Experimental studies of light propagation and storage
H. Gao, M. Rosenberry, J. Wang, H. Batelaan
本文报道了在不同脉冲宽度、不同磁场和不同原子密度条件下，两种不同同位素的光脉冲在Rb原子蒸气中的传播和存储的实验研究。并与以往的研究结果进行了分析和比较。
We report on an experimental study of light pulse propagation and storage in a Rb atomic vapor for different pulse durations, magnetic fields, and atomic densities, and for two different isotopes. The results have been analyzed and compared with previous studies.
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Influence of relaxation on propagation, storage and retrieving of light pulses in electromagnetically induced transparency medium
通过求解麦克斯韦方程组和密度矩阵方程组的非绝热一阶自洽方程组，得到了探测脉冲传输的解析解。分析了有效蓄光的条件。得到了光传输距离的必要条件。
We consider the slow light propagation in an atomic medium with a tripod level scheme. We show that the coexistence of two types of dark-state polaritons leads to the propagation dynamics, which is qualitatively different from that in a $Λ$-medium, and allows therefore for very efficient conversion of signal photons into spin excitations. This efficiency is shown to be very close to 1 even for very long signal light pulses, which could not be entirely compressed into a Lambda-medium at a comparable strength of the control field.
Storage and perpendicular retrieving of two-dimensional pulses in electromagnetically induced transparency media
本文分析了二维脉冲在电磁感应透明介质中垂直存储和提取脉冲时的传播。已经表明，在光学厚介质中的脉冲的传播控制可以用于产生脉冲的时间形状和强度轮廓分布之间的互换。得到了反演新场的一个简单明了的解析解。
We theoretically study the propagation and storage of a classical field in a $Λ$-type atomic medium using coherent population oscillations (CPOs). We show that the propagation eigenmodes strongly relate to the different CPO modes of the system. Light storage in such modes is discussed by introducing a "populariton" quantity, a mixture of populations and field, by analogy to the dark state polariton used in the context of electromagnetically induced transparency light storage protocol. As experimentally shown, this memory relies on populations and is then - by contrast with usual Raman coherenc…
We report slowed propagation and storage and retrieval of thermal light in warm rubidium vapor using the effect of electromagnetically-induced transparency (EIT). We first demonstrate slowed-propagation of the probe thermal light beam through an EIT medium by measuring the second-order correlation function of the light field using the Hanbury-Brown$-$Twiss interferometer. We also report an experimental study on the effect of the EIT slow-light medium on the temporal coherence of thermal light. Finally, we demonstrate the storage and retrieval of thermal light beam in the EIT medium. The direct…
Random Beam Propagation in Accelerators and Storage Rings
导出了经典作用量、动量和密度定值时的联合概率分布的动力学方程。进而将流体力学的连续性方程和动量密度平衡方程转化为描述粒子在有效电磁场中运动的类薛定谔方程，得到了规范势的表达式。
We study the propagation and storage of a quantum field using ultra-narrow Coherent Population Oscillations (CPO) in a $Λ-$type atomic medium. The predictions for classical fields are checked experimentally in a metastable vapor at room temperature. We derive the evolution of its squeezing spectrum in the presence of a large classical pump field which enables CPO to exist. We show that the spontaneous emission of the residual population pumped into the excited state progressively destroys the quantum noise properties of the quantum field along propagation. The output quantum field therefore te…
We investigate the rephasing efficiency of sequences of phased pulses for spin echoes and light storage by electromagnetically induced transparency (EIT). We derive a simple theoretical model and show that the rephasing efficiency is very sensitive to the phases of the imperfect rephasing pulses. The obtained efficiency differs substantially for spin echoes and EIT light storage, which is due to the spatially retarded coherence phases after EIT light storage. Similar behavior is also expected for other light-storage protocols with spatial retardation or for rephasing of collective quantum stat…
We study the modification of a traditional electromagnetically induced transparency (EIT) stored light technique that includes both EIT and four-wave mixing (FWM) in an ensemble of hot Rb atoms. The standard treatment of light storage involves the coherent and reversible mapping of one photonic mode onto a collective spin coherence. It has been shown that unwanted, competing processes such as four-wave mixing are enhanced by EIT and can significantly modify the signal optical pulse propagation. We present theoretical and experimental evidence to indicate that while a Stokes field is indeed det…
Electromagnetically Induced Transparency and Light Storage in an Atomic Mott Insulator
实验研究了超冷~（87）Rb原子处于Mott绝缘态时在三维光晶格中的电磁感应透明和光存储。我们已经观察到约240毫秒的光存储时间，据我们所知，有史以来最长的超冷原子样品。利用由空间不均匀的远失谐光场引起的差分光位移，我们在原子样品上压印了“相位梯度”，从而控制了取回的光脉冲的角度重定向。
Single-photon coherent optics represents a fundamental importance for the investigation of quantum light-matter interactions. While most work has considered the interaction in the steady-state regime, here we demonstrate that a single-photon pulse shorter than any relaxation time in a medium propagates without energy loss and is consistently transformed into a zero-area pulse. A general analytical solution is found for photon passage through a cold ensemble of $Λ$-type atoms confined inside a hollow core of a single-mode photonic-crystal fiber. We use the robust far off-resonant Raman scheme t…
Storage of light in atomic vapor
我们报告了一个实验，在这个实验中，光脉冲被减速并被困在Rb原子的蒸气中，存储一段受控的时间，然后按需释放。我们通过动态地将光脉冲的群速度降低到零来实现这种光的存储，使得光的相干激发可逆地映射到Rb蒸气的集体塞曼（自旋）相干性。
Light storage, the controlled and reversible mapping of photons onto long-lived states of matter [1], enables memory capability in optical quantum networks [2-6]. Prominent storage media are warm alkali gases due to their strong optical coupling and long-lived spin states [7,8]. In a dense gas, the random atomic collisions dominate the lifetime of the spin coherence, limiting the storage time to a few milliseconds [9,10]. Here we present and experimentally demonstrate a storage scheme that is insensitive to spin-exchange collisions, thus enabling long storage times at high atomic densities. Th…
We address the propagation of a single photon pulse with two polarization components, i.e., a polarization qubit, in an inhomogeneously broadened "phaseonium" Λ-type three-level medium. We combine some of the non-trivial propagation effects characteristic for this kind of coherently prepared systems and the controlled reversible inhomogeneous broadening technique to propose several quantum information processing applications, such as a protocol for polarization qubit filtering and sieving as well as a tunable polarization beam splitter. Moreover, we show that, by imposing a spatial variation o…
We report on coherent and multi-temporal mode storage of light using the full atomic frequency comb memory scheme. The scheme involves the transfer of optical atomic excitations in Pr3+:Y2SiO5 to spin-waves in the hyperfine levels using strong single-frequency transfer pulses. Using this scheme, a total of 5 temporal modes are stored and recalled on-demand from the memory. The coherence of the storage and retrieval is characterized using a time-bin interference measurement resulting in visibilities higher than 80%, independent of the storage time. This coherent and multimode spin-wave memory i…
Stopped light with storage times greater than one second using EIT in a solid
我们报告的演示光存储的时间大于一秒的镨掺杂Y $_2$ SiO $_5$使用电磁感应透明。长的存储时间是由这种材料中超精细跃迁可能的长相干时间实现的。固态系统的使用还使得能够在探针和耦合光束反向传播的情况下操作，从而允许容易地分离两个光束。由于样品的光学厚度较低，存储效率较低，正如所讨论的，这一缺陷应易于纠正。
In this chapter, we will describe the storage and retrieval of quantum light (heralded single photons and entangled photons) in atomic ensembles in a solid state environment. We will consider ensembles of rare-earth ions embedded in dielectric crystals. We will describe the methods used to create quantum light spectrally compatible with the narrow atomic transitions, as well as possible protocols based on dipole rephasing that can be used to reversibly map the quantum light onto collective atomic excitations. We will review the experimental state of the art and describe in more detail quantum …
Frequency filtered storage of parametric fluorescence with electromagnetically induced transparency
将中心频率共振在87RbD1线上的宽带参量荧光脉冲（探测光）注入到冷原子系综中，并与相干光（控制光）耦合。由于参量下转换过程中的低增益，探测光处于高度聚束的光子对状态。通过关闭控制光，电磁感应透明窗口内的探测光被映射到原子上。当控制光被打开时，探测光被取回，并且从超聚束效应和取回光的相干时间的增加确认频率滤波存储。
Optimal light storage with full pulse shape control
我们实验证明最佳的存储和检索的任意形状的光脉冲的原子系综。通过成形辅助控制脉冲，我们获得接近基本极限的效率，并实现精确检索到任何预定的时间轮廓。我们的技术，证明在温暖的Rb蒸气，适用于广泛的系统和协议。作为一个例子，我们提出了他们的潜在应用创建光学时间仓量子比特和控制部分检索。
Controlled light storage in a double lambda system
理论上表明，光在四能级原子介质中存储后，有可能释放出不同频率的新脉冲，该过程由另一驱动光束控制。也可以存储一个脉冲并释放两个不同的脉冲，其中它们的时间间隔和高度受到控制。
Optimal control of light pulse storage and retrieval
我们实验证明了一个程序，以获得最高效率的光脉冲在原子介质中的存储和检索。该程序使用时间反转，以获得最佳的输入信号脉冲形状。实验结果在温暖的Rb蒸汽与理论预测吻合得很好，并证明了显着提高效率。这种优化过程适用于广泛的系统。
We consider adiabatic interaction of five-level atomic systems and their media with four short laser pulses under the condition of all two-photon detunings being zero. We derive analytical expressions for eigenvalues of the system's Hamiltonian and determine conditions of adiabaticity for both the atom and the medium. We analyse, in detail, the system's behaviour when the eigenvalue with non-vanishing energy is realized. As distinct from the usual dark state of a five-level system (corresponding to zero eigenvalue), which is a superposition of three states, in our case the superposition of fou…
We present two quantum memory protocols for solids: A stopped light approach based on spectral hole burning and the storage in an atomic frequency comb. These procedures are well adapted to the rare-earth ion doped crystals. We carefully clarify the critical steps of both. On one side, we show that the slowing-down due to hole-burning is sufficient to produce a complete mapping of field into the atomic system. On the other side, we explain the storage and retrieval mechanism of the Atomic Frequency Comb protocol. This two important stages are implemented experimentally in Tm$^{3+}$- doped yttr…
Instantaneous processing of "slow light": amplitude-duration control, storage, and splitting
控制场或低频相干性的非绝热变化允许在厚谐振吸收体中传播的信号场的几乎瞬时变化，其中实现电磁感应透明。这一发现被应用于信号的存储和检索，用于创建信号副本以及将该副本与原始脉冲分离而不破坏原始脉冲。
Differential Stark shift compensation for ground state $^{87}$Rb atoms trapped in an elliptically polarized optical lattice and "magic" magnetic field, was recently proposed and demonstrated experimentally by N. Lundblad {\it et al.}, arXiv:0912.1528 and analyzed theoretically by A. Derevianko, arXiv:0912.3233. Here we demonstrate for the first time enhanced hyperfine coherence times using the magic field technique. We observe coherent light storage with a 0.32 s lifetime in an atomic Rb gas confined in a one dimensional optical lattice and magnetic field.
Atomic Frequency Comb (AFC) protocol has been particularly successful recently to demonstrate the storage of quantum information in a solid medium (rare-earth doped crystals). The AFC is inspired by the photon-echo technique. We show in this paper that the AFC is actually closely related to the slow-light based storage protocols extensively used in atomic vapours. Experimental verifications are performed in thulium doped YAG (Tm3+:YAG). We clarify the interplay between absorption and dispersion and propose a classification of the existing protocols.
The deployment of a fully-fledged quantum internet poses the challenge of finding adequate building-blocks for entanglement distribution between remote quantum nodes. An ideal system would combine propagation in optical fibres with quantum memories for light, leveraging on the existing communication network while featuring the scalability required to extend to network sizes. Here we demonstrate a fiber-integrated quantum memory entangled with a photon at telecommunication wavelength. The storage device is based on a fiber-pigtailed laser written waveguide in a rare-earth doped solid and allows…
Light Qubit Storage and Retrieval using Macroscopic Atomic Ensembles
我们提出了一个实验上可行的协议，在原子量子存储器中的任意光态的完全存储和检索使用良好的法拉第光与物质之间的相互作用。我们的协议依赖于一个单一的光脉冲通过原子系综的多个通道，而没有不切实际的要求公里长的延迟线之间的通道。此外，我们引入了一个依赖于时间的相互作用强度，使存储和检索的状态与任意脉冲形状。在没有压缩或纠缠初态的情况下，保真度指数地接近单位，如光子量子比特的显式计算所示。
Limitations of light delay and storage times in EIT experiments with condensates
我们研究了EIT实验中原子碰撞对探测脉冲存储和延迟时间的限制。我们发现，原子碰撞可以描述一个有效的衰减率，限制存储和延迟时间。我们计算的动量和温度依赖的衰变率，并发现它是必要的，以特定的动量取决于温度和间距的能级参与，以尽量减少原子碰撞的退相干效应。
We present a light-storage experiment in a praseodymium-doped crystal where the light is mapped onto an inhomogeneously broadened optical transition shaped into an atomic frequency comb. After absorption of the light the optical excitation is converted into a spin-wave excitation by a control pulse. A second control pulse reads the memory (on-demand) by reconverting the spin-wave excitation to an optical one, where the comb structure causes a photon-echo type rephasing of the dipole moments and directional retrieval of the light. This combination of photon echo and spin-wave storage allows us …
Quantum storage and cloning of light states in EIT-like medium
本文研究了在电磁感应透明（EIT）效应存在下，利用三能级原子（分子）系统存储和克隆量子信息的新方法。为此，提出了介质中光场量子态转化为亮、暗极化激元的各种方案。首次提出了实现量子光态的量子非破坏存储的物理条件。我们证明了原子系综处于玻色-爱因斯坦凝聚态时，能获得最佳的存储和克隆。我们讨论了受激拉曼双色光缔合实验实现的计划正在考虑中。
We investigate several recently published benchmark criteria for storage or transmission of continuous-variable quantum information. A comparison reveals that criteria based on a Gaussian distribution of coherent states are most resilient to noise. We then address the issue of experimental resources and derive an equally strong benchmark, solely based on three coherent states and homodyne detection. This benchmark is further simplified in the presence of naturally occurring random phases, which remove the need for active input-state modulation.
Image Storage in Hot Vapors
我们从理论上研究了热原子蒸气中图像的传输和存储。采用$4f$系统进行成像，并将原子蒸气室放置在变换平面上。根据“光存储”的思想，物体在物平面上的夫琅禾费衍射图样可以转换为原子拉曼相干。我们研究如何存储的衍射图案下扩散的演变。我们的结果表明，在适当的条件下，图像可以重建高保真度。这个过程工作的主要原因是衍射图案的反相分量的扩散相消干涉的事实。
Efficient and long-lived interfaces between light and matter are crucial for the development of quantum information technologies. Integrated photonics solutions for quantum storage devices offer improved performances due to light confinement and enable more complex and scalable designs. We demonstrate a novel platform for quantum light storage based on laser written waveguides. The new writing regime adopted allows us to attain waveguides with improved confining capabilities compared to previous demonstrations. We report the first demonstration of single photon storage in laser written wavegui…
Storage of light: A useful concept?
我们分析和数值计算表明，从探测脉冲的光子不存储在最近的几个实验。相反，它们被吸收以产生双光子激发。更重要的是，当一个相同的耦合脉冲被重新注入到介质中，我们表明，再生的光场的脉冲宽度是非常不同的，从原来的探测场。因此，它不是原始探测脉冲的忠实副本。
Storage and retrieval of nonclassical photon pairs and conditional single photons generated by parametric down-conversion process
存储和检索的参数下转换（PDC）光子的电磁感应透明（EIT）证明。对宽带PDC光的THz级进行了极频滤波，使光的频率带宽降低到MHz级。存储和检索程序进行频率滤波的PDC光子。由于滤波带宽[半高全宽（FWHM）= 9MHz]在EIT窗口（FWHM = 12.6MHz）内，因此成功地存储和检索PDC光的通量。利用光子计数方法证明了恢复光的非经典性，并引入了仅对经典光场满足的经典不等式。由于PDC光子可以有条件地用于产生单光子态，因此也对有条件的单光子执行存储和检索过程。用于检验单光子态性质的反相关参数值小于1，表明所提取的光处于非经典区域。
We experimentally demonstrate storage and on-demand release of phase-sensitive, photon-number superposition states of the form $α|0\rangle + βe^{iθ} |1\rangle$ for an optical quantized oscillator mode. For this purpose, we introduce a phase-probing mechanism to a storage system composed of two concatenated optical cavities, which was previously employed for storage of phase-insensitive single-photon states [Phys. Rev. X 3, 041028 (2013)]. This is the first demonstration of all-optically storing highly nonclassical and phase-sensitive quantum states of light. The strong nonclassicality of the s…
Storage and Retrieval of a Squeezed Vacuum
利用电磁感应透明性成功地证明了压缩真空的存储和恢复。利用强控制光，将930 ns的压缩真空脉冲以相干态入射到激光冷却的~（87）Rb原子上。当压缩真空脉冲在冷原子中被减速和空间压缩时，控制光被关闭。在3us的存储之后，再次打开控制光并且恢复压缩真空，如使用时域零差方法所确认的。
We demonstrate efficient and reversible mapping of a light field onto a thulium-doped crystal using an atomic frequency comb (AFC). Thanks to an accurate spectral preparation of the sample, we reach an efficiency of 9%. Our interpretation of the data is based on an original spectral analysis of the AFC. By independently measuring the absorption spectrum, we show that the efficiency is both limited by the available optical thickness and the preparation procedure at large absorption depth for a given bandwidth. The experiment is repeated with less than one photon per pulse and single photon coun…
Tapered optical fibers with a nanofiber waist are versatile tools for interfacing light and matter. In this context, laser-cooled atoms trapped in the evanescent field surrounding the optical nanofiber are of particular interest: They exhibit both long ground-state coherence times and efficient coupling to fiber-guided fields. Here, we demonstrate electromagnetically induced transparency, slow light, and the storage of fiber-guided optical pulses in an ensemble of cold atoms trapped in a nanofiber-based optical lattice. We measure a slow-down of light pulses to group velocities of 50 m/s. More…
We propose a quantum memory protocol based on dynamically changing the resonance frequency of an ensemble of two-level atoms. By sweeping the atomic frequency in an adiabatic fashion, photons are reversibly transferred into atomic coherences. We present a polaritonic description for this type of storage, which shares some similarities with Electromagnetically Induced Transparency (EIT) based quantum memories. On the other hand the proposed memory is also linked to the Gradient Echo Memory (GEM) due to the effective spatial gradient that pulses experience in the medium. We discuss a possible im…
Universal Approach to Optimal Photon Storage in Atomic Media
本文提出了一个描述光子波包在λ型原子介质中存储和恢复的普适物理图象。这张物理图片涵盖了各种不同的方法来脉冲存储，从绝热减少的光子群速度和脉冲传播控制通过非共振拉曼场光子回波为基础的技术。此外，我们推导出一个最佳的控制策略的存储和检索的光子波包的任何给定的形状。所有这些方法在优化时产生相同的最大效率，其仅取决于介质的光学深度。
Optimal light storage in atomic vapor
我们研究的程序的光存储和检索的基础上的动态形式的电磁感应透明（EIT）在温暖的Rb蒸汽的效率的优化。我们提出了一个详细的分析，最近证明的两个优化协议：基于时间反演的迭代过程，它找到了最佳的输入信号脉冲形状为任何给定的控制字段，和一个程序的基础上计算的最佳控制字段为任何给定的信号脉冲形状。我们验证了这两个程序是相互一致的，并且它们都独立地实现了任何给定的光学深度的最大存储效率。我们观察到与中等光学深度（<25）的理论预测很好的一致性，而在较高的光学深度的实验效率低于理论预测值。我们确定可能的影响负责这种内存效率的降低。
Storage and retrieval of light pulses in atomic media with "slow" and "fast" light
我们提出的实验证据表明，光存储，即由原子样品的光脉冲的控制释放依赖于过去存在的写入脉冲，不限于小群速度介质，但也可以发生在负群速度介质。一个简单的物理图片适用于这两种情况和以前的光存储实验进行了讨论。
We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the…
Conditional detection is an important tool to extract weak signals from a noisy background and is closely linked to heralding, which is an essential component of protocols for long distance quantum communication and distributed quantum information processing in quantum networks. Here we demonstrate the conditional detection of time-bin qubits after storage in and retrieval from a photon-echo based waveguide quantum memory. Each qubit is encoded into one member of a photon-pair produced via spontaneous parametric down conversion, and the conditioning is achieved by the detection of the other me…
Enhancing capacity of coherent optical information storage and transfer in a Bose-Einstein condensate
研究了原子玻色-爱因斯坦凝聚体的相干光信息存储能力。通过考虑群速度色散，将原子云中的慢光传输理论推广到短脉冲区域。结果表明，在特定的耦合激光功率，温度和原子间相互作用强度的凝聚体中的存储脉冲的数量可以进行优化。采用有效均匀密度区近似，对半理想模型的凝结体进行了解析计算。还进行了详细的数值模拟。研究发现，凝结体的轴向密度分布可以保护脉冲不受群速度色散的影响。此外，考虑到凝聚体的有限径向尺寸，研究了多模光在原子玻色-爱因斯坦凝聚体中的传输。得到了凝聚体所能支持的模数，并确定了单模条件与实验参数的函数关系，这些参数包括阱尺寸、温度、凝聚体数密度和散射长度。提出了一种增强多模光传输效应的量子相干原子-光相互作用方案。
Steep optical wave group velocity reduction and storage of light without electromagnetically induced transparency
本文报道了利用喇曼方案降低光脉冲群速度和探测脉冲再生的实验研究。新方案不依赖于单光子共振电磁感应透明（EIT），与传统的依赖于EIT过程产生的透明窗口的方法相比具有许多优点。我们证明了显着降低群速度，探测场损失少，减少探测脉冲失真，和高探测脉冲再生效率。
Slow light propagation in trapped atomic quantum gases
研究了半经典慢光在囚禁二能级原子量子气体中的传输。在局域密度近似下，比较了低温玻色、费米和玻尔兹曼气体的群速度和透射率随温度的变化规律.
An implementation is proposed of single qubit gates, e.g., phase, NOT, \sqrt{NOT} and Hadamard, operating on polarized photons and based on light storage. Instead of processing photons themselves, qubit transformations are performed on atomic excitations due to photon storage in a medium of atoms in the tripod configuration.
We report on the first observation of stationary light pulses and narrowband light storage inside a hollow-core photonic crystal fiber. Laser-cooled atoms were first loaded into the fiber core providing strong light-matter coupling. Light pulses were then stored in a collective atomic excitation using a single control laser beam. By applying a second counterpropagating control beam, a light pulse could be brought to a standstill. Our work paves the way towards the creation of strongly-correlated many-body systems with photons and applications in the field of quantum information processing.
We demonstrate the storage of $5$ ns light pulses in a single rubidium atom coupled to a fiber-based optical resonator. Our storage protocol addresses a regime beyond the conventional adiabatic limit and approaches the theoretical bandwidth limit. We extract the optimal control laser pulse properties from a numerical simulation of our system and measure storage efficiencies of $(8.2\pm 0.6)~\%$, in close agreement with the maximum expected efficiency. Such well-controlled and high-bandwidth atom-photon interfaces are key components for future hybrid quantum networks.
Photon-echo based optical quantum memory schemes often employ intermediate steps to transform optical coherences to spin coherences for longer storage times. We analyze a scheme that uses three identical chirped control pulses for coherence rephasing in an inhomogeneously broadened ensemble of three-level $Λ$-systems. The pulses induce a cyclic permutation of the atomic populations in the adiabatic regime. Optical coherences created by a signal pulse are stored as spin coherences at an intermediate time interval, and are rephased for echo emission when the ensemble is returned to the initial s…
Here we demonstrate generating and storing entanglement in a solid state spin-wave quantum memory with on-demand read out using the process of rephased amplified spontaneous emission (RASE). Amplified spontaneous emission (ASE), resulting from an inverted ensemble of Pr$^{3+}$ ions doped into a Y$_2$SiO$_5$ crystal, generates entanglement between collective states of the praseodymium ensemble and the output light. The ensemble is then rephased using a four-level photon echo technique. Entanglement between the ASE and its echo is confirmed and the inseparability violation preserved when the RAS…
A Knob for Changing Light Propagation from Subluminal to Superluminal
我们展示了如何应用一个耦合场连接两个较低的亚稳态的双稳态系统可以产生各种新的结果对弱电磁脉冲的传播。原则上，光的传播可以从亚光速变为超光速。负群指数是由反常色散和磁化率增益区域引起的。
Comparative study of light storage in antirelaxation-coated and buffer-gas-filled alkali vapor cells
本研究比较了抗弛豫涂层与缓冲气体填充碱金属蒸气池中的光存储，发现缓冲气体填充池在存储时间和效率上提升约10倍，为高性能量子存储器的发展提供支持。
Controlled manipulation, storage and retrieval of quantum information is essential for quantum communication and computing. Quantum memories for light, realized with cold atomic samples as the storage medium, are prominent for their high storage efficiencies and lifetime. We demonstrate the controlled transport of stored light over 1:2 mm in such a storage system and show that the transport process and its dynamics only have a minor effect on the coherence of the storage. Extending the presented concept to longer transport distances and augmenting the number of storage sections will allow for …
We propose a new method to create two-photon states in a controllable way using interaction between the Rydberg atoms during the storage and retrieval of slow light. A distinctive feature of the suggested procedure is that the slow light is stored into a superposition of two atomic coherences under conditions of electromagnetically induced transparency (EIT). Interaction between the atoms during the storage period creates entangled pairs of atoms in a superposition state that is orthogonal to the initially stored state. Restoring the slow light from this new atomic state one can produce a two …
We study the propagation of quantum states of light in separable longitudinally inhomogeneous media. By means of the usual quantization approach this kind of media would lead to the unphysical result of quantum noise squeezing. This problem is solved by means of generalized canonical transformations in a comoving frame. Under these transformations the generator of propagation is a physical Lewis-Ermakov invariant in space which is quantized and, accordingly, a propagator consistent with experiments is obtained. Finally, we show that the net effect produced by propagation in these media is a qu…
Absorption free superluminal light propagation in a three level pump-probe system
研究了三能级抽运-探测原子系统中弱探测光场的色散和吸收特性。结果表明，色散斜率随相干或间接非相干泵浦光强度的变化而从正变到负。结果表明，在该系统中出现了无吸收的超光速光传播。
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