Ning Wang, Shao-Min Wang, Run-Ze Zhang, Jia-Min Kang, Wen-Long Lu, Hai-Ou Li, Gang Cao, Bao-Chuan Wang, Guo-Ping Guo
Electron spin qubits in silicon are a promising platform for fault-tolerant quantum computing. Low-frequency noise, including nuclear spin fluctuations and charge noise, is a primary factor limiting gate fidelities. Suppressing this noise is crucial for high-fidelity qubit operations. Here, we report on a two-qubit quantum device in natural silicon with universal qubit control, designed to investigate the upper limits of gate fidelities in a non-purified Si/SiGe quantum dot device. By employing advanced device structures, qubit manipulation techniques, and optimization methods, we have achieved single-qubit gate fidelities exceeding 99% and a two-qubit Controlled-Z (CZ) gate fidelity of 91%. Decoupled CZ gates are used to prepare Bell states with a fidelity of 91%, typically exceeding previously reported values in natural silicon devices. These results underscore that even natural silicon has the potential to achieve high-fidelity gate operations, particularly with further optimization methods to suppress low-frequency noise.
{"title":"Pursuing high-fidelity control of spin qubits in natural Si/SiGe quantum dot","authors":"Ning Wang, Shao-Min Wang, Run-Ze Zhang, Jia-Min Kang, Wen-Long Lu, Hai-Ou Li, Gang Cao, Bao-Chuan Wang, Guo-Ping Guo","doi":"arxiv-2409.09747","DOIUrl":"https://doi.org/arxiv-2409.09747","url":null,"abstract":"Electron spin qubits in silicon are a promising platform for fault-tolerant\u0000quantum computing. Low-frequency noise, including nuclear spin fluctuations and\u0000charge noise, is a primary factor limiting gate fidelities. Suppressing this\u0000noise is crucial for high-fidelity qubit operations. Here, we report on a\u0000two-qubit quantum device in natural silicon with universal qubit control,\u0000designed to investigate the upper limits of gate fidelities in a non-purified\u0000Si/SiGe quantum dot device. By employing advanced device structures, qubit\u0000manipulation techniques, and optimization methods, we have achieved\u0000single-qubit gate fidelities exceeding 99% and a two-qubit Controlled-Z (CZ)\u0000gate fidelity of 91%. Decoupled CZ gates are used to prepare Bell states with a\u0000fidelity of 91%, typically exceeding previously reported values in natural\u0000silicon devices. These results underscore that even natural silicon has the\u0000potential to achieve high-fidelity gate operations, particularly with further\u0000optimization methods to suppress low-frequency noise.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ravi Kumar, Saurabh Kumar Srivastav, Ujjal Roy, Ujjawal Singhal, K. Watanabe, T. Taniguchi, Vibhor Singh, P. Roulleau, Anindya Das
The charge neutrality point of bilayer graphene, denoted as {nu} = 0 state, manifests competing phases marked by spontaneously broken isospin (spin/valley/layer) symmetries under external magnetic and electric fields. However, due to their electrically insulating nature, identifying these phases through electrical conductance measurements remains challenging. A recent theoretical proposal introduces a novel approach, employing thermal transport measurements to detect these competing phases. Here, we experimentally explore the bulk thermal transport of the {nu} = 0 state in bilayer graphene to investigate its ground states and collective excitations associated with isospin. While the theory anticipates a finite thermal conductance in the {nu} = 0 state, our findings unveil an absence of detectable thermal conductance. Through variations in the external electric field and temperature-dependent measurements, our results suggest towards gapped collective excitations at {nu} = 0 state. Our findings underscore the necessity for further investigations into the nature of {nu} = 0.
{"title":"Absence of heat flow in ν = 0 quantum Hall ferromagnet in bilayer graphene","authors":"Ravi Kumar, Saurabh Kumar Srivastav, Ujjal Roy, Ujjawal Singhal, K. Watanabe, T. Taniguchi, Vibhor Singh, P. Roulleau, Anindya Das","doi":"arxiv-2409.09663","DOIUrl":"https://doi.org/arxiv-2409.09663","url":null,"abstract":"The charge neutrality point of bilayer graphene, denoted as {nu} = 0 state,\u0000manifests competing phases marked by spontaneously broken isospin\u0000(spin/valley/layer) symmetries under external magnetic and electric fields.\u0000However, due to their electrically insulating nature, identifying these phases\u0000through electrical conductance measurements remains challenging. A recent\u0000theoretical proposal introduces a novel approach, employing thermal transport\u0000measurements to detect these competing phases. Here, we experimentally explore\u0000the bulk thermal transport of the {nu} = 0 state in bilayer graphene to\u0000investigate its ground states and collective excitations associated with\u0000isospin. While the theory anticipates a finite thermal conductance in the {nu}\u0000= 0 state, our findings unveil an absence of detectable thermal conductance.\u0000Through variations in the external electric field and temperature-dependent\u0000measurements, our results suggest towards gapped collective excitations at\u0000{nu} = 0 state. Our findings underscore the necessity for further\u0000investigations into the nature of {nu} = 0.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ning Wang, Jia-Min Kang, Wen-Long Lu, Shao-Min Wang, You-Jia Wang, Hai-Ou Li, Gang Cao, Bao-Chuan Wang, Guo-Ping Guo
Scaling up quantum dots to two-dimensional (2D) arrays is a crucial step for advancing semiconductor quantum computation. However, maintaining excellent tunability of quantum dot parameters, including both nearest-neighbor and next-nearest-neighbor couplings, during 2D scaling is challenging, particularly for silicon quantum dots due to their relatively small size. Here, we present a highly controllable and interconnected 2D quantum dot array in planar silicon, demonstrating independent control over electron fillings and the tunnel couplings of nearest-neighbor dots. More importantly, we also demonstrate the wide tuning of tunnel couplings between next-nearest-neighbor dots,which plays a crucial role in 2D quantum dot arrays. This excellent tunability enables us to alter the coupling configuration of the array as needed. These results open up the possibility of utilizing silicon quantum dot arrays as versatile platforms for quantum computing and quantum simulation.
{"title":"Highly tunable 2D silicon quantum dot array with coupling beyond nearest neighbors","authors":"Ning Wang, Jia-Min Kang, Wen-Long Lu, Shao-Min Wang, You-Jia Wang, Hai-Ou Li, Gang Cao, Bao-Chuan Wang, Guo-Ping Guo","doi":"arxiv-2409.09761","DOIUrl":"https://doi.org/arxiv-2409.09761","url":null,"abstract":"Scaling up quantum dots to two-dimensional (2D) arrays is a crucial step for\u0000advancing semiconductor quantum computation. However, maintaining excellent\u0000tunability of quantum dot parameters, including both nearest-neighbor and\u0000next-nearest-neighbor couplings, during 2D scaling is challenging, particularly\u0000for silicon quantum dots due to their relatively small size. Here, we present a\u0000highly controllable and interconnected 2D quantum dot array in planar silicon,\u0000demonstrating independent control over electron fillings and the tunnel\u0000couplings of nearest-neighbor dots. More importantly, we also demonstrate the\u0000wide tuning of tunnel couplings between next-nearest-neighbor dots,which plays\u0000a crucial role in 2D quantum dot arrays. This excellent tunability enables us\u0000to alter the coupling configuration of the array as needed. These results open\u0000up the possibility of utilizing silicon quantum dot arrays as versatile\u0000platforms for quantum computing and quantum simulation.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tongtong Zhang, Fuqiang Sun, Yaorong Wang, Yingchi Li, Jing Wang, Zhongqiang Wang, Kwai Hei Li, Ye Zhu, Qi Wang, Lei Shao, Ngai Wong, Dangyuan Lei, Yuan Lin, Zhiqin Chu
Diamond particles have many interesting properties and possible applications. However, producing diamond particles with well-defined shapes at scale is challenging because diamonds are chemically inert and extremely hard. Here, we show air oxidation, a routine method for purifying diamonds, can be used to precisely shape diamond particles at scale. By exploiting the distinct reactivities of different crystal facets and defects inside the diamond, layer-by-layer outward-to-inward and inward-to-outward oxidation produced diverse diamond shapes including sphere, twisted surface, pyramidal islands, inverted pyramids, nano-flowers, and hollow polygons. The nanosculpted diamonds had more and finer features that enabled them to outperform the original raw diamonds in various applications. Using experimental observations and Monte Carlo simulations, we built a shape library that guides the design and fabrication of diamond particles with well-defined shapes and functional value. Our study presents a simple, economical and scalable way to produce shape-customized diamonds for various photonics, catalysis, quantum and information technology applications.
{"title":"Scalable Reshaping of Diamond Particles via Programmable Nanosculpting","authors":"Tongtong Zhang, Fuqiang Sun, Yaorong Wang, Yingchi Li, Jing Wang, Zhongqiang Wang, Kwai Hei Li, Ye Zhu, Qi Wang, Lei Shao, Ngai Wong, Dangyuan Lei, Yuan Lin, Zhiqin Chu","doi":"arxiv-2409.09393","DOIUrl":"https://doi.org/arxiv-2409.09393","url":null,"abstract":"Diamond particles have many interesting properties and possible applications.\u0000However, producing diamond particles with well-defined shapes at scale is\u0000challenging because diamonds are chemically inert and extremely hard. Here, we\u0000show air oxidation, a routine method for purifying diamonds, can be used to\u0000precisely shape diamond particles at scale. By exploiting the distinct\u0000reactivities of different crystal facets and defects inside the diamond,\u0000layer-by-layer outward-to-inward and inward-to-outward oxidation produced\u0000diverse diamond shapes including sphere, twisted surface, pyramidal islands,\u0000inverted pyramids, nano-flowers, and hollow polygons. The nanosculpted diamonds\u0000had more and finer features that enabled them to outperform the original raw\u0000diamonds in various applications. Using experimental observations and Monte\u0000Carlo simulations, we built a shape library that guides the design and\u0000fabrication of diamond particles with well-defined shapes and functional value.\u0000Our study presents a simple, economical and scalable way to produce\u0000shape-customized diamonds for various photonics, catalysis, quantum and\u0000information technology applications.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"100 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The $z$-component of the N'{e}el vector is measurable by the anomalous Hall conductivity in altermagnets because time reversal symmetry is broken. On the other hand, it is a nontrivial problem how to measure the in-plane component of the N'{e}el vector. We study the second-order nonlinear conductivity of a system made of the $d$-wave altermagnet with the Rashba interaction. It is shown that the quantum-metric induced nonlinear conductivity and the nonlinear Drude conductivity are proportional to the in-plane component of the N'{e}el vector, and hence, the in-plane component of the N'{e}el vector is measurable. We obtain analytic formulas of the quantum-metric induced nonlinear conductivity and the nonlinear Drude conductivity both for the longitudinal and transverse conductivities. The quantum-metric induced nonlinear conductivity diverges at the Dirac point, while the nonlinear Drude conductivity is always finite. Hence, the quantum-metric induced nonlinear conductivity is dominant at the Dirac point irrespective of the relaxation time.
{"title":"Intrinsic nonlinear conductivity induced by quantum geometry in altermagnets and measurement of the in-plane Néel vector","authors":"Motohiko Ezawa","doi":"arxiv-2409.09241","DOIUrl":"https://doi.org/arxiv-2409.09241","url":null,"abstract":"The $z$-component of the N'{e}el vector is measurable by the anomalous Hall\u0000conductivity in altermagnets because time reversal symmetry is broken. On the\u0000other hand, it is a nontrivial problem how to measure the in-plane component of\u0000the N'{e}el vector. We study the second-order nonlinear conductivity of a\u0000system made of the $d$-wave altermagnet with the Rashba interaction. It is\u0000shown that the quantum-metric induced nonlinear conductivity and the nonlinear\u0000Drude conductivity are proportional to the in-plane component of the N'{e}el\u0000vector, and hence, the in-plane component of the N'{e}el vector is measurable.\u0000We obtain analytic formulas of the quantum-metric induced nonlinear\u0000conductivity and the nonlinear Drude conductivity both for the longitudinal and\u0000transverse conductivities. The quantum-metric induced nonlinear conductivity\u0000diverges at the Dirac point, while the nonlinear Drude conductivity is always\u0000finite. Hence, the quantum-metric induced nonlinear conductivity is dominant at\u0000the Dirac point irrespective of the relaxation time.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. L. Savchenko, D. A. Kozlov, S. S. Krishtopenko, N. N. Mikhailov, Z. D. Kvon, A. Pimenov, D. Weiss
The quantum Hall effect, which exhibits a number of unusual properties, is studied in a gated 1000-nm-thick HgTe film, nominally a three-dimensional system. A weak zero plateau of Hall resistance, accompanied by a relatively small value of Rxx of the order of h/e^2, is found around the point of charge neutrality. It is shown that the zero plateau is formed by the counter-propagating chiral electron-hole edge channels, the scattering between which is suppressed. So, phenomenologically, the quantum spin Hall effect is reproduced, but with preserved ballisticity on macroscopic scales (larger than 1mm). It is shown that the formation of the QHE occurs in a two-dimensional (2D) accumulation layer near the gate, while the bulk carriers play the role of an electron reservoir. Due to the exchange of carriers between the reservoir and the 2D layer, an anomalous scaling of the QHE is observed not with respect to the CNP, but with respect to the first electron plateau.
{"title":"Quantum Hall effect and zero plateau in bulk HgTe","authors":"M. L. Savchenko, D. A. Kozlov, S. S. Krishtopenko, N. N. Mikhailov, Z. D. Kvon, A. Pimenov, D. Weiss","doi":"arxiv-2409.09409","DOIUrl":"https://doi.org/arxiv-2409.09409","url":null,"abstract":"The quantum Hall effect, which exhibits a number of unusual properties, is\u0000studied in a gated 1000-nm-thick HgTe film, nominally a three-dimensional\u0000system. A weak zero plateau of Hall resistance, accompanied by a relatively\u0000small value of Rxx of the order of h/e^2, is found around the point of charge\u0000neutrality. It is shown that the zero plateau is formed by the\u0000counter-propagating chiral electron-hole edge channels, the scattering between\u0000which is suppressed. So, phenomenologically, the quantum spin Hall effect is\u0000reproduced, but with preserved ballisticity on macroscopic scales (larger than\u00001mm). It is shown that the formation of the QHE occurs in a two-dimensional\u0000(2D) accumulation layer near the gate, while the bulk carriers play the role of\u0000an electron reservoir. Due to the exchange of carriers between the reservoir\u0000and the 2D layer, an anomalous scaling of the QHE is observed not with respect\u0000to the CNP, but with respect to the first electron plateau.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pranti Saha, In Jun Park, Protik Das, Fariborz Kargar
We have investigated the structural, mechanical, electronic and optical properties of Rb-based cubic perovskite RbBaX$_3$ (X = F, Cl, Br, I) under hydrostatic pressure, using first-principle density functional theory (DFT). All RbBaX$_3$ perovskites exhibit thermodynamic and mechanical stability at ambient pressure. RbBaF$_3$ remains structurally stable across all examined pressures, while RbBaCl$_3$, RbBaBr$_3$, and RbBaI$_3$ maintain mechanical stability up to 60, 60, and 40 GPa, respectively. These materials are ductile even at elevated pressure. RbBaF$_3$ has a direct bandgap of 4.80 eV while other compositions exhibit indirect band gaps of 4.37, 3.73, and 3.24 eV with halide atoms of Cl, Br, and I, respectively. Under elevated hydrostatic pressure, only RbBaCl$_3$ and RbBaI$_3$ exhibit an indirect-to direct band transition while others preserve their nature of band gap. Our results show that spin-orbit coupling significantly affects only the valance bands of larger-sized halides (Cl, Br, I). With hybrid functional (HSE) correction, the band gaps of these four materials increase to 6.7, 5.6, 4.8 and 4.4 eV, respectively, but the nature of direct/indirect band transition remains unchanged. Orbital-decomposed partial density of states calculation reveals that the halogen p-orbitals dominate the valence band near the Fermi level, while Rb 5s-orbital affects the conduction band minima the most. Investigation of the optical properties reveals wide-band absorption, low electron loss, moderate reflectivity and lower refractive index in the UV to deep-UV range. The strength and range of absorption increases significantly with hydrostatic pressure, suggesting that RbBaX$_3$ perovskites are promising candidates for tunable UV-absorbing optoelectronic devices.
{"title":"First-principles study of structural, electronic and optical properties of non-toxic RbBaX$_3$ (X = F, Cl, Br, I) perovskites under hydrostatic pressure","authors":"Pranti Saha, In Jun Park, Protik Das, Fariborz Kargar","doi":"arxiv-2409.09524","DOIUrl":"https://doi.org/arxiv-2409.09524","url":null,"abstract":"We have investigated the structural, mechanical, electronic and optical\u0000properties of Rb-based cubic perovskite RbBaX$_3$ (X = F, Cl, Br, I) under\u0000hydrostatic pressure, using first-principle density functional theory (DFT).\u0000All RbBaX$_3$ perovskites exhibit thermodynamic and mechanical stability at\u0000ambient pressure. RbBaF$_3$ remains structurally stable across all examined\u0000pressures, while RbBaCl$_3$, RbBaBr$_3$, and RbBaI$_3$ maintain mechanical\u0000stability up to 60, 60, and 40 GPa, respectively. These materials are ductile\u0000even at elevated pressure. RbBaF$_3$ has a direct bandgap of 4.80 eV while\u0000other compositions exhibit indirect band gaps of 4.37, 3.73, and 3.24 eV with\u0000halide atoms of Cl, Br, and I, respectively. Under elevated hydrostatic\u0000pressure, only RbBaCl$_3$ and RbBaI$_3$ exhibit an indirect-to direct band\u0000transition while others preserve their nature of band gap. Our results show\u0000that spin-orbit coupling significantly affects only the valance bands of\u0000larger-sized halides (Cl, Br, I). With hybrid functional (HSE) correction, the\u0000band gaps of these four materials increase to 6.7, 5.6, 4.8 and 4.4 eV,\u0000respectively, but the nature of direct/indirect band transition remains\u0000unchanged. Orbital-decomposed partial density of states calculation reveals\u0000that the halogen p-orbitals dominate the valence band near the Fermi level,\u0000while Rb 5s-orbital affects the conduction band minima the most. Investigation\u0000of the optical properties reveals wide-band absorption, low electron loss,\u0000moderate reflectivity and lower refractive index in the UV to deep-UV range.\u0000The strength and range of absorption increases significantly with hydrostatic\u0000pressure, suggesting that RbBaX$_3$ perovskites are promising candidates for\u0000tunable UV-absorbing optoelectronic devices.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vladislav D. Kurilovich, William S. Cole, Roman M. Lutchyn, Leonid I. Glazman
We develop a theory of the nonlocal conductance $G_{RL}(V)$ for a disordered Majorana wire tuned near the topological transition critical point. We show that the differential conductance is an odd function of bias, $G_{RL}(V) = -G_{RL}(-V)$. We factorize the conductance into terms describing the contacts between the wire and the normal leads, and the term describing quasiparticle propagation along the wire. Topological transition affects only the latter term. At the critical point, the quasiparticle localization length has a logarithmic singularity at the Fermi level, $l(E) propto ln(1 / E)$. This singularity directly manifests in the conductance magnitude, as $ln |G_{RL}(V) / G_Q| sim L / l(eV)$ for the wire of length $L gg l(eV)$. Tuning the wire away from the immediate vicinity of the critical point changes the monotonicity of $l(E)$. This change in monotonicty allows us to define the width of the critical region around the transition point.
{"title":"Nonlocal conductance of a Majorana wire near the topological transition","authors":"Vladislav D. Kurilovich, William S. Cole, Roman M. Lutchyn, Leonid I. Glazman","doi":"arxiv-2409.09325","DOIUrl":"https://doi.org/arxiv-2409.09325","url":null,"abstract":"We develop a theory of the nonlocal conductance $G_{RL}(V)$ for a disordered\u0000Majorana wire tuned near the topological transition critical point. We show\u0000that the differential conductance is an odd function of bias, $G_{RL}(V) =\u0000-G_{RL}(-V)$. We factorize the conductance into terms describing the contacts\u0000between the wire and the normal leads, and the term describing quasiparticle\u0000propagation along the wire. Topological transition affects only the latter\u0000term. At the critical point, the quasiparticle localization length has a\u0000logarithmic singularity at the Fermi level, $l(E) propto ln(1 / E)$. This\u0000singularity directly manifests in the conductance magnitude, as $ln |G_{RL}(V)\u0000/ G_Q| sim L / l(eV)$ for the wire of length $L gg l(eV)$. Tuning the wire\u0000away from the immediate vicinity of the critical point changes the monotonicity\u0000of $l(E)$. This change in monotonicty allows us to define the width of the\u0000critical region around the transition point.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"192 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gillian Shen, Yadong Zhang, Julisa Juarez, Hannah Contreras, Collin Sindt, Yiman Xu, Jessica Kline, Stephen Barlow, Elsa Reichmanis, Seth R. Marder, David S. Ginger
We demonstrate the use of [2-($textit{9H}$-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and [2-(3,6-di-$textit{tert}$-butyl-$textit{9H}$-carbazol-9-yl)ethyl]phosphonic acid (t-Bu-2PACz) as anode modification layers in metal-halide perovskite quantum dot light-emitting diodes (QLEDs). Compared to conventional QLED structures with PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate)/PVK (poly(9-vinylcarbazole)) hole-transport layers, QLEDs made with phosphonic acid (PA)-modified indium tin oxide (ITO) anodes show an over 7-fold increase in brightness, achieving a brightness of 373,000 cd m$^{-2}$, one of the highest brightnesses reported to date for colloidal perovskite QLEDs. Importantly, the onset of efficiency roll-off, or efficiency droop, occurs at ~1000-fold higher current density for QLEDs made with PA-modified anodes compared to control QLEDs made with conventional PEDOT:PSS/PVK hole transport layers, allowing the devices to sustain significantly higher levels of external quantum efficiency at a brightness of >10$^{5}$ cd m$^{-2}$. Steady-state and time-resolved photoluminescence measurements indicate these improvements are due to a combination of multiple factors, including reducing quenching of photoluminescence at the PEDOT:PSS interface and reducing photoluminescence efficiency loss at high levels of current density.
我们展示了[2-($textit{9H}$-carbazol-9-yl)乙基]膦酸（2PACz）和[2-(3,6-di-$textit{tert}$-butyl-$textit{9H}$-carbazol-9-yl)乙基]膦酸（t-Bu-2PACz）作为金属卤化物过共晶量子点发光二极管（QLEDs）阳极修饰层的用途。与传统的 QLED 结构相比，PEDOT：PSS（聚(3,4-乙烯二氧噻吩)聚苯乙烯磺酸盐）/PVK（聚(9-乙烯基咔唑)）空穴传输层相比，使用膦酸（PA）修饰的氧化铟锡（ITO）阳极制成的 QLED 的亮度提高了 7 倍多，达到了 373,000 cd m$^{-2}$，是迄今为止报道的胶体包晶体 QLED 的最高亮度之一。重要的是，与使用传统 PEDOT:PSS/PVK 孔传输层制造的 QLED 相比，使用 PA 修饰阳极制造的 QLED 的电流密度要高出约 1000 倍，因此在亮度大于 10$^{5}$ cd m$^{-2}$时，器件能够维持更高水平的外部量子效率。稳态和时间分辨光致发光测量结果表明，这些改进是多种因素共同作用的结果，包括减少了 PEDOT:PSS 接口处的光致发光淬灭，以及降低了高电流密度下的光致发光效率损失。
{"title":"Increased Brightness and Reduced Efficiency Droop in Perovskite Quantum Dot Light-Emitting Diodes using Carbazole-Based Phosphonic Acid Interface Modifiers","authors":"Gillian Shen, Yadong Zhang, Julisa Juarez, Hannah Contreras, Collin Sindt, Yiman Xu, Jessica Kline, Stephen Barlow, Elsa Reichmanis, Seth R. Marder, David S. Ginger","doi":"arxiv-2409.09556","DOIUrl":"https://doi.org/arxiv-2409.09556","url":null,"abstract":"We demonstrate the use of [2-($textit{9H}$-carbazol-9-yl)ethyl]phosphonic\u0000acid (2PACz) and\u0000[2-(3,6-di-$textit{tert}$-butyl-$textit{9H}$-carbazol-9-yl)ethyl]phosphonic\u0000acid (t-Bu-2PACz) as anode modification layers in metal-halide perovskite\u0000quantum dot light-emitting diodes (QLEDs). Compared to conventional QLED\u0000structures with PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene\u0000sulfonate)/PVK (poly(9-vinylcarbazole)) hole-transport layers, QLEDs made with\u0000phosphonic acid (PA)-modified indium tin oxide (ITO) anodes show an over 7-fold\u0000increase in brightness, achieving a brightness of 373,000 cd m$^{-2}$, one of\u0000the highest brightnesses reported to date for colloidal perovskite QLEDs.\u0000Importantly, the onset of efficiency roll-off, or efficiency droop, occurs at\u0000~1000-fold higher current density for QLEDs made with PA-modified anodes\u0000compared to control QLEDs made with conventional PEDOT:PSS/PVK hole transport\u0000layers, allowing the devices to sustain significantly higher levels of external\u0000quantum efficiency at a brightness of >10$^{5}$ cd m$^{-2}$. Steady-state and\u0000time-resolved photoluminescence measurements indicate these improvements are\u0000due to a combination of multiple factors, including reducing quenching of\u0000photoluminescence at the PEDOT:PSS interface and reducing photoluminescence\u0000efficiency loss at high levels of current density.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study the spatial profile of phonon angular momentum in a junction between a chiral crystal and a non-chiral (achiral) crystal with a smooth, flat contact at low temperatures. In this junction, the angular momentum is generated by an imbalance in non-equilibrium distributions between transverse acoustic modes. We incorporate the Fresnel coefficients for elastic waves to establish a boundary condition for the phonon distributions, for which we also provide a proof. We demonstrate that the spin angular momentum of phonon induced by a thermal gradient in the chiral crystal diffuses into the adjacent achiral crystal. This diffusion is accompanied by a finite orbital angular momentum stemming from acoustic analog of the Imbert--Fedorov shift in reflected/transmitted wave packets. Concerning angular momentum fluxes that are polarized normal to the interface, the sum of the spin and orbital components is continuous at the interface. This continuity confirms the conservation law of total phonon angular momentum.
{"title":"Theory of phonon angular momentum transport across smooth interfaces between crystals","authors":"Yuta Suzuki, Shuntaro Sumita, Yusuke Kato","doi":"arxiv-2409.08874","DOIUrl":"https://doi.org/arxiv-2409.08874","url":null,"abstract":"We study the spatial profile of phonon angular momentum in a junction between\u0000a chiral crystal and a non-chiral (achiral) crystal with a smooth, flat contact\u0000at low temperatures. In this junction, the angular momentum is generated by an\u0000imbalance in non-equilibrium distributions between transverse acoustic modes.\u0000We incorporate the Fresnel coefficients for elastic waves to establish a\u0000boundary condition for the phonon distributions, for which we also provide a\u0000proof. We demonstrate that the spin angular momentum of phonon induced by a\u0000thermal gradient in the chiral crystal diffuses into the adjacent achiral\u0000crystal. This diffusion is accompanied by a finite orbital angular momentum\u0000stemming from acoustic analog of the Imbert--Fedorov shift in\u0000reflected/transmitted wave packets. Concerning angular momentum fluxes that are\u0000polarized normal to the interface, the sum of the spin and orbital components\u0000is continuous at the interface. This continuity confirms the conservation law\u0000of total phonon angular momentum.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：