Name: generation and coherent control of pulsed quantum frequency combs
Uploaded: 2018-06-08T13:00:00
Description: Watch this Scientific Journal Video about Generation and Coherent Control of Pulsed Quantum Frequency Combs at JoVE.com

我们感谢 r. Helsten 的技术洞察力;p 从 QPS Photronics 的帮助和加工设备;以及 QuantumOpus 和 n 贝尔托光电元件的支持和为我们提供最先进的光子检测设备。这项工作是由下列资金来源作出的: 加拿大自然科学和工程研究理事会 (NSERC) (Steacie、战略、发现和加速赠款计划、Vanier 加拿大研究生奖学金、USRA 奖学金);Mitacs (IT06530) 和 PBEEE (207748);MESI SIIRI 倡议;加拿大研究椅项目;澳大利亚研究委员会发现项目 (DP150104327);欧洲联盟的地平线2020在玛丽玛丽·斯卡洛多斯卡·居里-居里赠款下的研究和创新计划 (656607);(城大 SRG-Fd 计划 (7004189);中国科学院战略优先研究项目 (XDB24030300);欧洲联盟 FP7 方案 INCIPIT (PIOF-GA-2013-625466) 下的《人民方案》 (居里夫人行动);俄罗斯联邦政府通过 ITMO 研究金和教授方案 (赠款 074-U 01);1000人才四川项目 (中国)

1. 通过脉冲激发产生高维频率-bin 纠缠态
<ol><li>按照图 2 (生成阶段) 中概述的方案, 使用偏振维护光纤连接每个组件 (以改善环境稳定性)。</li>
	<li>将电源连接到电光振幅调制器, 并应用直流电压偏移, 调整偏移值, 直到通过它传输的光功率大约减半 (使用光功率计测量), 如峰值2兆瓦的传输值被减半到1兆瓦。</li>
	<li>测量近似的外腔长度。使用关系计算外部腔模式间距,<...

<ol>
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光频域, 通过 QFCs, 在量子应用中是有利的, 原因很多。操作是全局的, 同时对所有状态执行, 这会导致在状态维度增加时不会扩展大小或复杂性的设计。随着组件可以在不改变安装的情况下进行重新配置, 并且能够通过开发现有的和/或开发的半导体和电信基础设施集成到芯片上, 这一点得到了加强。其他光学微腔的生成技术也可以采用, 如二阶非线性微腔28、微盘<sup class="xref...

量子现象的控制为在安全量子通信1、强大的量子信息处理2和量子传感3等不同领域的新应用开辟了可能性。虽然各种物理平台正在积极研究实现量子技术4, 光量子态是重要的候选, 因为它们可以表现出长期的相干时间和稳定性从外部噪音, 优秀传输特性, 以及与现有通信和硅片 (CMOS) 技术的兼容性。
为了充分实现量子技术中光子的潜能, 通过使用多个纠缠方和/或高维度, 可以提高状态复杂性和信息内容。然而, 这种光学状态的芯片生成缺乏实用性, 因为设置是复杂的, 不是完全可伸缩的, 和/或使用高度专门化的组件。具体来说, 高维路径纠缠需要<img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">一致激发的相同源和复杂的光束分配器5 ( <img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">状态维度) 电路, 而时间纠缠需要复杂的多臂干涉仪6。值得注意的是, 频域非常适合于复杂状态的可伸缩生成和控制, 如最近在量子频率梳 (QFC)7,8中利用集成光学和电信基础设施9, 为未来的量子信息技术提供了一个有希望的框架。
在集成微腔中利用非线性光学效应产生了片上 QFCs。使用这样一个非线性微谐振器, 两个纠缠光子 (称为信号和滚轮) 是由自发的四波混合产生, 通过湮灭两个励磁光子-与产生的一对叠加的腔的结果对均匀间隔的谐振频率模式 (图 1)。如果单个频率模式之间存在一致性, 则形成10的频率-bin 纠缠态, 通常称为锁模两光子状态11。这个状态波函数可以描述,
<img alt="Equation 02" src="/files/ftp_upload/57517/57517eq02v3.jpg">
在这里<img alt="Equation 03" src="/files/ftp_upload/57517/57517eq03v3.jpg"> , <img alt="Equation 04" src="/files/ftp_upload/57517/57517eq04v3.jpg">分别是单频模式的滚轮和信号分量, 并且<img alt="Equation 05" src="/files/ftp_upload/57517/57517eq05v3.jpg">是 th 信号-滚轮模式对的概率<img alt="Equation 06" src="/files/ftp_upload/57517/57517eq06v3.jpg">振幅。
以前的芯片 QFCs 演示强调了它们作为可行的量子信息平台的通用性, 包括相关光子12、交叉极化光子13、纠缠光子14、15的梳子。,16、多光子状态15、频率-bin 纠缠态9、17。在这里, 我们提供了一个详细的概述 QFC 平台和一个协议的高维频率-bin 纠缠光学状态产生和控制。
未来的量子应用, 特别是那些与高速电子接口 (为了及时信息处理), 要求高纯度的光子状态的高速度生成在紧凑和稳定的设置。我们使用一个主动锁模, 嵌套腔方案, 以产生 QFCs 在电信, C 和 L 频段。微环被并入一个较大的脉冲激光腔内, 光增益 (由掺铒光纤放大器提供) 过滤, 以匹配微环励磁带宽18。锁模是通过对腔体损耗19的电光调制来积极实现的。隔离器确保脉冲传播跟随一个方向。所产生的脉冲列车具有很低的根平均平方 (RMS) 噪声, 并具有可调谐的重复率和脉冲功率。高隔离陷波滤波器将发射的 QFC 光子与励磁场分离开来。这些单光子然后引导通过纤维进行控制和检测。
我们的计划是迈向高世代率, 小脚印 QFC 源, 因为所有使用的组件可能会集成到一个光子芯片上。此外, 脉冲激励特别适合量子应用。首先, 看一双与励磁对称的微谐振腔共振, 它产生双光子状态, 每个光子的特征为线性光量子计算20的单频 mode–中心。同样, 多光子状态可以通过移动到更高的功率激励机制和选择多个信号-滚轮对15来产生。第二, 光子在已知的时间窗口中发出, 对应于脉冲励磁, 可以实现后处理和门控, 以改善状态检测。也许最重要的是, 我们的方案支持使用谐波锁模锁定的高频率光子状态, 而不降低巧合-意外比 (汽车)-这可能为高速、多通道量子信息铺平道路。技术。
为了证明频率域的影响和可行性, 必须以有针对性的方式实现对 QFC 状态的控制, 确保高效的转换和状态一致性。为了满足这些要求, 我们使用级联可编程滤波器和相位调制器-在电信行业中建立的组件。可编程滤波器用于在单光子上施加任意的光谱振幅和相位掩码, 分辨率足以单独处理每个频率模式;射频信号发生器驱动的电光相位调制器促进了频率元件21的混合。
该控制方案最重要的方面是, 它使用单一的控制元素, 同时在单一空间模式下对光子的所有量子模式进行操作。增加量子态维度不会导致安装复杂度的增加, 与路径或时间 bin 纠缠方案形成对比。而且, 所有组件都是外部可重构的 (这意味着可以在不修改设置的情况下更改操作) 并使用现有的电信基础结构。因此, 在超快光学处理领域的现有和即将发展可以直接转移到量子态的可伸缩控制的未来。
总之, QFCs 的利用频率域支持复杂量子态的高速率生成及其控制, 因此非常适合于利用复杂的国家实现实用和可伸缩的量子技术。

<table>
	<tbody>
		<tr>
			<td>Superconducting Nanowire Single-Photon Detector System</td>
			<td>Quantum Opus</td>
			<td>Opus One</td>
			<td></td>
		</tr>
		<tr>
			<td>Electro-optic phase modulator</td>
			<td>EO-Space</td>
			<td>Low loss model</td>
			<td></td>
		</tr>
		<tr>
			<td>Programmable filter</td>
			<td>Finisar&#160;</td>
			<td>WaveShaper 4000s</td>
			<td></td>
		</tr>
		<tr>
			<td>Timing electronics</td>
			<td>PicoQuant</td>
			<td>HydraHarp 400</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro-ring resonator</td>
			<td></td>
			<td></td>
			<td>200 GHz FSR micro-ring resonator made from high refractive index glass. See Ref. 24 for platform details.</td>
		</tr>
		<tr>
			<td>Erbium-doped fiber amplifier</td>
			<td>Keopsys</td>
			<td>PEFA-SP-C-PM-27-B202-FA-FA</td>
			<td></td>
		</tr>
		<tr>
			<td>Electro-optic amplitude modulator</td>
			<td>Oclaro&#160;</td>
			<td>SD40</td>
			<td></td>
		</tr>
		<tr>
			<td>RF tone source</td>
			<td>Rohde &#38; Schwarz</td>
			<td>SMP 04</td>
			<td></td>
		</tr>
		<tr>
			<td>RF tone amplifier</td>
			<td>RF-Lambda</td>
			<td>RFLUPA27G34GA</td>
			<td></td>
		</tr>
		<tr>
			<td>Function generator</td>
			<td>Tetronix</td>
			<td>AFG 3251</td>
			<td></td>
		</tr>
		<tr>
			<td>Isolator</td>
			<td>General Photonics</td>
			<td>NISO-S-15-SS-FC/APF</td>
			<td></td>
		</tr>
		<tr>
			<td>Oscilloscope</td>
			<td>Tetronix&#160;</td>
			<td>TDS5052B</td>
			<td></td>
		</tr>
		<tr>
			<td>Photodiode</td>
			<td>Finisar</td>
			<td>XPDV 50 GHz</td>
			<td></td>
		</tr>
		<tr>
			<td>DWDM</td>
			<td>OptiWorks</td>
			<td>DWFUQUMD08BN</td>
			<td></td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Madell</td>
			<td>CA18303D</td>
			<td></td>
		</tr>
	</tbody>
</table>

generation and coherent control of pulsed quantum frequency combs

提出了一种脉冲量子频率梳的产生和相干操作方法。到目前为止, 由于准备和处理这些状态所需的量子电路越来越复杂, 因此在芯片上以实际方式制备高维状态的方法仍然是难以捉摸的。在这里, 我们概述了如何高维, 频率-bin 纠缠, 双光子状态可以产生在稳定的, 高的产生率, 利用嵌套腔, 主动锁模励磁的非线性微腔。该技术用于产生脉冲量子频率梳。此外, 我们还介绍了如何使用标准通信组件 (如可编程滤波器和电光调制器) 对量子态进行相干操作。具体来说, 我们详细地介绍了如何完成状态表征测量, 如密度矩阵重构, 重合检测和单光子光谱测定。所提出的方法为复杂的高维状态准备和操作协议在频域中形成了一个可访问的、可重构的、可以伸缩的基础。

图 2显示了高维频率-bin 状态的生成和控制 (基于非线性微腔的激发) 的概述方案 (图 1)。此设置使用标准电信组件, 并且在光子生产速率和处理操作应用上具有高度灵活性。图 3显示了通过重合率和汽车作为重复率函数的生成方案的特性, 证明了光子对的生产可以在不减少汽车的情况下增加。在控制部分, 可?...

Watch this Scientific Journal Video about Generation and Coherent Control of Pulsed Quantum Frequency Combs at JoVE.com

Generation and Coherent Control of Pulsed Quantum Frequency Combs

提出了一种利用集成微腔和标准通信组件对高维频率-bin 纠缠光子状态进行实际生成和相干操作的协议。

脉冲量子频率梳的产生与相干控制

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional ...

The overall goal of this protocol is to generate and coherently control pulsed quantum frequency combs which may be used for quantum information processing. This method can help us provide the tools for fundamental investigations of quantum mechanics and for realizing non-classical technologies, such as quantum communications and information processing. The main advantage of this technique is that well-established telecommunications components and protocols are used to generate and control complex optical quantum states in a reconfigurable and scalable way.We have this idea when we talk with my colleague Jose Azana who is an expert in telecommunication processing, and we realized that we could transfer these tools to the world of quantum objects. Set up the components of the system on an optical table. The system has stages for generation, control, and processing.This depiction provides an overview. All elements are connected with polarization maintaining optical fiber. For now, focus on the generation stage.This stage features an on chip micro-ring resonator embedded in a larger external cavity. The external cavity is made of an electro-optic amplitude modulator driven by a signal generator, an isolator, and an erbium-doped fiber amplifier providing optical gain. There is a narrow filter with a pass band selecting a single microcavity resonance and a notch filter routing the generated photons to the control section.With the cavity disconnected, initiate the erbium-doped fiber amplifier. Use an optical power meter after the amplitude modulator to measure the transmitted power. At the modulator, use a power supply to apply a DC offset to have the transmitted power.Reconnect the cavity and insert a fast photo diode into a different ring port. Use an oscilloscope to observe its signal in the time domain. Without the modulator activated, the output will show unstable pulse operation with a low quality pulse train.Return to the amplitude modulator and connect the function generator. Set the output frequency of the generator to a multiple of the approximate external cavity mode spacing. Selecting a rectangular or sine waveform and turn on the function generator.Tune the function generator frequency and DC offset to optimize and stabilize the pulse train on the oscilloscope. Manually adjust the gain to set the pulse intensity. The non-linear four wave mixing process inside the ring resonator now creates signal and idler photon pairs which will leave the external cavity at the notch filter.Connect the synchronization signal from the function generator to the timing electronics. The generation rate of this pulsed quantum frequency comb may be increased by driving the modulator a higher harmonics of the external cavity frequency spacing, thus entering a harmonic mode locking machine. The amplifier gain must then also be increased to ensure the same power per pulse.After the notch filter in the generation stage, the entangled photons enter the control stage. There, in order, they encounter a programmable filter, a phase modulator, and a second programmable filter. First, program the filters.Set the amplitude of the desired frequency mode channels and attenuate the others. Similarly, decide on the desired phase mask. Do this for each filter.This image represents the amplitude and phase for a coincidence measurement. To prepare the phase modulator, connect the signal generator to the RF amplifier with low loss cables. Then connect the RF amplifier to the phase modulator.Once all the RF ends are connected and terminated, bias the amplifier. Set the RF signal generator to create sidebands which overlap with the desired frequency modes, then turn it on. As a test, set up the system to send a continuous wave laser beam through the phase modulator.Use an optical spectrum analyzer to check that the input spectrum produces an output spectrum that corresponds to the intended modulation for the experiment. To continue, connect the phase modulator with the programmable filters. When setting the phase modulation pattern, it is important to determine what pattern will create the targeted frequency sidebands for the chosen operation.This will depend on the dimension of the quantum state used and on microcavity resonance spacing. The photon pairs from the generation stage enter the control stage. The first filter sets the programmed amplitude and phase.Next, the phase modulator creates the necessary frequency sidebands. The second filter selects the signal and idler pair. On input to the processing stage, separate the entangled photons with a dense wavelength division multiplexer.From there, they each go to single photon detectors. Record the arrival time of each photon using timing electronics set up for coincidence measurement. The setup allows coherent control over the photon states.Here frequency sidebands are generated via phase modulation. The sideband spacing and amplitudes are determined by the modulating signal. Coherent control of the photon state can be used for quantum state tomography.This is an example reconstruction of the state density matrix for a two photon system with a dimensionality of three for each photon. The fidelity between the measured and maximally entangled states is about 81%The pulsed high repetition rate generation technique is not limited to micro-ring resonators and may be adopted for other optical cavities, such as photonic crystal waveguides, microdisks, and second-order nonlinear cavities. With its development, the platform combines established techniques in telecommunications with quantum technologies towards potential applications, like secure communications at high rates over multiplex channels or high-dimensional quantum operations.

generation-and-coherent-control-of-pulsed-quantum-frequency-combs

Research

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Electrical Engineering

Engineering

Unit 1

Frequency Response

SCIENTISTS IN ACTION

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

制备纳米设计的脉冲激光沉积透明导电氧化物

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

科研

工程学

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.

The gradient echo memory is a protocol for storing optical quantum states of light in atomic ensembles. Quantum memory is a key element of a quantum repeater, which can extend the range of quantum key distribution. We outline the operation of the scheme when implemented in a 3-level atomic ensemble.

梯度回波量子存储在温暖的原子蒸气

Gradient  echo memory (GEM) is a protocol for storing optical quantum states of light in  atomic ensembles. The primary motivation for such a technology ...

Nanofabrication of Gate-defined GaAs/AlGaAs Lateral Quantum Dots

A quantum computer is a computer composed of quantum bits (qubits) that takes advantage of quantum effects, such as superposition of states and entanglement, to solve certain problems exponentially faster than with the best known algorithms on a classical computer. Gate-defined lateral quantum dots on GaAs/AlGaAs are one of many avenues explored for the implementation of a qubit. When properly fabricated, such a device is able to trap a small number of electrons in a certain region of space. The spin states of these electrons can then be used to implement the logical 0 and 1 of the quantum bit. Given the nanometer scale of these quantum dots, cleanroom facilities offering specialized equipment- such as scanning electron microscopes and e-beam evaporators- are required for their fabrication. Great care must be taken throughout the fabrication process to maintain cleanliness of the sample surface and to avoid damaging the fragile gates of the structure. This paper presents the detailed fabrication protocol of gate-defined lateral quantum dots from the wafer to a working device. Characterization methods and representative results are also briefly discussed. Although this paper concentrates on double quantum dots, the fabrication process remains the same for single or triple dots or even arrays of quantum dots. Moreover, the protocol can be adapted to fabricate lateral quantum dots on other substrates, such as Si/SiGe.

This paper presents a detailed fabrication protocol for gate-defined semiconductor lateral quantum dots on gallium arsenide heterostructures. These nanoscale devices are used to trap few electrons for use as quantum bits in quantum information processing or for other mesoscopic experiments such as coherent conductance measurements.

纳米加工门定义的GaAs / AlGaAs多量子点横向

A quantum computer is a computer composed of quantum bits (qubits) that takes advantage of quantum effects, such as superposition of states and ...

Analysis of Contact Interfaces for Single GaN Nanowire Devices

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit a strong degradation after annealing due to the occurrence of void formation at the contact/SiO2 interface. This void formation can cause cracking and delamination of the metal film, which can increase the resistance or lead to a complete failure of the NW device. In order to address issues associated with void formation, a technique was developed that removes Ni/Au contact metal films from the substrates to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN NW devices. This procedure determines the degree of adhesion of the contact films to the substrate and NWs and allows for the characterization of the morphology and composition of the contact interface with the substrate and nanowires. This technique is also useful for assessing the amount of residual contamination that remains from the NW suspension and from photolithographic processes on the NW-SiO2 surface prior to metal deposition. The detailed steps of this procedure are presented for the removal of annealed Ni/Au contacts to Mg-doped GaN NWs on a SiO2 substrate.

A technique was developed that removes Ni/Au contact metal films from their substrate to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN nanowire devices.

单氮化镓纳米线设备分析接触界面

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit  a strong degradation after annealing due to the  occurrence of void formation at the ...

Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

This is an instructional paper to guide the construction and diagnostics of external cavity diode lasers (ECDLs), including component selection and optical alignment, as well as the basics of frequency reference spectroscopy and laser linewidth measurements for applications in the field of atomic physics.

外腔半导体激光器的原子物理的构建与鉴定

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and ...

Coherent anti-Stokes Raman Scattering (CARS) Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and structure can change during dissolution, it is essential to monitor it during dissolution testing. In this work coherent anti-Stokes Raman scattering microscopy is used to image the surface of tablets during dissolution while UV absorption spectroscopy is simultaneously providing inline analysis of dissolved drug concentration for tablets containing a 50% mixture of theophylline anhydrate and ethyl cellulose. The measurements showed that in situ CARS microscopy is capable of imaging selectively theophylline in the presence of ethyl cellulose. Additionally, the theophylline anhydrate converted to theophylline monohydrate during dissolution, with needle-shaped crystals growing on the tablet surface during dissolution. The conversion of theophylline anhydrate to monohydrate, combined with reduced exposure of the drug to the flowing dissolution medium resulted in decreased dissolution rates. Our results show that in situ CARS microscopy combined with inline UV absorption spectroscopy is capable of monitoring pharmaceutical tablet dissolution and correlating surface changes with changes in dissolution rate.

Coherent anti-Stokes Raman Scattering CARS Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with an intrinsic flow-through dissolution setup to allow in situ and real-time visualization of the surface of pharmaceutical tablets undergoing dissolution. Using this custom-built setup, it is possible to correlate CARS videos with drug dissolution profiles recorded using inline UV absorption spectroscopy.

相干反斯托克斯拉曼散射（CARS）显微可视化药片剂溶出过程中

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Silicon Metal-oxide-semiconductor Quantum Dots for Single-electron Pumping

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by quantum mechanical effects such as tunneling through single dopants, scattering via interface defects, and discrete trap charge states. However, progress in silicon technology has shown that these phenomena can be harnessed and exploited for a new class of quantum-based electronics. Among others, multi-layer-gated silicon metal-oxide-semiconductor (MOS) technology can be used to control single charge or spin confined in electrostatically-defined quantum dots (QD). These QD-based devices are an excellent platform for quantum computing applications and, recently, it has been demonstrated that they can also be used as single-electron pumps, which are accurate sources of quantized current for metrological purposes. Here, we discuss in detail the fabrication protocol for silicon MOS QDs which is relevant to both quantum computing and quantum metrology applications. Moreover, we describe characterization methods to test the integrity of the devices after fabrication. Finally, we give a brief description of the measurement set-up used for charge pumping experiments and show representative results of electric current quantization.

The fabrication process and experimental characterization techniques relevant to single-electron pumps based on silicon metal-oxide-semiconductor quantum dots are discussed.

硅金属 - 氧化物 - 半导体量子点单电子泵

As mass-produced silicon transistors have reached the nano-scale, their behavior and performances are increasingly affected, and often deteriorated, by ...

Study of Siphon Breaker Experiment and Simulation for a Research Reactor

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent this outflow, a control device is required. A siphon breaker is a type of safety device that can be utilized to control the loss of coolant water effectively.
To analyze the characteristics of siphon breaking, a real-scale experiment was conducted. From the results of the experiment, it was found that there are several design factors that affect the siphon breaking phenomenon. Therefore, there is a need to develop a theoretical model capable of predicting and analyzing the siphon breaking phenomenon under various design conditions. Using the experimental data, it was possible to formulate a theoretical model that accurately predicts the progress and the result of the siphon breaking phenomenon. The established theoretical model is based on fluid mechanics and incorporates the Chisholm model to analyze two-phase flow. From Bernoulli&#39;s equation, the velocity, quantity, undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be obtained or calculated. Moreover, to utilize the model established in this study, a siphon breaker analysis and design program was developed. The simulation program operates on the theoretical model basis and returns the result as a graph. The user can confirm the possibility of the siphon breaking by checking the shape of the graph. Furthermore, saving the entire simulation result is possible and it can be used as a resource for analyzing the real siphon breaking system.
In conclusion, the user can confirm the status of the siphon breaking and design the siphon breaker system using the program developed in this study.

The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

研究堆虹吸断路器试验与仿真研究

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape method or individual WS2 nanotubes by dispersing the suspension of WS2 nanotubes. The selected samples have been fabricated into devices by the use of the electron beam lithography and electrolyte is put on the devices. We have characterized the electronic properties of the devices under applying the gate voltage. In the small gate voltage region, ions in the electrolyte are accumulated on the surface of the samples which leads to the large electric potential drop and resultant electrostatic carrier doping at the interface. Ambipolar transfer curve has been observed in this electrostatic doping region. When the gate voltage is further increased, we met another drastic increase of source-drain current which implies that ions are intercalated into layers of WS2 and electrochemical carrier doping is realized. In such electrochemical doping region, superconductivity has been observed. The focused technique provides a powerful strategy for achieving the electric-filed-induced quantum phase transition.

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Here, we present a protocol to control the carrier number in solids by using the electrolyte.

用电解质浇注法对 WS2纳米器件电子态的电场控制

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape ...