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arXiv · 1706.08676

Measurement of complete and continuous Wigner functions for discrete atomic systems

Yali Tian·Zhihui Wang·Pengfei Zhang·Gang Li·Jie Li·Tiancai Zhang
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Abstract

We measure complete and continuous Wigner functions of a two-level cesium atom in both a nearly pure state and highly mixed states. We apply the method [T. Tilma et al., Phys. Rev. Lett. 117, 180401 (2016)] of strictly constructing continuous Wigner functions for qubit or spin systems. We find that the Wigner function of all pure states of a qubit has negative regions and the negativity completely vanishes when the purity of an arbitrary mixed state is less than $\frac{2}{3}$. We experimentally demonstrate these findings using a single cesium atom confined in an optical dipole trap, which undergoes a nearly pure dephasing process. Our method can be applied straightforwardly to multi-atom systems for measuring the Wigner function of their collective spin state.

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Yali Tian, Zhihui Wang, Pengfei Zhang, Gang Li, Jie Li, Tiancai Zhang. 2017-06-27. Measurement of complete and continuous Wigner functions for discrete atomic systems. https://doi.org/10.1103/physreva.97.013840

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