Journal of Low Temperature Physics最新文献

{"title":"Longitudinal Spin Response and Amplitude Fluctuations in the Triangular-Lattice Hubbard Antiferromagnet","authors":"Saptarshi Ghosh","doi":"10.1007/s10909-026-03472-x","DOIUrl":"10.1007/s10909-026-03472-x","url":null,"abstract":"<div><p>We investigate the momentum- and frequency-resolved longitudinal spin response of the half-filled triangular-lattice Hubbard model in the <span>(120^circ )</span> antiferromagnetically ordered state. Using a spiral Hartree–Fock (HF) reference state and the random-phase approximation (RPA), we calculate the longitudinal spectral function <span>(S_L(textbf{q},omega )=-(1/pi )operatorname {Im}chi _L^R(textbf{q},omega ))</span> along the high-symmetry path <span>(Gamma rightarrow Krightarrow Mrightarrow Gamma )</span> for <span>(U/t=6)</span>, 8, and 10. In contrast to the coherent transverse Goldstone sector, the longitudinal response forms a broad high-energy continuum with momentum-dependent ridge-like enhancements that remain embedded in the interband particle–hole spectrum. Full-spectrum moment analysis yields centroid ranges <span>(omega _L^textrm{cen}/tsimeq 5.9)</span>–6.7, 7.9–8.5, and 9.9–10.4 for <span>(U/t=6)</span>, 8, and 10, respectively, demonstrating a systematic upward shift of the characteristic longitudinal energy scale with increasing interaction strength. The corresponding second-moment spectral width remains large and strongly momentum dependent, with a broad maximum <span>(Gamma _L/tsimeq 3.2)</span>–3.3 near <i>K</i>, and does not exhibit a uniform narrowing with increasing <i>U</i>/<i>t</i>. Fixed-momentum cuts further reveal distinct longitudinal structures at <i>K</i> and <i>M</i>, with principal enhancements near <span>(omega /tsimeq 4.8)</span> and 7.2, respectively, at <span>(U/t=8)</span>. Within HF+RPA, the broad response originates from direct coupling of longitudinal amplitude fluctuations to interband particle–hole excitations in the electronic Stoner continuum, which prevents the formation of an isolated amplitude-mode pole. With increasing <i>U</i>/<i>t</i>, this high-energy Stoner sector is displaced upward and progressively separates from the low-energy spin sector; it should not be identified with the longitudinal response of the localized-spin Heisenberg model, which arises from multi-magnon processes beyond the present treatment. These results provide a finite-<i>U</i> itinerant description of longitudinal amplitude fluctuations as broad continuum responses rather than well-defined Higgs quasiparticles in the triangular-lattice Hubbard antiferromagnet.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132081","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":"Magneto–Mechanical Coupling Analysis of REBCO Superconducting Coils After Quench Protection","authors":"Zhilue Zeng,&nbsp;Ruoshan Jiao,&nbsp;Yongjie Zhang,&nbsp;Junjie Du,&nbsp;Mingzhi Guan","doi":"10.1007/s10909-026-03466-9","DOIUrl":"10.1007/s10909-026-03466-9","url":null,"abstract":"<div><p>Based on Maxwell’s equations, the heat conduction equation, and basic equations of elasticity, a two-dimensional (2D) axisymmetric coupled thermal–magneto–mechanical model for an insulated pancake coil with real dimensions is constructed and theoretically validated in a rigorous manner. Using finite element modeling, the effects of the system dump trigger time and background magnetic field on the quench behaviors of a high-temperature superconducting (HTS)-insulated pancake coil are systematically studied. To analyze the electromagnetic and mechanical behaviors of HTS coils, a 2D coupled electromagnetic–mechanical model is used to incorporate the effect of coil deformation on the critical current dependence. The effectiveness of the coupled model is validated by comparing the numerical results with published experimental data. Numerical simulations of a 2D HTS coil under an external electromagnetic field are performed using the fully coupled and sequentially coupled methods, respectively. The results indicate that increasing the time taken to trigger the system dump has no influence on the energy dissipation rate. Compared with sequential coupling, the maximum temperature of the coil increases significantly under the fully coupled formulation, and the maximum value is achieved at an earlier time. An apparent slope change in the radial strain rate is observed when the quench occurs, regardless of the magnitude of the background magnetic field. Under full coupling, the radial strain rate increases slightly, reaches its maximum value earlier, and then begins to decrease. During quench protection, the radial stress and strain reach their maximum values and then decrease as the temperature decreases. Under full coupling, the stress and strain reach their maximum values at a faster rate.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149034732","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":"Josephson Oscillations of Bose-Einstein Condensate in Double-Well Potential: Two-Mode Model and Beyond","authors":"Haoyu Wang,&nbsp;Guangyu Liu,&nbsp;Lizhen Sun,&nbsp;Haibin Li","doi":"10.1007/s10909-026-03465-w","DOIUrl":"10.1007/s10909-026-03465-w","url":null,"abstract":"<div><p>The Josephson oscillation of a Bose-Einstein condensate (BEC) in a double-well potential is typically characterized by the population imbalance between the two wells. Within the two-mode approximation, the dynamics of the center of mass of the condensate is predicted to coincide with that of the population imbalance. However, numerical simulations reveal a discrepancy between the dynamics of the center of mass and that of the population imbalance, indicating that the two-mode model fails to fully capture the dynamics of BEC Josephson oscillations. To address this limitation, a four-mode approximation is employed to describe the dynamics of the system. The four-mode model not only describes the dynamics of the population imbalance but also accounts for the oscillation of the center of mass, thereby explaining the origin of the discrepancy between the two-mode model and the simulation results. Moreover, we find that although higher-order excitation modes are always present in Josephson oscillations, the two-mode model can still describe the dynamics of the population imbalance. This phenomenon is explained by the interference of population oscillations between local states.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148986777","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":"Luttinger Liquid with One Impurity: Duality, Universality and Qualitative Description of the Phenomenon","authors":"V. V. Afonin","doi":"10.1007/s10909-026-03463-y","DOIUrl":"10.1007/s10909-026-03463-y","url":null,"abstract":"<div><p>A new approach describing Luttinger Liquid with point-like impurity as field theory for the phase of scattering is developed. It is based on a matching of the electron wave functions at an impurity position point. As a result of the approach, an expression for non-local action has been taken. The non-locality of the theory leads to the convergence of the observed values in an ultraviolet region. It allows studying conductance of the channel up to electron–electron interaction strength of the order of unit. Expansion of the non-local action in small frequency powers makes possible to develop a new approach to the renormalization group analysis of the problem. This method differs from the “poor man’s” approach widely used in solid-state physics. We have shown, that in the Luttinger liquid “poor man’s” approach breaks already in two-loop approximation. We analyse the reason of this discrepancy. The qualitative description of the phenomenon is discussed in detail.\u0000</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148986776","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":"Quantum Transport in the (alpha )-(mathcal {T}_3) Model with a Fermi Velocity Barrier","authors":"Niao Bo,&nbsp;Jun-Tong Ren,&nbsp;Tian-Hao Ren,&nbsp;Hai-Feng Lü","doi":"10.1007/s10909-026-03462-z","DOIUrl":"10.1007/s10909-026-03462-z","url":null,"abstract":"<div><p>We investigate the quantum transport through a rectangular velocity barrier in the <span>(alpha )</span>-<span>(mathcal {T}_3)</span> lattice. The scattering states are solved analytically, and the transport properties including conductance, shot noise, and Fano factor are obtained by following the zero-temperature Landauer–Büttiker formalism. The velocity mismatch across the barrier reshapes oblique tunneling channels while preserving the perfect transmission at normal incidence. In particular, this velocity mismatch shifts the critical incident energy for super-Klein tunneling, where transport becomes nearly noiseless as the conductance approaches unity. At the Dirac point, the velocity modulation leaves the finite conductance minimum of the honeycomb limit intact, accompanied by a universal Fano factor peak. In the dice limit, however, both conductance and shot noise vanish at this point owing to channel depletion. In addition, a slow barrier facilitates the high-energy transport for the dice lattice, while a fast barrier can suppress it in both lattice limits.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926761","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":"Phase-Sensitive Cascade Quantum Amplifier with Nearly Noiseless Operation","authors":"Ilari Lilja,&nbsp;Ekaterina Mukhanova,&nbsp;Michael Perelshtein,&nbsp;Kirill Petrovnin,&nbsp;Stanislav Khaldeev,&nbsp;Visa Vesterinen,&nbsp;Gheorghe-Sorin Paraoanu,&nbsp;Pertti Hakonen","doi":"10.1007/s10909-026-03458-9","DOIUrl":"10.1007/s10909-026-03458-9","url":null,"abstract":"<div><p>Phase-sensitive parametric devices facilitate quadrature-selective amplification with the possibility for sub-quantum-limited noise performance. In this work, we investigate the operation of a SQUID-based Josephson parametric amplifier (JPA), comparing its gain and noise performance in the phase-preserving and phase-sensitive regimes. The device, fabricated using VTT SWAPS technology, is driven in a three-wave mixing configuration and characterized in a reflection-based measurement setup at millikelvin temperatures. To directly probe the noise performance at low JPA gains, we employ a cascaded amplification scheme in which a traveling-wave parametric amplifier (TWPA) provides low-noise preamplification of the JPA output. In a phase-preserving operation, the JPA exhibits near-quantum-limited performance with a system noise temperature of <span>(351pm 53)</span> mK at 6 GHz. In contrast, phase-sensitive operation yields a minimum system noise temperature of <span>(94pm 12)</span> mK, well below the standard quantum limit of 288 mK. Our results demonstrate that a JPA–TWPA amplifier cascade opens the door to direct, high-fidelity probing of quantum devices without the need for background noise subtraction.\u0000</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-026-03458-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926446","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":"Design, Fabrication, and Characterization of Microwave Multiplexing SQUID Prototype","authors":"Mengjie Song,&nbsp;Yixian Deng,&nbsp;Zhengwei Li,&nbsp;He Gao,&nbsp;Zhouhui Liu,&nbsp;Yudong Gu,&nbsp;XiangXiang Ren,&nbsp;Nan Li,&nbsp;Guofu Liao,&nbsp;Qinglei Xiu,&nbsp;Yu Xu,&nbsp;Mengqi Jiang,&nbsp;Xufang Li,&nbsp;Yaqiong Li,&nbsp;Shibo Shu,&nbsp;Yongjie Zhang,&nbsp;Congzhan Liu","doi":"10.1007/s10909-026-03461-0","DOIUrl":"10.1007/s10909-026-03461-0","url":null,"abstract":"<div><p>The readout system with a high multiplexing ratio has become a bottleneck limiting the application of large-scale transition-edge sensor (TES) detector arrays. In recent years, the microwave superconducting quantum interference device (SQUID) multiplexer has emerged as a key technology for effectively reading large-scale cryogenic detector arrays. Currently, the microwave SQUID multiplexer is being adopted by an increasing number of experiments due to its capability of achieving a multiplexing ratio of 2000:1 within the readout bandwidth. In this study, we developed a 32-channel microwave SQUID multiplexer prototype. And we measured eight channels of the prototype. The measured equivalent noise current of the prototype reached 42 pA/<span>(sqrt{Hz})</span>.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148783001","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":"Cusped Electrical Conductivity in Spin-1 Chiral Fermion Systems Arising from Multifold Band Degeneracy","authors":"Risako Kikuchi,&nbsp;Junya Endo,&nbsp;Ai Yamakage","doi":"10.1007/s10909-026-03448-x","DOIUrl":"10.1007/s10909-026-03448-x","url":null,"abstract":"<div><p>The energy-dependent electrical conductivity in spin-1 chiral fermion systems with disorder is studied using the self-consistent Born approximation. A distinct cusp-like feature appears at an energy different from the band-crossing point, arising from the multifold band-crossing structure formed by the Dirac and trivial bands. By decomposing the conductivity into band-resolved intraband and interband contributions, we clarify the microscopic origin of the cusp structure previously identified in spin-1 chiral fermion systems. These findings demonstrate the critical role of multifold band crossings and disorder-induced broadening of energy levels in determining the transport properties, offering theoretical insight into the unconventional conductivity behavior observed in topological semimetals hosting spin-1 chiral fermions.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782855","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":"Correction: Absence of a Phase-Inversion Center as a Necessary Condition for the Josephson Diode Effect and Application to Strongly Spin-Polarized Magnets","authors":"Danilo Nikolić,&nbsp;Niklas L. Schulz,&nbsp;Matthias Eschrig","doi":"10.1007/s10909-026-03446-z","DOIUrl":"10.1007/s10909-026-03446-z","url":null,"abstract":"","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782317","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":"Solid Argon Films Under Nonequilibrium Conditions","authors":"Paul Leiderer","doi":"10.1007/s10909-026-03460-1","DOIUrl":"10.1007/s10909-026-03460-1","url":null,"abstract":"<div><p>Argon belongs to the class of rare and molecular gases that exhibit triple-point wetting, a regime in which adsorbed solid films remain only a few monolayers thick under thermodynamic equilibrium well below the triple point. Here we investigate the behavior of such films under nonequilibrium conditions, with particular emphasis on temperature gradients imposed within the sample cell. We show that these gradients can drive the formation of significantly thicker films than predicted by triple-point wetting theory. Our findings are motivated by, and possibly offer insight into, recent experiments with electron qubits above solid neon films, where film thicknesses substantially exceed equilibrium expectations.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 5","pages":""},"PeriodicalIF":1.2,"publicationDate":"2026-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-026-03460-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719163","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}