Zero-point electromagnetic fields were first introduced to explain the origin of atomic spontaneous emission. Vacuum fluctuations associated with the zero-point energy in cavities are now utilized in ...quantum devices such as single-photon sources, quantum memories, switches and network nodes. Here we present three-dimensional (3D) imaging of vacuum fluctuations in a high-Q cavity based on the measurement of position-dependent emission of single atoms. Atomic position localization is achieved by using a nanoscale atomic beam aperture scannable in front of the cavity mode. The 3D structure of the cavity vacuum is reconstructed from the cavity output. The root mean squared amplitude of the vacuum field at the antinode is also measured to be 0.92+-0.07V/cm. The present work utilizing a single atom as a probe for sub-wavelength imaging demonstrates the utility of nanometre-scale technology in cavity quantum electrodynamics.
This paper describes a novel atom-cavity interaction induced by periodically poled atom-cavity coupling constant which leads to multiple narrow photoemission bands for an initially inverted two-level ...atom under the strong coupling condition. The emission bandpass narrowing has a close analogy with the folded Solc filter in the context of quasi-phase matching by periodic poling. We present a closed form solution of the emission probability at the end of interaction and deduce the multiple phase matching condition for this system which is programmable by the interaction time. The Bloch sphere analysis provides a clear understanding of the underlying atomic dynamics associated with the multiple resonances in the semiclassical limit. Furthermore, we show that this interaction can be applied to generation of the nonclassical field with sub-Poisson photon statistics.
We demonstrate lineshape measurement of an extreme-weak amplitude fluctuating
light source by using the photon-counting-based second-order correlation
spectroscopy combined with the heterodyne ...technique. The amplitude fluctuation
of a finite bandwidth introduces a low-lying spectral structure in the
lineshape and thus its effect can be isolated from that of the phase
fluctuation. Our technique provides extreme sensitivity suited for
single-atom-level applications.
We analyze theoretically the effect of technical fluctuations on laser
lineshape in terms of statistics of amplitude and phase noise and their
respective bandwidths. While the phase noise tends to ...broaden the linewidth as
the magnitude of the noise increases, the amplitude noise brings out an
additional structure with its spectral density reflecting the magnitude of the
noise. The effect of possible coupling between those two noises is also
discussed.
We demonstrate lineshape measurement of an extreme-weak amplitude fluctuating light source by using the photon-counting-based second-order correlation spectroscopy combined with the heterodyne ...technique. The amplitude fluctuation of a finite bandwidth introduces a low-lying spectral structure in the lineshape and thus its effect can be isolated from that of the phase fluctuation. Our technique provides extreme sensitivity suited for single-atom-level applications.
We analyze theoretically the effect of technical fluctuations on laser lineshape in terms of statistics of amplitude and phase noise and their respective bandwidths. While the phase noise tends to ...broaden the linewidth as the magnitude of the noise increases, the amplitude noise brings out an additional structure with its spectral density reflecting the magnitude of the noise. The effect of possible coupling between those two noises is also discussed.
This study presents the potential for improving energy performance by considering thermal performance degradation due to the aging of building envelopes. The U-value is a critical parameter for ...simulating a building's energy performance evaluation. However, because of the difficulty of in-situ measurements, many cases involve using standard or normative values for assessment. Nevertheless, considering the degradation of the external wall's insulation performance due to aging is crucial. We measured the thermal transmittance of external walls in 62 aged buildings constructed in various periods and quantitatively derived the degree of insulation performance degradation by comparing it with the legal standards at the time of construction. Moreover, to analyze the problems caused by neglecting the U-value deterioration in evaluating the energy-saving potential through retrofitting, a case study was conducted on 70 aged buildings where actual retrofit projects were implemented. We compared the cases by applying both legal thermal transmittance standards and corrected values based on actual measurements to the sites' pre-retrofit energy simulation models. The measurements showed that the aged buildings had an average insulation performance degradation of 49.69 % compared to the legal standards at the time of approval. Simply using the legal standard for the external wall's thermal transmittance underestimated the energy savings by 16.73 %. Furthermore, the study confirmed that correcting the U-value based on actual measurement data is essential for accurately evaluating the retrofit effect on aged buildings.
•Insulation degradation was quantified via in-situ measurements of 62 aged buildings.•Insulation degradation's impact was assessed with 70 real-world retrofit project data.•Using legal U-values underestimated retrofit energy savings by 16.73 % on average.•U-value correction based on measurements is crucial for accurate retrofit assessment.
Energy poverty, defined as difficulty meeting the minimum requirements for a thermal environment, is becoming a significant social issue. To provide efficient welfare services, information provision ...and monitoring are required. However, characteristics of energy poverty, such as inconsistent residential patterns, small living spaces, and limited electricity and telecommunication resources, lead to a lack of information. This research introduces the empirical results of the development of the system. Based on the feedback from welfare workers and experts supporting energy poverty, a monitoring system combining various sensors was prototyped. This system measures temperature, humidity, illuminance, air velocity, CO2, black bulb temperature, occupancy, and noise and generates indicators for occupancy and thermal environment monitoring. Applicability assessment was conducted across 55 energy poverty households in Korea during the duration of cooling and heating. Subjects were living in spaces averaging 6.3 sqm within buildings over 43 years old and renting on a monthly or weekly basis. Electricity and communication are partially supplied. Based on the actual measurement data and field surveys, the configuration of an energy poverty monitoring system was proposed. In particular, the applicability of the simple methodology for the determination of black bulb temperature, metabolic rate, and clothing insulation required for a thermal environment evaluation was assessed. The proposed system can be efficiently used for taking care of energy poverty where the installation of conventional monitoring systems is restricted.
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