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相关概念视频

Uncertainty in Measurement: Reading Instruments02:46

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Counting is the type of measurement that is free from uncertainty, provided the number of objects being counted does not change during the process. Such measurements result in exact numbers. By counting the eggs in a carton, for instance, one can determine exactly how many eggs are there in the carton. Similarly, the numbers of defined quantities are also exact. For example, 1 foot is exactly 12 inches, 1 inch is exactly 2.54 centimeters, and 1 gram is exactly 0.001 kilograms. Quantities...
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Uncertainty in Measurement: Accuracy and Precision03:37

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Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to evaluate both the precision and the accuracy of their results. Measurements are said to be precise if they yield very similar results when repeated in the same manner. A measurement is considered accurate if it yields a result that is very close to the true or the accepted value. Precise values agree with each other; accurate values agree with a true value. 
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The atomic mass of an element varies due to the relative ratio of its isotopes. A sample's relative proportion of oxygen isotopes influences its average atomic mass. For instance, if we were to measure the atomic mass of oxygen from a sample, the mass would be a weighted average of the isotopic masses of oxygen in that sample. Since a single sample is not likely to perfectly reflect the true atomic mass of oxygen for all the molecules of oxygen on Earth, the mass we obtain from this...
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Scientists always try their best to record measurements with the utmost accuracy and precision. However, sometimes errors do occur. These errors can be random or systematic. Random errors are observed due to the inconsistency or fluctuation in the measurement process, or variations in the quantity itself that is being measured. Such errors fluctuate from being greater than or less than the true value in repeated measurements. Consider a scientist measuring the length of an earthworm using a...
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System stability is a fundamental concept in signal processing, often assessed using convolution. For a system to be considered bounded-input bounded-output (BIBO) stable, any bounded input signal must produce a bounded output signal. A bounded input signal is one where the modulus does not exceed a certain constant at any point in time.
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Understanding the stability of equilibrium configurations is a fundamental part of mechanical engineering. In any system, there are three distinct types of equilibrium: stable, neutral, and unstable.
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Updated: Sep 12, 2025

Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
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高稳定性单离子时钟,系统不确定性为5.5×10^{-19}

Mason C Marshall1, Daniel A Rodriguez Castillo1,2, Willa J Arthur-Dworschack1,2

  • 1National Institute of Standards and Technology, Time and Frequency Division, Boulder, Colorado, USA.

Physical review letters
|August 4, 2025
PubMed
概括
此摘要是机器生成的。

我们开发了一个单个离子 (Al+) 原子钟,实现了前所未有的精度. 这个量子逻辑时钟显示了5.5x10^-19的不确定性,这是精确计时的重大进步.

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科学领域:

  • 原子物理 原子物理
  • 量子计算是一种量子计算.
  • 计量学 计量学 计量学

背景情况:

  • 原子钟对于科学研究和技术至关重要.
  • 以前的离子 (Al+) 时钟面临着稳定性和系统性不确定性的限制.
  • 量子逻辑光谱学为增强原子钟性能提供了一条途径.

研究的目的:

  • 开发一个单离子光学原子钟,提高分数频率的不确定性和稳定性.
  • 为了利用量子逻辑光谱来进行高精度测量 ^{27}Al^{+}时钟过渡.
  • 通过改进实验设计和测量来减少系统性不确定性.

主要方法:

  • 在单个^{27}Al^{+}离子上利用了量子逻辑光谱学.
  • 采用共感冷却和读取,使用一个cotrapped ^{25}Mg^{+}离子.
  • 实现了激光稳定转移从一个遥远的冷腔通过3.6公里的光纤连接.
  • 改进了离子陷设计以最大限度地减少微运动,并采用了新的真空系统以减少碰撞转移.
  • 进行了对磁场方向敏感的测量,以消除与方向相关的系统不确定性.

主要成果:

  • 获得了5.5×10^{-19} 的分数频率不确定性.
  • 证明了3.5×10^{-16}/sqrt[τ/s]的分数频率稳定性.
  • 与之前的 ^{27}Al^{+} 时钟相比,由于1秒的拉比探针持续时间,时钟不稳定性减少了三倍.
  • 通过减少微运动和碰撞转移,降低了系统不确定性.
  • 消除了RF离子陷和磁场方向的系统不确定性.

结论:

  • 开发的单离子光学原子钟代表了精确计时的重大进步.
  • 采用的技术,包括激光稳定转移和改进的实验设计,为未来超精确的原子钟铺平了道路.
  • 这项工作有助于对原子系统的基本理解及其在计量学中的应用.