| 1. |
- Cayao, Jorge, PhD, 1986-, et al.
(författare)
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Controllable odd-frequency Cooper pairs in multisuperconductor Josephson junctions
- 2024
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 109:20
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Tidskriftsartikel (refereegranskat)abstract
- We consider Josephson junctions formed by multiple superconductors with distinct phases and explore the formation of nonlocal or intersuperconductor pair correlations. We find that the multiple superconductor nature offers an additional degree of freedom that broadens the classification of pair symmetries, enabling nonlocal evenand odd -frequency pairings that can be highly controlled by the superconducting phases and the energy of the superconductors. Specially, when the phase difference between two superconductors is n , their associated nonlocal odd -frequency pairing is the only type of intersuperconductor pair correlations. Finally, we show that these nonlocal odd -frequency Cooper pairs dominate the nonlocal conductance via crossed Andreev reflections, which constitutes a direct evidence of odd -frequency pairing.
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| 2. |
- Cayao, Jorge, PhD, 1986-, et al.
(författare)
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Enhancing the Josephson diode effect with Majorana bound states
- 2024
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 109:8
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Tidskriftsartikel (refereegranskat)abstract
- We consider phase-biased Josephson junctions with spin-orbit coupling under external magnetic fields and study the emergence of the Josephson diode effect in the presence of Majorana bound states. We show that junctions having middle regions with Zeeman fields along the spin-orbit axis develop a low-energy Andreev spectrum that is asymmetric with respect to the superconducting phase difference ϕ = π, which is strongly influenced by Majorana bound states in the topological phase. This asymmetric Andreev spectrum gives rise to anomalous current-phase curves and critical currents that are different for positive and negative supercurrents, thus signaling the emergence of the Josephson diode effect. While this effect exists even in the trivial phase, it gets enhanced in the topological phase due to the spatial nonlocality of Majorana bound states. Our paper thus establishes the utilization of topological superconductivity for enhancing the functionalities of Josephson diodes.
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| 3. |
- Nakosai, Sho, et al.
(författare)
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Majorana Bound States and Nonlocal Spin Correlations in a Quantum Wire on an Unconventional Superconductor
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:11, s. 117002-
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Tidskriftsartikel (refereegranskat)abstract
- We study theoretically the proximity effect of a one-dimensional metallic quantum wire (in the absence of spin-orbit interaction) lying on top of an unconventional superconductor. Three different material classes are considered as a substrate: (i) a chiral superconductor in class D with broken time-reversal symmetry and a class DIII superconductor (ii) with and (iii) without a nontrivial Z(2) number. Interestingly, we find degenerate zero energy Majorana bound states at both ends of the wire for all three cases. They are unstable against spin-orbit interaction in case (i), while they are topologically protected by time-reversal symmetry in cases (ii) and (iii). Remarkably, we show that nonlocal spin correlations between the two ends of the wire can be simply controlled by a gate potential in our setup. DOI: 10.1103/PhysRevLett.110.117002
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| 4. |
- Oshima, Toshinori, et al.
(författare)
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Changes in pathological and biochemical findings of systemic tissue sites in familial amyloid polyneuropathy more than 10 years after liver transplantation
- 2014
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Ingår i: Journal of Neurology, Neurosurgery and Psychiatry. - : BMJ. - 0022-3050 .- 1468-330X. ; 85:7, s. 740-746
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Tidskriftsartikel (refereegranskat)abstract
- Objective To elucidate the long-term effects of liver transplantation (LT) on familial amyloid polyneuropathy (FAP). Methods We investigated clinicopathological and biochemical characteristics of systemic tissues in four autopsied cases of FAP patients surviving more than 10 years after LT and seven autopsied cases without LT. For analysing the truncated form of transthyretin (TTR) in amyloid, we also employed specimens from additional 18 FAP patients. Results Several tissue sites such as the heart, tongue and spinal cord had moderate-to-severe amyloid deposits but other tissues showed no or mild amyloid deposition. Those findings seemed similar to those observed in senile systemic amyloidosis (SSA), a sporadic amyloidosis caused by wild-type (WT) TTR. Also, amyloid deposits in systemic tissue sites except for the spinal cord in patients after LT derived mostly from WT TTR secreted from the normal liver grafts. In addition, in non-transplantation patients, proportions of WT TTR seemed to be relatively high in those tissue sites in which patients after LT had severe amyloid deposition, which suggests that WT TTR tends to form amyloid in those tissue sites. Finally, although the truncation of TTR in amyloid deposits did not depend on undergoing LT, we elucidated the truncation of TTR occurred predominantly in patients from non-endemic areas of Japan, where FAP amyloidogenic TTR V30M patients are late onset and low penetrance, compared with patients from an endemic area of Japan. Conclusions FAP may shift to systemic WT TTR amyloid formation after LT, which seems to be similar to the process in SSA. The truncation of TTR in amyloid deposits may depend on some genetic or environmental factors other than undergoing LT.
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| 5. |
- Tamura, Shun, et al.
(författare)
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Bulk odd-frequency pairing in the superconducting Su-Schrieffer-Heeger model
- 2020
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Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 101:21
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Tidskriftsartikel (refereegranskat)abstract
- The Su-Schrieffer-Heeger model describes fermions that hop on a one-dimensional chain with staggered hopping amplitude, where the unit cell contains two sites, or two sublattices. In this work we consider the Su-Schrieffer-Heeger model with superconducting pairing and show that the sublattice index acts as an additional quantum number in the classification of Cooper pairs, giving rise to inter- and intrasublattice odd-frequency pair correlations in the bulk. Interestingly, this system behaves as a two-band superconductor where the bulk odd-frequency correlations depend solely on the intrinsic staggering properties of the model. In general, odd-frequency correlations coexist with even-frequency correlations in both the trivial and topological phases, with comparable and even larger odd-frequency amplitudes at the topological phase transition points at low frequencies, due to the closing of the energy gap at these points. Furthermore, we also discuss how bulk odd-frequency amplitudes are correlated with pseudogaps in the density of states and also with a charge density wave that appears due to the chemical potential imbalance between sublattices.
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| 6. |
- Yabuta, Hikaru, et al.
(författare)
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Macromolecular organic matter in samples of the asteroid (162173) Ryugu
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 379:6634
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Tidskriftsartikel (refereegranskat)abstract
- Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugus parent body.
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| 7. |
- Zhang, Cheng, et al.
(författare)
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A Monte Carlo based computation offloading algorithm for feeding robot IoT system
- 2018
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Ingår i: Smart Computing and Communication. - Cham : Springer. - 9783030057541 ; , s. 163-171
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Konferensbidrag (refereegranskat)abstract
- Ageing is becoming an increasingly major problem in European and Japanese societies. We have so far mainly focused on how to improve the eating experience for both frail elderly and caregivers by introducing and developing the eating aid robot, Bestic, made to get the food from plate to the mouth for frail elderly or person with disabilities. We expand the functionalities of Bestic to create food intake reports automatically so as to decrease the undernutrition among frail elderly and workload of caregivers through collecting data via a vision system connected to the Internet of Things (IoT) system. Since the computation capability of Bestic is very limited, computation offloading, in which resource intensive computational tasks are transferred from Bestic to an external cloud server, is proposed to solve Bestic’s resource limitation. In this paper, we proposed a Monte Carlo algorithm based heuristic computation offloading algorithm, to minimize the total overhead of all the Bestic users after we show that the target optimization problem is NP-hard in a theorem. Numeric results showed that the proposed algorithm is effective in terms of system-wide overhead.
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