In system-level high-altitude electromagnetic pulse (HEMP) illumination tests, it is common to perform the test in two orthogonal polarizations of the incident electric field. With the judgment standard of the electromagnetic norm, this paper evaluated, improved, generalized, and verified this method. The evaluated result shows that the maximum error of the maximum coupling in this method is less than 3 dB. Meanwhile, this method is improved by serving the 1.2 period of the larger coupling of the 2 illuminations as the maximum coupling. The maximum error can be controlled within 1.5 dB. Moreover, this method is generalized to non-orthogonal conditions. Expressions of the deviations of this method are strictly derived. Based on this method, the application and some extended thinking are discussed. At last, a current coupling test is designed and carried out to verify the methods and conclusions. The methods introduced in this paper can be applied to any linear system in the illumination test under approximate transverse electromagnetic (TEM) waves.

Bias drift can always be a difficult problem in the application of electro-optical (EO) sensors based on intensity demodulation method, which may lead to the output jitter and distortion of the waveform. The bias drift problem can be avoided using a two-wavelength phase demodulation scheme, however the system noise restricts its use to low amplitude measurements. In this paper, the existing two-wavelength phase demodulation method is improved to overcome the limitation of low amplitude measurement for pulsed signals. The improved method can effectively avoid the bias drift problem compared with the intensity demodulation method and reduce the measurement limit by more than one order of magnitude compared with the phase demodulation method simultaneously. Based on the asymmetric two-wavelength EO modulation structure, we obtain the transfer function and its explicit demodulation formula without the bias term. Particularly, by adjusting the bias difference of the two lasers in the EO sensor to π/2, the modulated signal is simply proportional to the root mean square of the 2-channel outputs. To support and illustrate our method, a simulation, and a verification experiment are carried out and show that the demodulated signals have good consistency with each other.

A complete quantum cooling cycle may be a useful platform for studying quantum thermodynamics just as the quantum heat engine does. Entropy change is an important feature which can help us to investigate the thermodynamic properties of the single ion cooling process. Here, we analyze the entropy change of the ion and laser field in the single ion cooling cycle by generalizing the idea in Reference (Phys. Rev. Lett. 2015, 114, 043002) to a single ion system. Thermodynamic properties of the single ion cooling process are discussed and it is shown that the Second and Third Laws of Thermodynamics are still strictly held in the quantum cooling process. Our results suggest that quantum cooling cycles are also candidates for the investigation on quantum thermodynamics besides quantum heat engines.