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arXiv:0909.2423 · Physical Review Letters

Manipulation of Nonclassical Atomic Spin States

T. Takano, Shin-Ichi-Ro Tanaka, Ryo Namiki, Yoshiro Takahashi

Published Jan 5, 2010• 23 citations
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Abstract

We report successful manipulation of nonclassical atomic spin states. We apply an off-resonant noncircularly-polarized light pulse to a measurement-induced squeezed spin state of a cold atomic ensemble. By changing the pulse duration, we clearly observe a rotation of the anisotropic quantum-noise distribution in good contrast with the case of manipulation of a coherent spin state where the quantum-noise distribution is always isotropic. This is an important step for quantum state tomography, quantum swapping, and precision spectroscopic measurement.

DOI
10.1103/physrevlett.104.013602

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We report successful manipulation of nonclassical atomic spin states. We apply an off-resonant noncircularly-polarized light pulse to a measurement-induced squeezed spin state of a cold atomic ensemble. By changing the pulse duration, we clearly observe a rotation of the anisotropic quantum-noise distribution in good contrast with the case of manipulation of a coherent spin state where the quantum-noise distribution is always isotropic. This is an important step for quantum state tomography, quantum swapping, and precision spectroscopic measurement.
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We experimentally demonstrate the manipulation of two orthogonal components of a spin wave in an atomic ensemble. Based on Raman two-photon transition and Larmor spin precession induced by magnetic field pulses, the coherent rotations between the two components of the spin wave are controllably achieved. Successively, the two manipulated spin-wave components are mapped into two orthogonal polarized optical emissions. By measuring Ramsey fringes of the retrieved optical signals, the \ensuremath{\pi}/2-pulse fidelity of \ensuremath{\sim}96% is obtained. The presented manipulation scheme can be used to build an arbitrary rotation for qubit operations in quantum information processing based on atomic ensembles.
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