Nonlinear atom interferometer surpasses classical precision limit

By C. Gross, T. Zibold, E. Nicklas, J. Estève, Markus K. Oberthaler. Nature, 2010

779 citations recorded by the source corpus.

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. 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. 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. Extending quantum interferometry 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 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.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/66704007d06292aae768e8e0bcafe59aa63fbb8f

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Citations in the corpus

Spinor Bose gases: Symmetries, magnetism, and quantum dynamics (2013, background): “…of the vector spin for gases of spin-1/2 atoms (Takano et al., 2009) and also higher-spin atoms (Kuzmich et al., 1998, 2000), and for pseudo-spin-1/2 systems (Appel et al., 2009; Esteve et al., 2008; Gross et al., 2010; Hammerer et al., 2010; Riedel et al., 2010; SchleierSmith et al., 2010).”
Spin squeezing, entanglement and quantum metrology with Bose–Einstein condensates (2012, methodology): “We focus here on another method exploiting an interstate Feshbach resonance between two hyperfine states of Rubidium around 9 G [60] (3).”
Spin-nematic squeezed vacuum in a quantum gas (2011, background): “1 with the help of the spin SU(2) subspace {Sx ,Sy ,Sz} and both of the subspaces that exhibit squeezing, {Sx ,Qyz ,Qzz} and {Sy ,Qxz ,Qzz} (Supplementary Information).”
Quantum-enhanced measurements without entanglement (2017, background): “So far the best experimentally demonstrated approximations to Fock states with massive bosons are number-squeezed states with a few dB of squeezing (Esteve et al., 2008; Gross et al., 2010b; Riedel et al., 2010b).”
Models of Wave-function Collapse, Underlying Theories, and Experimental Tests (2012, background): “External electro-magnetic fields have to be shielded by a Faraday cage of the right dimensions and materials, where recent technological progress has been made for the stabilization of magnetic fields in atom experiments (Gross et al., 2010).”
Quantum metrology with nonclassical states of atomic ensembles (2016, methodology): “Spin squeezing obtained via one-axis twisting dynamics in a Bose-Einstein condensate has been first experimentally demonstrated by Gross et al. (2010) and Riedel et al. (2010).”
Macroscopic quantum states: Measures, fragility, and implementations (2017, methodology): “Gross et al. (2010) reported on spin squeezing with 2300 atoms and ξ2 ≈ −8.2dB in a Bose-Einstein condensate, through Feshbach control of interactions in an optical trap.”
Quantum spin squeezing (2010, background): “The particle collisions induced decoherence in the generation of spin squeezing was studied in [151], and spin-squeezed states generated in BEC are robust to dissipation [152], and particle losses [126, 153, 154].”
Comparing and contrasting nuclei and cold atomic gases (2013, background): “However, very recent experiments have now started utilizing narrow resonances (Gross et al. 2010).”
Quantum limits in optical interferometry (2014, background): “Analogous schemes may also be implemented in BEC (Cronin et al., 2009; Gross et al., 2010).”
Time-Dependent Impurity in Ultracold Fermions: Orthogonality Catastrophe and Beyond (2012, background): “While it was originally designed for metrology applications, it has been realized recently that it can also be used as a probe of many-body dynamics [8,61–65].”