠缠态；这代表了使用非经典输入态的另一种方法(4-8)。将量子干涉法(9)推广到原子数较大的区域，我们发现与理想的经典测量相比，位相灵敏度提高了15%。我们的非线性原子分束器遵循‘一轴扭转’方案(10)，并使用窄的Feshbach共振实现相互作用控制。我们对干涉仪中的量子态进行了噪声层析成像，并探测到了压缩因子为-8.2dB的相干自旋压缩(参考文献11-15)。结果提供了关于多粒子量子态的信息，并暗示了170个原子(16)的纠缠。
Interference is fundamental to wave dynamics and quantum mechanics. The quantum wave properties of particles are exploited in metrology using atom interferometers, allowing for high-precision inertia measurements(1,2). Furthermore, the state-of-the-art time standard is based on an interferometric technique known as Ramsey spectroscopy. However, the precision of an interferometer is limited by classical statistics owing to the finite number of atoms used to deduce the quantity of interest(3). Here we show experimentally that the classical precision limit can be surpassed using nonlinear atom interferometry with a Bose-Einstein condensate. Controlled interactions between the atoms lead to non-classical entangled states within the interferometer; this represents an alternative approach to the use of non-classical input states(4-8). Extending quantum interferometry(9) to the regime of large atom number, we find that phase sensitivity is enhanced by 15 per cent relative to that in an ideal classical measurement. Our nonlinear atomic beam splitter follows the 'one-axis-twisting' scheme(10) and implements interaction control using a narrow Feshbach resonance. We perform noise tomography of the quantum state within the interferometer and detect coherent spin squeezing with a squeezing factor of -8.2 dB (refs 11-15). The results provide information on the many-particle quantum state, and imply the entanglement of 170 atoms(16).