Owing to the low-gravity conditions in space, space-borne laboratories enable experiments with extended free-fall times. Because Bose-Einstein condensates have an extremely low expansion energy, ...space-borne atom interferometers based on Bose-Einstein condensation have the potential to have much greater sensitivity to inertial forces than do similar ground-based interferometers. On 23 January 2017, as part of the sounding-rocket mission MAIUS-1, we created Bose-Einstein condensates in space and conducted 110 experiments central to matter-wave interferometry, including laser cooling and trapping of atoms in the presence of the large accelerations experienced during launch. Here we report on experiments conducted during the six minutes of in-space flight in which we studied the phase transition from a thermal ensemble to a Bose-Einstein condensate and the collective dynamics of the resulting condensate. Our results provide insights into conducting cold-atom experiments in space, such as precision interferometry, and pave the way to miniaturizing cold-atom and photon-based quantum information concepts for satellite-based implementation. In addition, space-borne Bose-Einstein condensation opens up the possibility of quantum gas experiments in low-gravity conditions
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Ultracold atom interferometry in space Lachmann, Maike D; Ahlers, Holger; Becker, Dennis ...
Nature communications,
02/2021, Letnik:
12, Številka:
1
Journal Article
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Bose-Einstein condensates (BECs) in free fall constitute a promising source for space-borne interferometry. Indeed, BECs enjoy a slowly expanding wave function, display a large spatial coherence and ...can be engineered and probed by optical techniques. Here we explore matter-wave fringes of multiple spinor components of a BEC released in free fall employing light-pulses to drive Bragg processes and induce phase imprinting on a sounding rocket. The prevailing microgravity played a crucial role in the observation of these interferences which not only reveal the spatial coherence of the condensates but also allow us to measure differential forces. Our work marks the beginning of matter-wave interferometry in space with future applications in fundamental physics, navigation and earth observation.
One important building block for future integrated nanophotonic devices is the scalable on-chip interfacing of single photon emitters and quantum memories with single optical modes. Here we present ...the deterministic integration of a single solid-state qubit, the nitrogen-vacancy (NV) center, with a photonic platform consisting exclusively of SiO2 grown thermally on a Si substrate. The platform stands out by its ultra-low fluorescence and the ability to produce various passive structures such as high-Q microresonators and mode-size converters. By numerical analysis an optimal structure for the efficient coupling of a dipole emitter to the guided mode could be determined. Experimentally, the integration of a preselected NV emitter was performed with an atomic force microscope and the on-chip excitation of the quantum emitter as well as the coupling of single photons to the guided mode of the integrated structure could be demonstrated. Our approach shows the potential of this platform as a robust nanoscale interface of on-chip photonic structures with solid-state qubits.
The authors report on design, fabrication, and electro‐optical characterization of single‐frequency diode lasers emitting around 696, 707, and 712 nm. This has been achieved by a variation of the ...periods of the 10th order surface Bragg gratings implemented on a single epitaxial wafer. Depending on the wavelength, the devices achieved an optical output power of up to 60 mW at a current of 150 mA and spectral linewidths of about 400 kHz (full width at half maximum (FWHM)) and 20 kHz (Lorentzian).
The aim of this study is to detect ventilation corridors in three epochs (1992, 2002 and 2011) by mapping rough urban areas. The roughness parameters calculations are based on a 3D building database ...obtained from satellite imagery (SPOT) for thee epochs and are conducted accordingly to morphometric methods. Several ventilation paths are clearly recognisable for all three decades and based on the proximity analysis and roughness parameters (by calculating roughness length (z
0
) and zero-plane displacement height (z
d
)), we established their extent and analysed the structural and developmental changes. We conducted that changes occurred more rapidly in the second period - almost 90% of the study area was gradually built up, what obstructs the air flow. In addition, winds are blocked in the western part of the city - where the best wind conditions occur. The results urge to re-evaluate the current shape of ventilation corridors and suggest some new areas that should be included in the air ventilation system to improve citizens' comfort and urban climate.
We determine Faraday rotations and measure the optical reflection and transmission from magneto-optical Cd1−xMnxTe crystals with various stoichiometric ratios. For wavelengths between 675 and ...1025 nm, we derive Verdet constants, optical loss coefficients, and the complex indices of reflection that are relevant measures to find suitable stoichiometric ratios of Cd1−xMnxTe for the realization of miniaturized optical isolators. By reflection and transmission measurements, we determine the stoichiometric ratios of several different Cd1−xMnxTe crystals and discuss the observed dependence of the optical properties on the stoichiometric ratio with respect to their use in optical isolators. Finally, we show the relevant figure of merit, i.e., the ratio of Verdet constants and optical loss coefficients for Cd1−xMnxTe crystals with Mn contents ranging from x = 0.14 to x = 0.50.
This paper reports the results of numerical and experimental investigations of the dynamics of an external-cavity diode laser device composed of a semiconductor laser and an external Bragg grating, ...which provides optical feedback. Due to the influence of the feedback, this system can operate in different dynamic regimes. The traveling-wave model is used for simulations and analysis of the nonlinear dynamics in the considered laser device. Based on this model, a detailed analysis of the optical modes is performed, and the stability of the stationary states is discussed. It is shown that the results obtained from the simulation and analysis of the device are in a good qualitative agreement with the experimental findings.
Cities, recognized as one of the roughest surfaces, significantly reduce wind velocity. This leads to a greater concentration of pollution and increased temperature in urban areas. A proper urban ...design may promote the air flow and mitigate these negative phenomena. This paper describes a novel approach to detect and analyze the potential urban ventilation corridors. The concept is based on the morphometric analyses, where roughness parameters (such as roughness length and displacement height), as well as porosity are investigated as opposed to previous studies. Commonly available light detection and ranging (LiDAR) data enable more detailed terrain study, as the topography and obstacle features (type, dimensions, and porosity) might be investigated. In comparison to the previous studies and long adapted practices, this approach takes advantage of all information incorporated in LiDAR data to deliver even more accurate results. The comparison of the detected corridors, with the officially designed corridors in our study area in Warsaw, suggests inaccuracies in their extent (only 40% of their areas might still be functioning) and calls for an evaluation. The results deliver areas that may be recognized as urban ventilation corridors and serve as air regeneration and ventilation system. They may also be used for developing new solutions for continuously evolving cities.
The influence of the front facet reflectivity on the spectral linewidth of high power DFB (distributed feedback) diode lasers emitting at 780 nm has been investigated theoretically and ...experimentally. Characterization of lasers at various front facet reflections showed substantial reduction of the linewidth. This behavior is in reasonable agreement with simulation results. A minimum linewidth of 8 kHz was achieved at an output power of 85 mW with the laser featuring a front facet reflectivity of 30%. The device with a front facet reflectivity of 5% reached the same linewidth value at an output power of 290 mW.
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