Refractive Index Enhancement with Vanishing Absorption in an Atomic Vapor

微加工原子蒸气室中自旋极化的腔增强探测

Cavity-enhanced detection of spin polarization in a microfabricated atomic vapor cell

本研究在微加工原子蒸气室中结合光学谐振腔与PDH技术，实现了电子自旋极化的无损高灵敏度探测，验证了理论模型并标定了光泵浦参数，达到量子噪声极限的探测水平。

Optical quantum memory for ultrafast photons using molecular alignment

The absorption of broadband photons in atomic ensembles requires either an effective broadening of the atomic transition linewidth, or an off-resonance Raman interaction. Here we propose a scheme for a quantum memory capable of storing and retrieving ultrafast photons in an ensemble of two-level atoms by using a propagation medium with a time-dependent refractive index generated from aligning an ensemble of gas-phase diatomic molecules. The refractive index dynamics generates an effective longitudinal inhomogeneous broadening of the two-level transition. We numerically demonstrate this scheme …

Interference at quantum transitions: lasing without inversion and resonant four-wave mixing in strong fields at Doppler-broadened transitions

An influence of nonlinear interference processes at quantum transitions under strong resonance electromagnetic fields on absorption, amplification and refractive indices as well as on four-wave mixing processes is investigated. Doppler broadening of the coupled transitions, incoherent excitation, relaxation processes, as well as power saturation processes associated with the coupled levels are taken into account. Both closed (ground state is involved) and open (only excited states are involved) energy level configurations are considered. Common expressions are obtained which allow one to analy…

通过折射率增强的等离激元类比实现超大尺寸主动可调光子带隙

Ultra-large actively tunable photonic band gaps via plasmon-analog of index enhancement

该研究提出利用折射率增强的等离激元类比，通过泵浦脉冲连续调控纳米棒二聚体周期结构的折射率，在近零损耗下实现超大光子带隙的主动开启与调谐，并经Maxwell方程数值验证，可用于数十飞秒线性光子开关。

Enhanced index of refraction in four-wave mixing media

Refractive index enhancement accompanied by vanishing absorption in a four-level atomic system interacting with two control and two probe fields in a regime of four-wave mixing (FWM) has been predicted and studied in the present work. We analyzed the maximal index enhancement in the four-level FWM system and gave index estimates for a real atomic gas of $^{40}$K, taking into account its multilevel structure and collisional and Doppler broadenings at large atomic densities. We also discussed how vanishing absorption with no nearby amplification can be realized in a two species system, consistin…

Index of refraction engineering in five level DIGS atoms

We present a five level atomic system in which the index of refraction of a probe laser can be enhanced or reduced below unity with vanishing absorption in the region between pairs of absorption and gain lines formed by dressing of the atoms with a control laser and RF/microwave fields. By weak incoherent pumping of population into a single metastable state, one can create several narrow amplifying resonances. At frequencies between these gain lines and additional absorption lines, there exist regions of vanishing absorption but resonantly enhanced index of refraction. In $Rb$ vapors with dens…

基于 metamaterial GRIN 镜的量子 Rydberg 原子 RF 接收机灵敏度增强实验

Experimental Sensitivity Enhancement of a Quantum Rydberg Atom-Based RF Receiver with a Metamaterial GRIN Lens

本研究通过 GRIN 镜增强基于 Rydberg 原子的 RF 接收机灵敏度，验证了 metamaterial 在量子 RF 感知中的应用潜力。