Alexander Byron, Bollinger John J, Uys Hermann
Department of Physics, Stellenbosch University, Stellenbosch Central 7600, Stellenbosch, South Africa.
National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
Phys Rev A (Coll Park). 2020 Jun;101(6). doi: 10.1103/PhysRevA.101.062303.
Many quantum state preparation methods rely on a combination of dissipative quantum state initialization followed by unitary evolution to a desired target state. Here we demonstrate the usefulness of quantum measurement as an additional tool for quantum state preparation. Starting from a pure separable multipartite state, a control sequence, which includes rotation, spin squeezing via one-axis twisting, quantum measurement, and postselection, generates highly entangled multipartite states, which we refer to as (PS) states. Through an optimization method, we then identify parameters required to maximize the overlap fidelity of the PS states with the maximally entangled Greenberger-Horne-Zeilinger (GHZ) states. The method leads to an appreciable decrease in the state preparation time of GHZ states for successfully postselected outcomes when compared to preparation through unitary evolution with one-axis twisting only.
许多量子态制备方法依赖于耗散量子态初始化与酉演化相结合，以达到期望的目标态。在此，我们展示了量子测量作为量子态制备的额外工具的有用性。从一个纯可分多体态开始，一个控制序列，包括旋转、通过单轴扭转实现的自旋压缩、量子测量和后选择，生成高度纠缠的多体态，我们将其称为（PS）态。然后，通过一种优化方法，我们确定了使PS态与最大纠缠的格林伯格 - 霍恩 - 泽林格（GHZ）态的重叠保真度最大化所需的参数。与仅通过单轴扭转的酉演化进行制备相比，该方法在成功进行后选择的结果时，显著减少了GHZ态的态制备时间。
