论文标题
从$ w $到greenberger-horne-Zeilinger国家的量子 - 布拉基施氏酮方法rydberg-atom Qubits
Quantum-brachistochrone approach to the conversion from $W$ to Greenberger-Horne-Zeilinger states for Rydberg-atom qubits
论文作者
论文摘要
我们使用量子 - 布拉基施施隆形式主义，我们解决了在$ W $和Greenberger-Horne-Zeilinger（GHz）态之间找到最快（时间优势）确定性转换的问题，该系统在三个相同且相等的中性原子的系统中，这些原子由四种外部激光脉冲作用于四种外部激动。假设所有四种脉冲都接近与相同的内部（原子）过渡（原子基态状态和高倾斜的Rydberg州之间的脉冲），则每个脉冲都可以视为有效的两级系统（$ GR $ $ -GR $ -TYPE QUBIT）。从有效的哈密顿式系统开始，该系统在Rydberg-Blockade制度中是有效的，并在四态歧管上定义，我们得出了与最快$ W $ -W $ -TO-GHz状态转换有关的量子 - 支架方程。通过数值求解这些方程式，我们确定与时间 - 最佳状态转换相对应的外部激光脉冲的时间依赖性的RABI频率。 In particular, we show that the shortest possible $W$-to-GHZ state-conversion time is given by $T_{\textrm{QB}}= 6.8\:\hbar/E$, where $E$ is the total laser-pulse energy used, this last time being significantly shorter than the state-conversion times previously found using a dynamical-symmetry-based approach [$ t _ {\ textrm {ds}} =（1.33-1.66）\：t _ {\ textrm {qb}} $]。
Using the quantum-brachistochrone formalism, we address the problem of finding the fastest possible (time-optimal) deterministic conversion between $W$ and Greenberger-Horne-Zeilinger (GHZ) states in a system of three identical and equidistant neutral atoms that are acted upon by four external laser pulses. Assuming that all four pulses are close to being resonant with the same internal (atomic) transition -- the one between the atomic ground state and a high-lying Rydberg state -- each atom can be treated as an effective two-level system ($gr$-type qubit). Starting from an effective system Hamiltonian, which is valid in the Rydberg-blockade regime and defined on a four-state manifold, we derive the quantum-brachistochrone equations pertaining to the fastest possible $W$-to-GHZ state conversion. By numerically solving these equations, we determine the time-dependent Rabi frequencies of external laser pulses that correspond to the time-optimal state conversion. In particular, we show that the shortest possible $W$-to-GHZ state-conversion time is given by $T_{\textrm{QB}}= 6.8\:\hbar/E$, where $E$ is the total laser-pulse energy used, this last time being significantly shorter than the state-conversion times previously found using a dynamical-symmetry-based approach [$T_{\textrm{DS}}=(1.33-1.66)\:T_{\textrm{QB}}$].
