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161.
L. Stodolsky 《Physics Reports》1999,320(1-6):51-58
We discuss fluctuations in the measurement process and how these fluctuations are related to the dissipational parameter characterizing quantum damping or decoherence. On the example of the measuring current of the variable-barrier or QPC problem we discuss the extra noise or fluctuation connected with the different possible outcomes of a measurement. This noise has an enhanced short time component which could be interpreted as due to “telegraph noise” or “wavefunction collapses”. Furthermore, the parameter giving the strength of this component is related to the parameter giving the rate of damping or decoherence. 相似文献
162.
辐射是各种燃烧过程中热传递的主要方式。在不同的火焰中,辐射光谱分布十分复杂。在这项工作中,利用光谱仪测量了可见光(200~900 nm),近红外(900~1 700 nm)和中红外(2 500~5 000 nm)波段火焰的光谱强度,分析了空气和富氧气氛下扩散火焰的光谱特征。并基于光谱分析,定量得到了火焰中碳烟以及气体发射的辐射力,计算了火焰的温度分布。结果表明,空气燃烧中的火焰温度低于富氧燃烧中的火焰温度。在空气气氛下,火焰中的碳烟和气体均对中的热辐射起着重要作用。而在富氧气氛下,气体对于火焰热辐射更为重要。在可见光和近红外波段,由于在空气气氛下火焰中碳烟的大量形成,光谱曲线显示出了良好连续性。而富氧气氛下火焰的辐射光谱降低。在中红外波段,空气气氛下火焰的气体辐射明显弱于富氧气氛下火焰的气体辐射。 相似文献
163.
Timothy J. Hollowood 《Contemporary Physics》2016,57(3):289-308
In our quantum mechanics courses, measurement is usually taught in passing, as an ad-hoc procedure involving the ugly collapse of the wave function. No wonder we search for more satisfying alternatives to the Copenhagen interpretation. But this overlooks the fact that the approach fits very well with modern measurement theory with its notions of the conditioned state and quantum trajectory. In addition, what we know of as the Copenhagen interpretation is a later 1950s development and some of the earlier pioneers like Bohr did not talk of wave function collapse. In fact, if one takes these earlier ideas and mixes them with later insights of decoherence, a much more satisfying version of Copenhagen quantum mechanics emerges, one for which the collapse of the wave function is seen to be a harmless book keeping device. Along the way, we explain why chaotic systems lead to wave functions that spread out quickly on macroscopic scales implying that Schrödinger cat states are the norm rather than curiosities generated in physicists’ laboratories. We then describe how the conditioned state of a quantum system depends crucially on how the system is monitored illustrating this with the example of a decaying atom monitored with a time of arrival photon detector, leading to Bohr’s quantum jumps. On the other hand, other kinds of detection lead to much smoother behaviour, providing yet another example of complementarity. Finally we explain how classical behaviour emerges, including classical mechanics but also thermodynamics. 相似文献
164.
原子发射双谱线法测火焰温度的实验研究 总被引:1,自引:0,他引:1
通过光谱仪测量火焰中K(766.5,769.9 nm)原子发射谱线的相对强度比来获得火焰温度。介绍了测量原理、测量方法、实验系统。在黑体炉炉膛达到热力学平衡状态下,进行原子发射双谱线法和热电偶测温的对比实验,结果两种方法所测温度相关性较好,实验证明了该方法的可行性。用该方法测量煤粉和木材的火焰温度,结果和实际相符合。 相似文献
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166.
为了实现对球面镜真空紫外光谱反射率的直接测量,构建了一套真空紫外光谱反射率测试系统。该系统以氟化镁窗口氘灯与Seya-Namioka凹面光栅单色仪产生单色光源,反射式调制器与参考探测器做光学补偿,内径80mm的荧光积分球与精密转台作为接收系统。光学补偿消除单色光源不稳定性,荧光积分球消除了两次测量光斑不同对探测器响应的影响,且减少了系统的能量损失。利用该系统测量了115~180nm球面镜的反射率,测试结果表明测量重复性优于±0.3%;按国际通用不确定度评估规范,对系统进行不确定度分析,相关不确定度小于1.3%。实现了球面镜反射率的高精度测量。 相似文献
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169.
A quantization method based on replacement of c-number by c-number parameterized by an unbiased hidden random variable is developed. In contrast to canonical quantization, the replacement has a straightforward physical interpretation as a statistical modification of classical dynamics of an ensemble of trajectories, and implies a unique operator ordering. We then apply the method to develop quantum measurement without wave function collapse and external observer a la pilot-wave theory. 相似文献
170.
A computer simulation system of three-dimensional sensing with structured illumination is presented. It includes the generation of deformed fringe patterns from 3-D shapes and the reconstruction of 3-D shapes, conversely. Some experimental results of the deformed fringe pattern and the reconstructed object shapes are presented. We have also discussed the effect of some major system parameters on the measurement results and considered how to correct these parameters according to the measurement result of the standard plane. Using this simulation system, the major system parameters: environmental conditions, measurement accuracy and algorithm evaluation of the 3-D shape measurement system based on PMP, FTP, SPM, etc., can be researched. © 1997 Elsevier Science Ltd. All rights reserved. 相似文献