Journal of Low Temperature Physics最新文献

{"title":"Investigation of the Flow Field in the Pulse Tube Refrigerator with the Multi-Bypass Structure Through the Finite Element Method","authors":"ZeKun Wang,&nbsp;ChuShu Fang,&nbsp;Yuan Zhou,&nbsp;Laifeng Li","doi":"10.1007/s10909-023-02992-0","DOIUrl":"10.1007/s10909-023-02992-0","url":null,"abstract":"<div><p>The multi-bypass structure established a radial gas channel between the regenerator and the pulse tube in the pulse tube refrigeration. Numerical results of the flow field were obtained in two dimensions by the finite element method. Afterward, the position and thermal state of selected gas parcels were tracked with the tracking algorithms. The multi-bypass structure generates vortices at the pulse tube, and the existence of these vortices inhibits the capacity of the gas parcels to take heat away from the cold end. Placing porous material near the multi-bypass structure, it could effectively reduce the vortices in the pulse tube.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"138 - 153"},"PeriodicalIF":2.0,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4811287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Heat Capacity of (^3)He-B in Silica Aerogel","authors":"J. A. Sauls","doi":"10.1007/s10909-023-02996-w","DOIUrl":"10.1007/s10909-023-02996-w","url":null,"abstract":"<div><p>The thermodynamic potential for superfluid <span>(^3)</span>He-B embedded in a homogeneously distributed random potential is calculated from a quasiclassical reduction of the Luttinger–Ward functional to leading order in <span>({mathbf s} =k_{text {B}}T_c/E_f)</span>. The resulting functional provides an extension of the Ginzburg–Landau free energy functional to all temperatures <span>(0&lt;Tle T_c)</span>. Theoretical predictions based on this functional for the heat capacity of superfluid <span>(^3)</span>He-B embedded in homogeneous, isotropic silica aerogel are in good agreement with experimental reports for superfluid <span>(^3)</span>He-B infused into 98.2% porous silica aerogel over the pressure range <span>(p=11-29,text{ bar })</span>. The analysis supports a conclusion that superfluid <span>(^3)</span>He-B infused into high-porosity silica aerogels is a gapless superfluid at all pressures.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"42 - 50"},"PeriodicalIF":2.0,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4743316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Difference Between Type I and Type II Superconductors","authors":"Ulrich Köbler","doi":"10.1007/s10909-023-02991-1","DOIUrl":"10.1007/s10909-023-02991-1","url":null,"abstract":"<div><p>It is shown that for the metals that get superconducting, the heat capacity above the transition temperature, T_SC, is given by a sequence of power function of absolute temperature and not, as for the metals that do not get superconducting (Au, Ag, Cu…), by a superposition of a linear and a cubic term of absolute temperature. The two heat capacities have to be attributed to the relevant bosons in the critical range at <i>T</i> = 0. For the metals that get superconducting, the two boson fields interact and their heat capacities do no longer superimpose. Since the interaction details change with temperature, a sequence of power functions with rational exponents, different from the parent exponents of<i> α</i> = 3 and <i>α</i> = 1 occur. Each power function holds over a finite temperature range. A change of the exponent is a typical crossover event. From analyses of available experimental heat capacity data, the exponents of <i>α</i> = 1/2, 1, 3/2, 2, 3 and 4 could firmly be established. As the zero-field heat capacity of all superconductors, the critical field of the type I superconductors, <i>B</i>_C(T), exhibits critical behavior at <i>T</i> = 0 only but not at the transition temperature, <i>T</i>_SC. The superconducting transition, therefore, is not into a long-range ordered state. For all type I superconductors the critical exponent of <i>B</i>_C(<i>T</i>) at <i>T</i> = 0 seems to be <i>ε</i> = 2. The lower and upper critical fields, <i>B</i>_C1(<i>T</i>) and <i>B</i>_C2(<i>T</i>), of the type II superconductors exhibit critical behavior not only at <i>T</i> = 0 but additionally at T_SC, as it is common for long-range ordered systems. The experimentally identified critical exponents at <i>T</i> = 0 are <i>ε</i> = 3/2, 4/2, 5/2, 6/2 and 8/2. At <i>T</i> = <i>T</i>_SC, the identified critical exponents are <i>β</i> = 2/3, 3/4 and 1. The large <i>B</i>_C1 and <i>B</i>_C2 values indicate that the two Cooper-pair electrons of the type II superconductors are much stronger coupled compared to the type I superconductors, remarkably, without a corresponding increase in <i>T</i>_SC. The diameter of the Cooper pairs of the type II superconductors and, therefore, their diamagnetic moments are correspondingly low. At the critical field <i>B</i>_C1, the diamagnetic moment of the individual Cooper-pair is no longer large enough such that only one layer of Cooper pairs next to the inner surface of the sample is sufficient to shield an applied magnetic field completely. The external field then penetrates the superconductor as an ordered flux-line lattice. As the critical behavior of <i>B</i>_C1 and <i>B</i>_C2 at <i>T</i>_SC suggest, the flux-line lattice has the character of a long-range ordered system.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"51 - 69"},"PeriodicalIF":2.0,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4745364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrostatic Pressure Effect on the Thermodynamic Properties of Quantum Wire Under a Crossed Electromagnetic Field","authors":"Pranay Khosla,&nbsp;Sakshi Arora,&nbsp;Yash Gupta,&nbsp; Priyanka,&nbsp;Rinku Sharma","doi":"10.1007/s10909-023-02990-2","DOIUrl":"10.1007/s10909-023-02990-2","url":null,"abstract":"<div><p>In this paper, a GaAs quantum wire is considered with a semi-parabolic lateral confinement potential in the presence of a crossed electromagnetic field with the inclusion of Rashba SOI. The effects of pressure on thermodynamic properties have been studied. To this end, first, the eigenenergies for the system have been calculated considering Rashba spin effects under electric and magnetic fields. Then a numerical analysis is done to derive the partition function and obtain the system's thermodynamic properties. The results show that at low temperatures, all four thermodynamic properties don’t show much effect due to pressure. It is found that entropy increases with increasing hydrostatic pressure, whereas pressure affects mean energy and free energy in a different manner. A peak structure is observed in specific heat as a function of temperature where the peak position depends on hydrostatic pressure.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"92 - 106"},"PeriodicalIF":2.0,"publicationDate":"2023-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-023-02990-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4484349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strain Measurement Method Based on External Symmetrical Compensation Bridge Composed of Strain Gauges with Four-Wire Configuration for a Large-Scale NbTi Superconducting Dipole Magnet Detector","authors":"Yongjie Zhang,&nbsp;Canjie Xin,&nbsp;Peifeng Gao,&nbsp;Tianhu He,&nbsp;Mingzhi Guan","doi":"10.1007/s10909-023-02989-9","DOIUrl":"10.1007/s10909-023-02989-9","url":null,"abstract":"<div><p>This study presents a new strain measurement method based on an external symmetrical compensation bridge (ESCB) composed of strain gauges with a four-wire configuration. Unlike the traditional strain measurement methods, this method includes two features: first, utilising the four-wire configuration to eliminate measurement errors that occur due to large space-varying thermal and field imbalances of long signal wires during operation, and second, utilising two independent quarter-active sub-bridges with a four-wire configuration composed of ESCB to eliminate the errors that occur due to the large time-varying cryogenic temperature and magnetic field. This method was validated and used on a large-scale NbTi superconducting dipole magnet detector during the cooling, excitation, and quench tests. The strains measured using the ESCB were also compared with those measured using a traditional half-active compensation bridge. The observations showed that the ESCB method can overcome the interference of the temperature gradient and electromagnetic field of long wires during both cooling and electromagnetic excitation processes. In addition to the abrupt strain signal appearing when a quench occurred, high amplitudes occurring at high frequencies were observed at the onset of a quench based on the strain spectra analysis. Thus, the strain spectra are expected to provide a novel means for early quench warning.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"121 - 137"},"PeriodicalIF":2.0,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5177312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kelvin Waves, Mutual Friction, and Fluctuations in the Gross–Pitaevskii Model","authors":"Giorgio Krstulovic,&nbsp;Marc E. Brachet","doi":"10.1007/s10909-023-02985-z","DOIUrl":"10.1007/s10909-023-02985-z","url":null,"abstract":"<div><p>In this work, we first briefly review some of the mutual friction effects on vortex lines and rings that were obtained in the context of the truncated Gross–Pitaevskii equation in references Krstulovic and Brachet (Phys Rev E 83(6):066311, 2011; Phys Rev B 83:132506, 2011), with particular attention to the anomalous slowdown of rings produced by thermally excited Kelvin waves. We then study the effect of mutual friction on the relaxation and fluctuations of Kelvin waves on straight vortex lines by comparing the results of full 3D direct simulations of the truncated Gross–Pitaevskii equation with a simple stochastic Local-Induction-Approximation model with mutual friction and thermal noise included. This new model allows us to determine the mutual friction coefficient <span>(varvec{alpha })</span> and <span>(varvec{alpha '})</span> for the truncated Gross–Pitaevskii equation.\u0000</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"212 5-6","pages":"321 - 341"},"PeriodicalIF":2.0,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-023-02985-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5083005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial for the Special Issue in Honor of Joe Vinen","authors":"Carlo F. Barenghi,&nbsp;Ladislav Skrbek","doi":"10.1007/s10909-023-02988-w","DOIUrl":"10.1007/s10909-023-02988-w","url":null,"abstract":"","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"212 5-6","pages":"153 - 154"},"PeriodicalIF":2.0,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5083004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimized Cryogenic FBG Sensitivity Coefficient Calibration for High-Precision Thermal Expansion Measurements","authors":"Taolue Yang,&nbsp;Shi Liu,&nbsp;Yi Yang,&nbsp;Xinran Guo,&nbsp;Tao Tao","doi":"10.1007/s10909-023-02980-4","DOIUrl":"10.1007/s10909-023-02980-4","url":null,"abstract":"<div><p>Under conventional temperature regimes, optical fiber sensors (OFS) have been extensively utilized for real-time monitoring of strain and temperature responses in transportation, energy, and civil engineering structures. However, in low-temperature environments, OFS applications confront challenges such as poor adhesion, diminished sensitivity, weak signal transmission, and complex compensation requirements. Therefore, it is crucial to conduct in-depth research on the high-precision calibration characteristics of strain and temperature in cryogenic conditions. In this study, we propose an enhanced calibration technique for fiber Bragg grating (FBG) strain/temperature sensitivity, covering a low-temperature range of 77–296 K. Employing a custom-designed low-temperature testing apparatus, we calibrated the thermo-optic coefficients, temperature, and strain sensitivity coefficients. Subsequently, this improved method was applied to measure the coefficient of thermal expansion of various materials. The results confirm the accuracy of the proposed method and present the strain/temperature measurement properties of FBG. This research provides guidance for the precise use of FBG in low-temperature environments.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"107 - 120"},"PeriodicalIF":2.0,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5346582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scattering- and Binding Properties of Two 133Cs Atoms in Free Space and in an Ultracold, Low-Dense 133Cs Vapor","authors":"Humam B. Ghassib,&nbsp;Ahmad M. Alkurdi,&nbsp;Ayman S. Sandouqa","doi":"10.1007/s10909-023-02987-x","DOIUrl":"10.1007/s10909-023-02987-x","url":null,"abstract":"<div><p>The scattering- and bound-state properties of two ¹³³Cs atoms, in free space as well as in low-dense Cs vapor, are calculated for both electronic singlet and triplet states. In free space, standard scattering theory is used; specifically, the Lippmann–Schwinger t-matrix equation is solved by a matrix-inversion technique. The output is the phase shifts, from which the corresponding (total, viscosity, [complex] spin-exchange, and average) cross sections are computed. In the vapor, a generalized scattering theory is invoked, the key equation being the Galitskii–Migdal–Feynman T-matrix equation. This is solved by the same technique to obtain the cross sections in the <i>medium</i>. Likewise, the t- and T-matrix equations are solved for negative definite energy eigenvalues—again, by matrix inversion, albeit after symmetrizing the kernel in the integral equation involved—to determine the respective binding energies of the Cs₂ dimer in free space and in the vapor. Sharp resonance peaks, representing ‘quasi’ bound states, appear in the cross sections. In the triplet total and viscosity cross sections, quantum effects appear as undulations. The results obtained for the complex spin-exchange cross sections are particularly highlighted, because of their importance in the spectroscopy of the ¹³³Cs₂ dimer. So are the results for the binding energy of this dimer, which are important in the physics of ultracold molecules. In calculating this quantity, as many relative partial waves as necessary (<i>ℓ</i> = 0–7 and 0–8 in free space and the medium, respectively) are taken into account to guarantee ‘convergence’. The role of the medium is given special attention throughout. Most of the quantities considered here are calculated for the first time; but whenever available, comparison is made with previous results.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"1 - 27"},"PeriodicalIF":2.0,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-023-02987-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4825291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Entanglement Generated in Quantum Dot-Cavity Coupled System Mediated by Plasmonic Waveguide","authors":"Ju-Song Ryom,&nbsp;Gang-Yong Ri,&nbsp;Nam-Chol Kim,&nbsp;Myong-Chol Ko,&nbsp;Il-Hyang Choe,&nbsp;Su-Ryon Ri","doi":"10.1007/s10909-023-02982-2","DOIUrl":"10.1007/s10909-023-02982-2","url":null,"abstract":"<div><p>We theoretically study the entanglement between two quantum dots (QDs) with dipole–dipole interaction (DDI) in the composite quantum system composed of a plasmonic waveguide and two cavities. The analytical expressions of the pairwise concurrence as a measure of entanglement are obtained by determining the excitation probability amplitudes with real space formalism. The properties of the entanglement are discussed in detail under the control of physical parameters such as detuning and coupling strengths. We demonstrate the DDI can improve the entanglement in short distance and highly entangled states can be obtained in the cases of symmetric and asymmetric coupling.\u0000</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"213 1-2","pages":"80 - 91"},"PeriodicalIF":2.0,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4828766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}