Zero-Magnetic Field Fractional Quantum States
Zero-Magnetic Field Fractional Quantum States
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DOI：
10.1103/physrevlett.122.086803
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发表时间：
2019-02-28
影响因子：
8.6
通讯作者：
Farrer, I.
中科院分区：
文献类型：
--
作者：
Kumar, S.;Pepper, M.;Farrer, I.
自从1982年分数量子霍尔效应被发现以来，人们一直在理论上讨论在没有量子化磁场形成的朗道能级的情况下电导分数量子化的可能性。虽然理论上已经设想了各种情况，特别是晶格模型中的能带平坦类似于朗道水平，预测的分数从来没有被观察到。在这封信中，我们表明，奇数和偶数分母分数可以观察到，和操纵，在没有量子化磁场的情况下，当一个低密度的电子系统在GaAs基的一维量子线被允许在第二维放松。有人建议，这种弛豫的结果在形成一个锯齿形阵列的电子与环形路径，建立一个循环电流和由此产生的能量降低。已经观察到对称和非对称限制的行为，但增加限制势的非对称性，导致限制的平坦化，增强了新的分数态的出现。我们发现，一个平面内的磁场诱导新的甚至分母分数可能指示电子配对。这里描述的新量子态对低维电子系统的物理学和量子技术都有影响。这项工作将使进一步发展的结构，旨在静电操纵电子形成特定的配置。反过来，这可能会导致设计师定制分数态，以放大未来量子计算中重要的特定属性。
Since the discovery of the fractional quantum Hall effect in 1982 there has been considerable theoretical discussion on the possibility of fractional quantization of conductance in the absence of Landau levels formed by a quantizing magnetic field. Although various situations have been theoretically envisaged, particularly lattice models in which band flattening resembles Landau levels, the predicted fractions have never been observed. In this Letter, we show that odd and even denominator fractions can be observed, and manipulated, in the absence of a quantizing magnetic field, when a low-density electron system in a GaAs based one-dimensional quantum wire is allowed to relax in the second dimension. It is suggested that such a relaxation results in formation of a zigzag array of electrons with ring paths which establish a cyclic current and a resultant lowering of energy. The behavior has been observed for both symmetric and asymmetric confinement but increasing the asymmetry of the confinement potential, to result in a flattening of confinement, enhances the appearance of new fractional states. We find that an in-plane magnetic field induces new even denominator fractions possibly indicative of electron pairing. The new quantum states described here have implications both for the physics of low dimensional electron systems and also for quantum technologies. This work will enable further development of structures which are designed to electrostatically manipulate the electrons for the formation of particular configurations. In turn, this could result in a designer tailoring of fractional states to amplify particular properties of importance in future quantum computation.