磁光旋转的相干控制

相干态的位移转动

Displaced rotations of coherent states

我们提出了一种方法，使它能够用于构造相干态的旋转，特别是，它给出了一种可能性，构造Hadamard门的相干态。我们的方法是基于表示的任意单模纯态在自由旅行的领域，特别是叠加的相干态（SCS），在位移的任意振幅的位移数的状态。所研究的光学方案是基于交替的光子添加和位移算子（在一般情况下，光子添加和位移是必需的）与种子相干态，以产生偶数和奇数位移压缩SCS（DSSCS），而不管所使用的光子添加的数量。结果表明，在其他参数不变的情况下，所研究的光学方案对种子相干态敏感。输出态可以高保真地近似于偶压缩的SCS或相对位移一定值的奇SCS。它使相干态的局域旋转算符的构造成为可能，特别是Hadamard门成为相干态量子计算的基本单元。考虑了输出态质量恶化的影响。

相干驱动三脚架原子的磁光旋转和交叉相位调制

Magneto-optical rotation and cross-phase modulation via coherently driven tripod atoms

研究了具有两个正交偏振分量的弱探测场与三脚架形四能级原子光学稠密介质的相互作用。在存在相干驱动激光的情况下，在介质中实现电磁诱导透明，显著增强其线性和非线性色散，同时抑制探测场吸收。我们提出了系统的半经典和全量子分析。我们提出了一个实验上可行的设置，可以诱导大法拉第旋转的探测场的偏振，因此可用于超灵敏的光学磁强计。然后，我们研究了探测器的两个组件之间的克尔非线性耦合，展示了一种对称的，非常有效的交叉相位调制的新制度，能够完全纠缠两个单光子脉冲。该方案为基于光子的量子信息应用，如确定性全光量子计算、密集编码和隐形传态等奠定了基础。

Optimal Detection of Rotations about Unknown Axes by Coherent and Anticoherent States

Coherent and anticoherent states of spin systems up to spin j=2 are known to be optimal in order to detect rotations by a known angle but unknown rotation axis. These optimal quantum rotosensors are characterized by minimal fidelity, given by the overlap of a state before and after a rotation, averaged over all directions in space. We calculate a closed-form expression for the average fidelity in terms of anticoherent measures, valid for arbitrary values of the quantum number j. We identify optimal rotosensors (i) for arbitrary rotation angles in the case of spin quantum numbers up to j=7/2 an…

共振非线性磁光旋转中的强度关联

Intensity correlations in resonance nonlinear magneto-optical rotation

研究了激光场通过共振原子介质时两个正交线偏振分量之间的强度关联。这些实验是在铷原子蒸气中进行的。我们观察到，在没有磁场的情况下，激光束的正交偏振分量之间的相关性是最大的。相关性的大小取决于所施加的磁场，并且随着磁场的增加，相关性的大小先减小然后增大。在相同的磁场下观察到最小的相关性和最大的旋转角。关联函数的宽度与激发态寿命成正比，与激光场的拉比频率成反比。这些结果对于改进光学磁强计和研究光场或原子自旋压缩有一定的参考价值。

Colliding-probe bi-atomic magnetometers via energy circulation: Breaking symmetry-enforced magneto-optical rotation blockade

We have developed an inelastic wave scattering based colliding-probe bi-atomic magnetometer theory. We show a propagation growth blockade in single probe based magnetic field sensing schemes, revealing the root cause of strong suppression of nonlinear magneto-optical rotation effect (NMORE) in single probe based atomic magnetometers. We further show, both experimentally and theoretically, a colliding probe bi-atomic magnetometer that lifts this NMORE blockade. The directional energy circulation in this new atomic magnetometry technique results in more than two orders of magnitude increase in N…

Probing vacuum-induced coherence via magneto-optical rotation in molecular systems

We investigate theoretically the effects of vacuum-induced coherence (VIC) on magneto-optical rotation (MOR). We carry out a model study to show that VIC in the presence of a control laser and a magnetic field can lead to large enhancement in the rotation of the plane of polarization of a linearly polarized weak laser with vanishing circular dichroism. This effect can be realized in cold molecular gases and may be used as a sensitive probe for VIC. Such a large MOR angle can also be used to detect weak magnetic field with large measurement sensitivity.

通过塞曼分裂能级的磁输运中的相干效应

Coherent effects in magneto-transport through Zeeman split levels

研究了弱耦合量子点或杂质与铁磁导线的非平衡电子输运。基于速率方程的形式主义，我们推导出噪声谱的传输电流。我们表明，由于量子干涉电流的不同自旋分量之间的频谱开发一个峰值或下降的频率对应于塞曼分裂的量子点。对非相互作用电子和库仑阻塞区的电流谱结构进行了详细的分析。

短相干控制脉冲的推广：推广到任意旋转

Generalization of short coherent control pulses: extension to arbitrary rotations

我们将小量子系统的相干控制问题推广到量子比特（qubit）服从完全广义旋转的情况。根据Pasini等人（2008 Phys.Rev.A77，032315）中提出的想法，脉冲短暂性的系统扩展到脉冲作用于量子位作为围绕随时间变化的旋转轴的一般旋转的情况。计算前导和下一前导校正。对于某些脉冲，我们证明了一般的旋转并没有改善简单的旋转与固定轴。

非线性磁光和自偏振态叠加旋转

Non-linear magneto-optic and self polarization rotation by superposition of states

我们报道了在原子样品中建立不同超精细态的相干叠加时，磁光旋转增强的观测结果。双光子拉曼共振条件附近的偏振旋转似乎有一个类似的特性，在一个单光子共振附近观察到的良好建立的法拉第旋转，但它包含了尖锐的功能所产生的相干布居捕获状态。双光子旋转信号的轮廓表现出有趣的功能略有不平衡的圆偏振分量的激光场，以及对和远离单光子共振。该研究可用于探讨相干布居俘获产生的叠加态对旋光性的影响。一个完整的密度矩阵为基础的数值模拟，始终捕捉所有相关的功能的实验。

Magneto-optical properties of paramagnetic superrotors

We study the dynamics of paramagnetic molecular superrotors in an external magnetic field. Optical centrifuge is used to create dense ensembles of oxygen molecules in ultra-high rotational states. It is shown for the first time, that the gas of rotating molecules becomes optically birefringent in the presence of magnetic field. The discovered effect of "magneto-rotational birefringence" indicates preferential alignment of molecular axes along the field direction. We provide an intuitive qualitative model, in which the influence of the applied magnetic field on the molecular orientation is medi…

在相干控制的原子介质中使用结构光磁力计

Structured-Light Magnetometry in a Coherently Controlled Atomic Medium

本文提出利用结构光检测磁光旋转的方法，通过将偏振旋转映射到可直接观测的空间自由度，实现基于拓扑的空间读出磁力计。

Coherent Control of the Rotational Degree of Freedom of a Two-Ion Coulomb Crystal

We demonstrate the preparation and coherent control of the angular momentum state of a two-ion crystal. The ions are prepared with an average angular momentum of $7780\hbar$ freely rotating at 100~kHz in a circularly symmetric potential, allowing us to address rotational sidebands. By coherently exciting these motional sidebands, we create superpositions of states separated by up to four angular momentum quanta. Ramsey experiments show the expected dephasing of the superposition which is dependent on the number of quanta separating the states. These results demonstrate coherent control of a co…

Magneto optical rotation in a GaAs Quantum Well Waveguide

The interaction of two orthogonally polarized beams and a four-level GaAs quantum well (QW) waveguide is investigated. It is shown that, by applying a static magnetic field normal to the propagation direction of the driving beams, the birefringence can be induced in the QW waveguide. Moreover, it is demonstrated that the dephasing rate between two ground states of the QW waveguide makes it a dichromatic medium and can also diminish the induced birefringence. Our results show how a large and complete magneto-optical rotation in the QW waveguide can be obtained via adjusting the intensity of the…

Nonlinear optical magnetometry with accessible in situ optical squeezing

We demonstrate compact and accessible squeezed-light magnetometry using four-wave mixing in a single hot rubidium vapor cell. The strong intrinsic coherence of the four wave mixing process results in nonlinear magneto-optical rotation (NMOR) on each mode of a two mode relative-intensity squeezed state. This framework enables 4.7 dB of quantum noise reduction while the opposing polarization rotation signals of the probe and conjugate fields add to increase the total signal to noise ratio.

Coherent control of group index and magneto-optical anisotropy in a multilevel atomic vapor

We study electromagnetically induced transparency (EIT) in a heated potassium vapor cell, using a simple optical setup with a single free-running diode laser and an acousto-optic modulator. Despite the fact that the Doppler width is comparable to the ground state hyperfine splitting, transparency windows with deeply sub-natural line widths and large group indices are obtained. A longitudinal magnetic field is used to split the EIT feature and induce magnetooptical anisotropy. Using the beat note between co-propagating coupling and probe beams, we perform a heterodyne measurement of the circula…