Opt Express. 2023 May 8;31(10):16719-16728. doi: 10.1364/OE.486994.
The steerability of a quantum state can be detected by steering inequalities. The linear steering inequalities show that more steerable states can be discovered with the increase of measurements. In order to detect more steerable states in two-photon systems, we first theoretically derive an optimized steering criterion based on infinity measurements for an arbitrary two-qubit state. The steering criterion is only determined by the spin correlation matrix of the state, and do not require infinity measurements. Then, we prepared the Werner-like states in two-photon systems, and measure their spin correlation matrices. Finally, we apply three steering criteria, which include our steering criterion, the three-measurement steering criterion and the geometric Bell-like inequality, to distinguish the steerability of these states. The results show that our steering criterion can detect the most steerable states under the same experimental conditions. Thus, our work provides a valuable reference for detecting the steerability of quantum states.
量子态的可控性可以通过导引不等式来检测。线性导引不等式表明，随着测量次数的增加，可以发现更多可导引的态。为了在双光子系统中检测更多可导引的态，我们首先从理论上推导了任意两量子比特态基于无限次测量的优化导引判据。该导引判据仅由态的自旋关联矩阵决定，并不需要无限次测量。然后，我们在双光子系统中制备了类 Werner 态，并测量了它们的自旋关联矩阵。最后，我们应用了三个导引判据，包括我们的导引判据、三测量导引判据和几何贝尔型不等式，来区分这些态的可导引性。结果表明，在相同的实验条件下，我们的导引判据可以检测到最多的可导引态。因此，我们的工作为检测量子态的可控性提供了有价值的参考。
