Holographic Floquet states I: a strongly coupled Weyl semimetal
Holographic Floquet states I: a strongly coupled Weyl semimetal
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DOI：
10.1007/jhep05(2017)127
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发表时间：
2016-11
影响因子：
5.4
通讯作者：
K. Hashimoto;Shunichiro Kinoshita;Keiju Murata;T. Oka
中科院分区：
文献类型：
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作者：
K. Hashimoto;Shunichiro Kinoshita;Keiju Murata;T. Oka
在连续时间周期扰动驱动的量子系统中，可以实现Floquet态。众所周知，当将自由狄拉克费米子置于旋转电场中时，可以实现一种称为Floquet Weyl半金属的状态。如果在这个系统中引入强相互作用会发生什么？这种相互作用是否会冲掉Weyl半金属的霍尔响应等特征？是否存在一个稳定的状态，它的热力学行为是什么？我们利用大nc极限下旋转电场中= 2超对称无质量QCD中的AdS/CFT对应关系回答了这些问题，实现了“全息Floquet态”的第一个例子。在此极限下，胶子不仅充当相互作用的中介，而且充当能量储存库，稳定非平衡稳态（NESS）。我们得到了旋转电场产生的电流，在高频区满足欧姆定律，而在低频区恢复了直流非线性电导率，这是以前的工作全息得到的。NESS的热力学性质，例如涨落-耗散关系，以有效霍金温度为特征，该温度从有效视界定义，赋予“周期热力学”概念全息意义。在强（泵）旋转电场的基础上，按照凝聚态实验中泵-探针实验的精神，我们附加了一个弱（探针）电场。背景旋转电场下的弱直流和交流探针分析表明，霍尔电流为线性响应，因此Floquet Weyl半金属的霍尔响应存在于强耦合极限。我们还发现频率混合响应电流，即外差效应，周期性驱动的Floquet系统的特征。
Floquet states can be realized in quantum systems driven by continuous time-periodic perturbations. It is known that a state known as the Floquet Weyl semimetal can be realized when free Dirac fermions are placed in a rotating electric field. What will happen if strong interaction is introduced to this system? Will the interaction wash out the characteristic features of Weyl semimetals such as the Hall response? Is there a steady state and what is its thermodynamic behavior? We answer these questions using AdS/CFT correspondence in the= 2 supersymmetric massless QCD in a rotating electric field in the large N c limit realizing the first example of a “holographic Floquet state”. In this limit, gluons not only mediate interaction, but also act as an energy reservoir and stabilize the nonequilibrium steady state (NESS). We obtain the electric current induced by a rotating electric field: in the high frequency region, the Ohm’s law is satisfied, while we recover the DC nonlinear conductivity at low frequency, which was obtained holographically in a previous work. The thermodynamic properties of the NESS, eg, fluctuation-dissipation relation, is characterized by the effective Hawking temperature that is defined from the effective horizon giving a holographic meaning to the “periodic thermodynamic” concept. In addition to the strong (pump) rotating electric field, we apply an additional weak (probe) electric field in the spirit of the pump-probe experiments done in condensed matter experiments. Weak DC and AC probe analysis in the background rotating electric field shows Hall currents as a linear response, therefore the Hall response of Floquet Weyl semimetals survives at the strong coupling limit. We also find frequency mixed response currents, ie, a heterodyning effect, characteristic to periodically driven Floquet systems.