- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Brightening of a supersonic beam of neutral atoms
摘要： Well-collimated, high-intensity beams of neutral atoms have many applications ranging from atom microscopy to atom interferometry to ultracold atomic physics. We experimentally demonstrate a method for brightening a supersonic atomic beam and observe an increase in the phase space density by a factor of at least 20. Our scheme relies upon a permanent magnetic hexapole lens to focus a divergent beam of neutral atoms emitted from a supersonic nozzle and transverse laser cooling as the beam converges downstream from the lens so as to create a dense, narrow, Doppler-collimated atomic beam. In principle, this method can be repeated multiple times in series for further beam brightening.
关键词： atomic focusing,beam brightening,supersonic beam,laser cooling,magnetic hexapole
更新于2025-09-09 09:28:46
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Compact Cold-Atom Clock for Onboard Timebase: Tests in Reduced Gravity
摘要： We present a compact atomic clock using cold rubidium atoms based on an isotropic light cooling, a Ramsey microwave interrogation, and an absorption detection. Its technology readiness level is suitable for industrial transfer. We use a fiber optical bench, based on a frequency-doubled telecom laser. The isotropic light cooling technique allows us to cool down the atoms in 100 ms and works with a cycle time of around 200 ms. We carry out measurements in simulated microgravity and obtain narrow fringes, up to 1.25 Hz.
关键词： microgravity,compact atomic clock,absorption detection,cold rubidium atoms,isotropic light cooling,Ramsey microwave interrogation
更新于2025-09-09 09:28:46
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Modelo clássico para resfriamento at?mico: Uma forma pedagógica de entender o problema
摘要： In this work we develop a classical model to describe the laser cooling process due to the interaction between an atom and a con(cid:12)guration of laser beams. We derive an expression for the radiation force exerted on the atom, detailing the origin of each term involved. Lastly, we built a parallel between the classical model and the peculiarities of the quantum nature of the interaction radiation-matter.
关键词： radiation,laser,classical physics,atoms,cooling
更新于2025-09-04 15:30:14
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in a hybrid trap
摘要： We report on the production of a 41K-87Rb dual-species Bose-Einstein condensate in a hybrid trap, consisting of a magnetic quadrupole and an optical dipole potential. After loading both atomic species in the trap, we cool down 87Rb first by magnetic and then by optical evaporation, while 41K is sympathetically cooled by elastic collisions with 87Rb. We eventually produce two-component condensates with more than 105 atoms and tunable species population imbalance. We observe the immiscibility of the quantum mixture by measuring the density profile of each species after releasing them from the trap.
关键词： Bose-Einstein condensate,immiscibility,hybrid trap,dual-species,sympathetic cooling
更新于2025-09-04 15:30:14
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Precise Measurement of Transition Frequencies of Optically Trapped <sup>40</sup> Ca <sup>19</sup> F Molecules
摘要： The laser cooling and trapping of molecules have recently been achieved. In this paper, the possibility of precisely measuring the vibrational transition frequencies of optically trapped 40Ca19F molecules is discussed. The quadratic Stark shift induced by the trap laser is eliminated using the trap laser frequencies where the Stark energy shifts at upper and lower states are equal (magic frequencies). At one value of the magic frequency, molecules are trapped at the positions where the power density is minimum, therefore, the measurement is not sensitive to the detuning of the trap laser frequency from the magic frequency. Measurement with an uncertainty of 10?17 appears to be possible using the ev; N; J; F; MT ? e0; 0; 1=2; 1; (cid:2)1T ! e1; 0; 1=2; 1; (cid:2)1T transition frequency.
关键词： laser cooling,Stark shift,magic frequencies,molecules,vibrational transition frequencies,trapping
更新于2025-09-04 15:30:14
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Improving the cooling of a mechanical oscillator in a dissipative optomechanical system with an optical parametric amplifier
摘要： The ground-state cooling of a macroscopic mechanical oscillator is a crucial prerequisite for implementing the quantum manipulation of the mechanical oscillator. Here we show that a degenerate optical parametric amplifier (OPA) can significantly improve the cooling of the mechanical membrane in the purely dissipative coupling system in the unresolved sideband regime. In the presence of the OPA with a parametric phase π/2, the mechanical membrane can be cooled from room temperature 293 K to 10 mK, a factor of 112 lower than that in the absence of the OPA. If the mechanical oscillator is precooled to 0.1 K, the mechanical membrane can be cooled into the microkelvin regime.
关键词： optical parametric amplifier,dissipative optomechanical system,ground-state cooling,mechanical oscillator
更新于2025-09-04 15:30:14
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Novel Design for Thermal Management of PV Cells in Harsh Environmental Conditions
摘要： The abundance of solar energy is a blessing in the Arabian Peninsula, where more than 2000 kWh/m2 density has been recorded annually. This has resulted in sincere consideration of PV harvesting in the energy matrix and smart grid. However, artefacts such as degradation of PV efficiency due to the high temperature effect have to be addressed. This paper presents a novel design of a PV cooling system using water to mitigate the effect of high temperature. Several experiments have been conducted, and the results have been analyzed. It has been found that the collected water from the panel after 40 min of cooling gained a temperature of 10 ?C approximately, during December 2016. Eventually, the efficiency was improved by 10.35% (without using MPPT) using water at ambient temperature (24 ?C) compared to the non-cooled panel. Moreover, the temperature of the panel during solar peak hours dropped from 64.3 ?C to 32 ?C and from 59 ?C to 27 ?C in 3 min for the back and front surface, respectively. These results, which are the ?rst of their kind in Qatar, constitute good incentives and pave the way for further investigation to enhance PV ef?ciency in harsh environments. This would be of paramount signi?cance, especially for scaling up PV deployment, as is planned in Qatar and GCC countries in their 2030 vision.
关键词： overheating,ef?ciency,photovoltaic,water cooling,heat transfer,renewable energy
更新于2025-09-04 15:30:14