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Author(s):  
Yusuke Hisai ◽  
Yoshiki Nishida ◽  
Hiroshi Miyazawa ◽  
Takumi Kobayashi ◽  
Feng-Lei HONG ◽  
...  

Abstract We demonstrate a second harmonic generation (SHG) of 116 mW at 461 nm in a periodically poled lithium niobate waveguide when the power of the 922-nm fundamental light is coupled into the waveguide was 350 mW. The waveguide is 12.5 μm wide, 12.0 μm thick, 22 mm long, and has a 1-mm-long slab window at the output facet of the waveguide. The temperature acceptance bandwidth of the phase-matching curve of the SHG is approximately 0.5 °C. The SHG system demonstrates good beam quality and is reliable for cold atom experiments, including research on optical lattice clocks.


Author(s):  
Christian Siemes ◽  
Stephen Maddox ◽  
Olivier Carraz ◽  
Trevor Cross ◽  
Steven George ◽  
...  

AbstractCold Atom technology has undergone rapid development in recent years and has been demonstrated in space in the form of cold atom scientific experiments and technology demonstrators, but has so far not been used as the fundamental sensor technology in a science mission. The European Space Agency therefore funded a 7-month project to define the CASPA-ADM mission concept, which serves to demonstrate cold-atom interferometer (CAI) accelerometer technology in space. To make the mission concept useful beyond the technology demonstration, it aims at providing observations of thermosphere mass density in the altitude region of 300–400 km, which is presently not well covered with observations by other missions. The goal for the accuracy of the thermosphere density observations is 1% of the signal, which will enable the study of gas–surface interactions as well as the observation of atmospheric waves. To reach this accuracy, the CAI accelerometer is complemented with a neutral mass spectrometer, ram wind sensor, and a star sensor. The neutral mass spectrometer data is considered valuable on its own since the last measurements of atmospheric composition and temperature in the targeted altitude range date back to 1980s. A multi-frequency GNSS receiver provides not only precise positions, but also thermosphere density observations with a lower resolution along the orbit, which can be used to validate the CAI accelerometer measurements. In this paper, we provide an overview of the mission concept and its objectives, the orbit selection, and derive first requirements for the scientific payload.


2022 ◽  
Vol 71 (2) ◽  
pp. 026701-026701
Author(s):  
Cheng Bing ◽  
◽  
Chen Pei-Jun ◽  
Zhou Yin ◽  
Wang Kai-Nan ◽  
...  

2021 ◽  
Vol 127 (26) ◽  
Author(s):  
Zhong-Hua Qian ◽  
Jin-Ming Cui ◽  
Xi-Wang Luo ◽  
Yong-Xiang Zheng ◽  
Yun-Feng Huang ◽  
...  
Keyword(s):  

Author(s):  
Leonardo Badurina ◽  
Oliver Buchmueller ◽  
John Ellis ◽  
Marek Lewicki ◽  
Christopher McCabe ◽  
...  

We survey the prospective sensitivities of terrestrial and space-borne atom interferometers to gravitational waves generated by cosmological and astrophysical sources, and to ultralight dark matter. We discuss the backgrounds from gravitational gradient noise in terrestrial detectors, and also binary pulsar and asteroid backgrounds in space-borne detectors. We compare the sensitivities of LIGO and LISA with those of the 100 m and 1 km stages of the AION terrestrial AI project, as well as two options for the proposed AEDGE AI space mission with cold atom clouds either inside or outside the spacecraft, considering as possible sources the mergers of black holes and neutron stars, supernovae, phase transitions in the early Universe, cosmic strings and quantum fluctuations in the early Universe that could have generated primordial black holes. We also review the capabilities of AION and AEDGE for detecting coherent waves of ultralight scalar dark matter. AION-REPORT/2021-04 KCL-PH-TH/2021-61, CERN-TH-2021-116 This article is part of the theme issue ‘Quantum technologies in particle physics’.


2021 ◽  
Author(s):  
◽  
Markus Kotulla

<p>Recent discoveries have spurred the theoretical prediction and experimental realization of novel materials that have topological properties arising from band inversion. Such topological insulators have conductive surface or edge states but are insulating in the bulk. How the signatures of topological behavior evolve when the system size is reduced is noteworthy from both a fundamental and an application-oriented point of view, as such understanding may form the basis for tailoring systems to be in specific topological phases. This thesis investigates the softly confined topological insulator family of Bi₂Se₃ and its properties when subjected to an in-plane magnetic field. The model system provides a useful platform for systematic study of the transition between the normal and the topological phases, including the development of band inversion and the formation of massless-Dirac-fermion surface states. The effects of bare size quantization, two-dimensional-subband mixing, and electron-hole asymmetry are disentangled and their corresponding physical consequences elucidated.  When a magnetic field is present, it is found that the Dirac cone which is formed in surface states, splits into two cones separated in momentum space and that these cones exhibit properties of Weyl fermions. The effective Zeeman splitting is much larger for the surface states than for the bulk states. Furthermore, the g-factor of the surface states depends on the size of the material. The mathematical model presented here may be realizable experimentally in the frame of optical lattices in ultra cold atom gases.</p>


2021 ◽  
Author(s):  
◽  
Markus Kotulla

<p>Recent discoveries have spurred the theoretical prediction and experimental realization of novel materials that have topological properties arising from band inversion. Such topological insulators have conductive surface or edge states but are insulating in the bulk. How the signatures of topological behavior evolve when the system size is reduced is noteworthy from both a fundamental and an application-oriented point of view, as such understanding may form the basis for tailoring systems to be in specific topological phases. This thesis investigates the softly confined topological insulator family of Bi₂Se₃ and its properties when subjected to an in-plane magnetic field. The model system provides a useful platform for systematic study of the transition between the normal and the topological phases, including the development of band inversion and the formation of massless-Dirac-fermion surface states. The effects of bare size quantization, two-dimensional-subband mixing, and electron-hole asymmetry are disentangled and their corresponding physical consequences elucidated.  When a magnetic field is present, it is found that the Dirac cone which is formed in surface states, splits into two cones separated in momentum space and that these cones exhibit properties of Weyl fermions. The effective Zeeman splitting is much larger for the surface states than for the bulk states. Furthermore, the g-factor of the surface states depends on the size of the material. The mathematical model presented here may be realizable experimentally in the frame of optical lattices in ultra cold atom gases.</p>


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Rafael E. Barfknecht ◽  
Angela Foerster ◽  
Nikolaj T. Zinner ◽  
Artem G. Volosniev

AbstractTheoretical and experimental studies of the interaction between spins and temperature are vital for the development of spin caloritronics, as they dictate the design of future devices. In this work, we propose a two-terminal cold-atom simulator to study that interaction. The proposed quantum simulator consists of strongly interacting atoms that occupy two temperature reservoirs connected by a one-dimensional link. First, we argue that the dynamics in the link can be described using an inhomogeneous Heisenberg spin chain whose couplings are defined by the local temperature. Second, we show the existence of a spin current in a system with a temperature difference by studying the dynamics that follows the spin-flip of an atom in the link. A temperature gradient accelerates the impurity in one direction more than in the other, leading to an overall spin current similar to the spin Seebeck effect.


2021 ◽  
Author(s):  
Chandan Setty ◽  
Laura Fanfarillo ◽  
Peter Hirschfeld

Abstract In weakly coupled BCS superconductors, only electrons within a tiny energy window around the Fermi energy, EF, form Cooper pairs. This may not be the case in strong coupling superconductors such as cuprates, FeSe, SrTiO3 or cold atom condensates where the pairing scale, EB, becomes comparable or even larger than EF. In cuprates, for example, a plausible candidate for the pseudogap state at low doping is a fluctuating pair density wave, but no microscopic model has yet been found which supports such a state. In this work, we write an analytically solvable model to examine pairing phases in the strongly coupled regime and in the presence of anisotropic interactions. Already for moderate coupling we find an unusual finite temperature phase, below an instability temperature Ti, where local pair correlations have non-zero center-of-mass momentum but lack long-range order. At low temperature, this fluctuating pair density wave can condense either to a uniform d-wave super- conductor or the widely postulated pair-density wave phase depending on the interaction strength. Our minimal model offers a unified microscopic framework to understand the emergence of both fluctuating and long range pair density waves in realistic systems.


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