The difference in noise property between the Autler-Townes splitting medium and the electromagnetically induced transparent medium

The quantum noise of squeezed probe light passing through an atomic system with different electromagnetically induced transparency and Autler-Townes splitting effects is investigated theoretically.It is found that the optimal squeezing preservation of the outgoing probe beam occurs in the strong-coupling-field regime rather than in the weakcoupling-field regime.In the weak-coupling-field regime,which was recently recognized as the electromagnetically induced transparency regime(Abi-Salloum T Y 2010 Phys.Rev.A 81 053836),the output amplitude noise is affected mainly by the atomic noise originating from the random decay process of atoms.While in the strong-coupling-field regime,defined as the Autler-Townes splitting regime,the output amplitude noise is affected mainly by the phase-toamplitude conversion noise.This is useful in improving the quality of the experiment for efficient quantum memory,and hence has an application in quantum information processing.     

Optically tunable photonic stop bands in homogeneous absorbing media

Resonantly absorbing media supporting electromagnetically induced transparency may give rise to specific periodic patterns where a light probe is found to experience a fully developed photonic band gap yet with negligible absorption everywhere. In ultracold atomic samples the gap is found to arise from spatial regions where Autler-Townes splitting and electromagnetically induced transparency alternate with one another and detailed calculations show that accurate and efficient coherent optical control of the gap can be accomplished. The remarkable experimental simplicity of the control scheme would ease quantum nonlinear optics applications.     

Evidence of Autler-Townes splitting in high-order nonlinear processes

We demonstrate Autler-Townes (AT) splitting of four-wave mixing in an electromagnetically induced transparency window, which results from the destructive interference between a three-photon process and a five-photon process. The primary and secondary AT splittings are achieved via induced atomic coherence in a four-level Y-type atomic system. Theoretical calculations fit well with the experimentally measured results. Such controlled multichannel splitting of nonlinear optical signals can have potential applications in optical communication and quantum information processing.     

Observations of Autler-Townes spatial splitting of four-wave mixing image

We report the self- and external-dressed Autler-Townes (A-T) splittings of the images of the generated four-wave mixing signal (FWM) and electromagnetically induced transparency (EIT) of probe images in cascade three-level atomic system. Such spatial properties of probe and FWM signals are induced by the enhanced cross-Kerr nonlinearity. We demonstrate the controlled electromagnetically induced spatial dispersion (EISD), splitting and focusing of probe and FWM signals images by adjusting self- and external-dressing fields. Studies on such controllable A-T spatial splitting and spatial EIT effect can be very useful in applications of spatial signal processing and optical communication.     

Objectively discerning Autler-Townes splitting from electromagnetically induced transparency

Autler-Townes splitting (ATS) and electromagnetically induced transparency (EIT) both yield transparency in an absorption profile, but only EIT yields strong transparency for a weak pump field due to Fano interference. Empirically discriminating EIT from ATS is important but so far has been subjective. We introduce an objective method, based on Akaike's information criterion, to test ATS vs EIT from experimental data for three-level atomic systems and determine which pertains. We apply our method to a recently reported induced-transparency experiment in superconducting-circuit quantum electrodynamics.     

A proposal for the implementation of a quantum phase gate in a five-level atomic medium

The interaction of a five-level atomic system involving electromagnetically induced transparency with four light fields is investigated. Two different operating regimes are considered, semi-classical and quantized, where two light fields are treated as quantum. In the semi-classical regime, the dispersive properties of the scheme are analyzed in detail, and the conditions leading to group velocity matching for two of the light fields are identified. In the quantized regime, the two quantum fields undergo cross-phase modulation induced by electromagnetically induced transparency. Based on this, a recent proposal [C. Ottaviani et al., Phys. Rev. A 73, 010301 (R) (2006)] for a two-qubit quantum phase gate for traveling single-photon qubits is examined. An experimental scheme for verification of QPG operation is proposed.     

里德伯电磁感应透明中的相位

本文在典型的里德伯电磁感应透明系统中研究弱探测场在相互作用原子系统中的传播特性,重点关注基于偶极阻塞效应的探测场相位的合作光学非线性行为.通过与探测场透射率和光子关联作对比,发现相位的光学响应具有新特性:共振和Autler-Townes劈裂条件下相位对入射场强和初始光子关联不敏感,而在两者之间的频率范围内相位响应具有非线性特征,尤其在经典光频率处最显著.此外,提高主量子数和原子密度都会促进相位的非线性效应.综上,与探测场透射率和光子关联一样,相位可以作为合作光学非线性的另一个标识来刻画非线性现象,对里德伯电磁感应透明研究是一个有力的补充.     

Multi-wave mixing Autler-Townes splitting in the five-level atomic system

We have demonstrated the Autler-Townes (AT) splitting of the four-wave mixing (FWM) process and the six-wave mixing (SWM) process in an electromagnetically induced transparency (EIT) window in five-level atomic vapor of 87 Rb. Moreover we discuss interactions of multi-dressed states. The experimental results agree well with the theoretical analysis.     

Tripod型双电磁诱导透明原子系统中压缩光的传输

采用海森堡-朗之万方法理论研究了Tripod型双电磁诱导透明原子系统中压缩态探针场的传输特性.研究结果表明:通过双透明窗口压缩光可实现双通道传输,且每个通道可以被独立操控;当两束耦合场的频率失谐相等时,输出探针场的压缩度可以得到更好的保持.此外,输出探针场的压缩度可以通过耦合场的拉比频率、原子的光学厚度和基态退相干率以及探测频率来操控.该研究结果为进一步优化多通道量子存储提供依据.     

电磁诱导吸收介质中探针场的量子噪声特性

在N型原子系统中,在二束强的耦合场作用于介质对探针场体现出很强的诱导吸收作用,与此同时,强吸收引起的自发辐射噪声会影响探针场的量子噪声特性.该文章研究了输入的量子化探测场在经过电磁诱导吸收介质后的噪声特性变化,数值模拟得出,通过调节控制场的强度可以使得探测场的噪声谱图形在吸收窗口范围内产生震荡分裂,噪声最小值处于一定的探针场失谐处.