The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Eric G. Brown - One of the best experts on this subject based on the ideXlab platform.
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What does it mean for half of an Empty Cavity to be full
Physical Review D, 2015Co-Authors: Eric G. BrownAbstract:It is well known that the vacuum state of a quantum field is spatially entangled. This is true both in free and confined spaces, for example in an optical Cavity. The obvious consequence of this, however, is surprising and intuitively challenging; namely, that in a mathematical sense half of an Empty Cavity is not Empty. Formally this is clear, but what does this physically mean in terms of, say, measurements that can actually be made? In this paper we utilize the tools of Gaussian quantum mechanics to easily characterize the reduced state of a subregion in a Cavity and expose the spatial profile of its entanglement with the opposite region. We then go on to discuss a thought experiment in which a mirror is introduced between the regions. In so doing we expose a simple and physically concrete answer to the above question: the vacuum excitations resulting from entanglement are mathematically equivalent to the real excitations generated by suddenly introducing a mirror. Performing such an experiment in the laboratory may be an excellent method of verifying vacuum entanglement, and we conclude by discussing different possibilities of achieving this aim.
Jonas Larson - One of the best experts on this subject based on the ideXlab platform.
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Monitoring the resonantly driven Jaynes-Cummings oscillator by an external two-level emitter : A cascaded open-systems approach
Physical Review A, 2020Co-Authors: Themistoklis K. Mavrogordatos, Jonas LarsonAbstract:We address the consequences of back action in the unidirectional coupling of two cascaded open quantum subsystems connected to the same reservoir at different spatial locations. In the spirit of H. J. Carmichael [Phys. Rev. Lett. 70, 2273 (1993)], the second subsystem is a two-level atom, while the first transforms from a driven Empty Cavity to a perturbative QED configuration and ultimately to a driven Jaynes-Cummings (JC) oscillator through a varying light-matter coupling strength. For our purpose, we appeal at first to the properties of resonance fluorescence in the statistical description of radiation emitted along two channels---those of forward and sideways scattering---comprising the monitored output. In the simplest case of an Empty Cavity coupled to an external atom, we derive analytical results for the nonclassical fluctuations in the fields occupying the two channels, pursuing a mapping to the bad-Cavity limit of the JC model to serve as a guide for the description of the more involved dynamics. Finally, we exemplify a conditional evolution for the composite system of a critical JC oscillator on resonance coupled to an external monitored two-level target, showing that coherent atomic oscillations of the target probe the onset of a second-order dissipative quantum phase transition in the source.
Kunchi Peng - One of the best experts on this subject based on the ideXlab platform.
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Quantum self-homodyne tomography with an Empty Cavity
Journal of the Optical Society of America B, 2000Co-Authors: Jing Zhang, Tiancai Zhang, Changde Xie, Kuanshou Zhang, Kunchi PengAbstract:We develop a scheme to reconstruct the optical quantum state of a single-mode bright light field by using the dispersion characteristics of the Empty Cavity. The input field has a strong coherent component at frequency ω0, which serves as a local oscillator (LO) to measure its two-sideband mode at ω0±Ω. We control the relative phase of the 0–2π range between the LO and the two-sideband mode by scanning the Cavity length, so the optical quantum state is tomographically reconstructed. In the proposed scheme the influence of the space-mode mismatch between the LO and measured mode on the quantum efficiency is eliminated, and this scheme can conveniently be used in some quantum optical systems in which LO field cannot be available.
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Single-Mode Self-Homodyne Tomography with Empty Cavity
Frontiers of Laser Physics and Quantum Optics, 2000Co-Authors: Jing Zhang, Junxiang Zhang, Tiancai Zhang, Changde Xie, Kunchi PengAbstract:A self-homodyne detection scheme with Empty Cavity is proposed to perform quantum tomography of single-mode which have a strong mean field. The local oscillator used in conventional homodying is not needed in the proposed scheme and the overall quantum efficiency can be improved.
John Colton - One of the best experts on this subject based on the ideXlab platform.
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Resonance of Complex Cylindrically Symmetric Cavities Using an Eigenfunction Expansion in Empty Cavity Modes
IEEE Transactions on Microwave Theory and Techniques, 2016Co-Authors: Kyle G. Miller, Michael Meehan, Ross L. Spencer, John ColtonAbstract:This paper presents a new method for calculating the Cavity modes of cylindrically symmetric cavities and applies the method to stacked dielectric resonators (DRs) inside a conducting cylindrical shell. The modes of an arbitrary Cavity are expressed using an eigenfunction expansion, the basis functions being the fields of an Empty Cavity. The wave equation for the electric displacement field, $D$ , can be manipulated to eliminate derivatives of the discontinuous dielectric constant and provide an eigenvalue equation for the resonant frequencies of the Cavity. The eigenvectors specify coefficients of the Empty Cavity modes that sum to compose the electric and magnetic fields. A test against theory is presented for an infinitely long dielectric cylinder inside an infinitely long cylindrical Cavity, and the accuracy is better than 0.4% for nearly all modes. The calculated resonant frequencies of the quasi-TE011 (TE $_{{\mathrm {01\delta }}}$ ) mode are also compared with the experimentally measured frequencies of resonant cavities containing DRs for ten different configurations; the results display an accuracy of better than 1.0% in all but one case. A link to a MATLAB implementation of the technique is provided.
Lidong Chen - One of the best experts on this subject based on the ideXlab platform.
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Numerical and experimental analysis for exhaust heat exchangers in automobile thermoelectric generators
Case Studies in Thermal Engineering, 2014Co-Authors: Hongliang Lu, Ting Wu, Lidong ChenAbstract:Abstract Ideal heat exchangers recover as much heat as possible from an engine exhaust at the cost of an acceptable pressure drop. They provide primary heat for a thermoelectric generator (TEG), and their capacity and efficiency is dependent on the material, shape, and type of the heat exchanger. Six different exhaust heat exchangers were designed within the same shell, and their computational fluid dynamics (CFD) models were developed to compare heat transfer and pressure drop in typical driving cycles for a vehicle with a 1.2 L gasoline engine. The result showed that the serial plate structure enhanced heat transfer by 7 baffles and transferred the maximum heat of 1737 W. It also produced a maximum pressure drop of 9.7 kPa in a suburban driving cycle. The numerical results for the pipe structure and an Empty Cavity were verified by experiments. Under the maximum power output condition, only the inclined plate and Empty Cavity structure undergoes a pressure drop less than 80 kPa, and the largest pressure drop exceeds 190 kPa. In this case, a mechanism with a differential pressure switch is essential to bypass part of the exhaust.
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experiment on thermal uniformity and pressure drop of exhaust heat exchanger for automotive thermoelectric generator
Energy, 2013Co-Authors: Hongliang Lu, Ting Wu, Kangcong Xu, Yingjie Huang, Lidong ChenAbstract:The power generation of exhaust TEG (thermoelectric generator) depends on heat energy and thermoelectric conversion efficiency. High efficiency heat exchanger is necessary to increase the amount of heat energy extracted from exhaust gas. On one hand, heat transfer is coupled with pressure drop for typical heat exchanger; on the other hand, the muffler unavoidably leads exhaust to large pressure drop for noise reduction. The present work tried to conceptually combine exhaust heat exchanger with muffler in the form of 1-inlet 2-outlet, 2-inlet 2-outlet and the baseline Empty Cavity. A test bench was developed to compare thermal uniformity and pressure drop characteristics over multiple vehicle operating conditions. 1-Inlet 2-outlet increased hydraulic disturbance and enhanced heat transfer, resulting in the more uniform flow distribution and higher surface temperature than the other. However, the averaged surface temperature was less than 100 °C, significantly limiting thermoelectric conversion efficiency. The pressure drops of 1-inlet 2-outlet, 2-inlet 2-outlet were 165%, 318% more than that of Empty Cavity when inlet temperature was 100 °C and mass flow rate was 131 kg/h, and were 319%, 523% more than that of Empty Cavity when inlet temperature 400 °C and mass flow rate 156 kg/h.