Electron Magnetic Moment, Fine Structure Constant, Mass Ratios, Laser Spectroscopy and QED

电子磁矩、精细结构常数、质量比、激光光谱和 QED

• 批准号: 0555508
• 负责人: Gerald Gabrielse
• 金额: $ 125万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0555508&HistoricalAwards=false
• 关键词: Electron; Magnetic; Moment; Fine; Structure

This project represents a continuation of a long series of experiments that pose ever-increasingly more stringent tests of fundamental quantities and symmetries, including:1. the electron magnetic moment (often called its g value)2. the fine structure constant alpha3. most stringent test of CPT (charge-parity-time) invariance with leptons4. the ratio of the masses of the proton and electron5. the proton and antiproton magnetic momentsTechnological spinoffs of this research have been incorporated into ion cyclotron resonance spectroscopy and magnetic resonance imaging, and the improvement of promising new detectors continues, demonstrating broader applicability. A better value of alpha is crucial to determining a number of the set of fundamental constants that are needed by a technological society. Quantum electrodynamics (QED) incorporates alpha into its description of the interaction of matter and light. It is the prototype quantum field theory, serving as the model which theoretical efforts to describe strong interactions and gravity seek to emulate. An outstanding achievement of QED is the predicted relationship between the electron magnetic moment g and alpha, which allows alpha to be determined by measuring g, Given the success of calculating the parameters describing this relationship, QED theory now contributes 43 times less uncertainty to g than do previous measurements. A sufficiently improved measurement of g will thus determine alpha 43 time more accurately. An independent measurement of alpha, along with the measurement of g, will test QED to an unprecedented level of accuracy the most precise comparison of any theory and experiment. The experimental precision, with the theoretical accuracy expected in calculations underway, should allow distinguishing between inconsistent values of alpha measured from the quantum Hall effect, the ac Josephson effect, and from a neutron measurement. An iodine clock and optical comb developed for this work, technologies of much broader applicability for communications, will make possible absolute frequency measurements and more accurate measurements of frequency intervals.

这个项目代表了一系列实验的延续，这些实验对基本量和对称性提出了越来越严格的测试，包括：1。电子磁矩（通常称为其g值）2。精细结构常数α 3。最严格的CPT（电荷宇称时间）与轻子不变性测试4。质子和电子的质量比。质子和反质子磁矩这项研究的技术副产品已被纳入离子回旋共振光谱学和磁共振成像，并继续改进有前途的新探测器，证明更广泛的适用性。一个更好的α值对于确定技术社会所需的一组基本常数至关重要。量子电动力学（QED）将α纳入其对物质与光相互作用的描述中。它是量子场论的原型，作为描述强相互作用和引力的理论努力试图模仿的模型。QED的一个突出成就是预测了电子磁矩g和α之间的关系，这使得α可以通过测量g来确定，考虑到计算描述这种关系的参数的成功，QED理论现在对g的不确定性比以前的测量少43倍。因此，g的充分改进的测量将更准确地确定α 43时间。对α的独立测量，沿着对g的测量，将把QED测试到前所未有的精确度，这是任何理论和实验中最精确的比较。 实验的精确度，加上正在进行的计算中预期的理论精确度，应该可以区分从量子霍尔效应、交流约瑟夫森效应和中子测量中测得的不一致的α值。 为这项工作开发的碘钟和光梳，对通信具有更广泛适用性的技术，将使绝对频率测量和更精确的频率间隔测量成为可能。