Magnetic adatoms as memory bits: A quantum master equation analysis
Magnetic adatoms as memory bits: A quantum master equation analysis
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DOI：
10.1103/physrevb.91.245430
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发表时间：
2015-02
影响因子：
3.7
通讯作者：
C. Karlewski;M. Marthaler;Tobias Markl;T. Balashov;W. Wulfhekel;G. Schon
中科院分区：
文献类型：
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作者：
C. Karlewski;M. Marthaler;Tobias Markl;T. Balashov;W. Wulfhekel;G. Schon
由于磁性吸附原子的对称性，其基态可能是高度稳定的，这为单原子存储器的应用开辟了前景。一个具体的例子是一个单一的钬原子（与$J=8$）的铂（111）表面上的异常长的寿命在最近的扫描隧道显微镜研究中观察到。为了进行控制和读出，原子必须与电子触点耦合。因此，系统的自旋动力学由量子主方程控制。我们的分析表明，在一般情况下，它不能减少到一个经典的主方程的基础上的未微扰晶体场的哈密顿量。相反，根据参数和控制字段，“环境诱导超选择”原则选择适当的一组基态，这反过来又决定了具体的弛豫通道和寿命。我们的模拟表明，在理想情况下，寿命应该比实验中观察到的更长。因此，我们研究各种扰动的影响。我们还研究了初始化过程中的状态的Ho原子施加电压脉冲，并得出结论，快速，高保真的准备，在100\，\text {ns}$的时间尺度上，应该是可能的。
Due to underlying symmetries the ground states of magnetic adatoms may be highly stable, which opens perspectives for application as single-atom memory. A specific example is a single holmium atom (with $J=8$) on a platinum (111) surface for which exceptionally long lifetimes were observed in recent scanning tunneling microscopy studies. For control and read-out the atom must be coupled to electronic contacts. Hence the spin dynamics of the system is governed by a quantum master equation. Our analysis shows that in general it cannot be reduced to a classical master equation in the basis of the unperturbed crystal-field Hamiltonian. Rather, depending on parameters and control fields, "environment induced superselection" principles choose the appropriate set of basis states, which in turn determines the specific relaxation channels and lifetimes. Our simulations suggest that in ideal situations the lifetimes should be even longer than observed in the experiment. We, therefore, investigate the influence of various perturbations. We also study the initialization process of the state of the Ho atom by applied voltage pulses and conclude that fast, high fidelity preparation, on a $100\,\text{ns}$ timescale, should be possible.