The orthogonality catastrophe(OC)of quantum many-body systems is an important phenomenon in condensed matter physics.Recently,an interesting relationship between the OC and the quantum speed limit(QSL)was shown(Fogart...The orthogonality catastrophe(OC)of quantum many-body systems is an important phenomenon in condensed matter physics.Recently,an interesting relationship between the OC and the quantum speed limit(QSL)was shown(Fogarty 2020 Phys.Rev.Lett.124110601).Inspired by the remarkable feature,we provide a quantitative version of the quantum average speed as another different method to investigate the measure of how it is close to the OC dynamics.We analyze the properties of an impurity qubit embedded into an isotropic Lipkin-Meshkov-Glick spin model,and show that the OC dynamics can also be characterized by the average speed of the evolution state.Furthermore,a similar behavior of the actual speed of quantum evolution and the theoretical maximal rate is shown which can provide an alternative speed-up protocol allowing us to understand some universal properties characterized by the QSL.展开更多
The unified bound on the fundamental limit of quantum dynamics rate, as quietly recently obtainedby Levitin and Toffoli [Phys.Rev.Lett.103 (2009) 160502], is improved and refined.The improvement may bearbitrarily larg...The unified bound on the fundamental limit of quantum dynamics rate, as quietly recently obtainedby Levitin and Toffoli [Phys.Rev.Lett.103 (2009) 160502], is improved and refined.The improvement may bearbitrarily large in certain cases.In particular, this puts a limit on the operation rate of quantum gates allowed byquantum mechanics.展开更多
The formation of sintering necks between two metal fibers was investigated using the oval-oval model with respect to the fiber angle range of 0°-90°. Surface diffusion was assumed to be the predominant mecha...The formation of sintering necks between two metal fibers was investigated using the oval-oval model with respect to the fiber angle range of 0°-90°. Surface diffusion was assumed to be the predominant mechanism in every section of the junction of two metal fibers in this model, which was addressed numerically using the level- set method. The growth rates of the sintering necks in the direction of the bisector of obtuse angle, the bisector of acute angle and the fiber axis were discussed in detail. It is found that the growth rate of the sintering necks decreases with fiber angle increasing in the direction of the fiber axis and the bisector of acute angle. However, an opposite variation in growth rate of sintering necks can be found in the direction of the bisector of obtuse angle. The numerical simulation results show that the growth rate of the sintering necks is significantly affected by the initial local geomet- rical structure which is determined by the fiber angle.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.11875086 and11775019。
文摘The orthogonality catastrophe(OC)of quantum many-body systems is an important phenomenon in condensed matter physics.Recently,an interesting relationship between the OC and the quantum speed limit(QSL)was shown(Fogarty 2020 Phys.Rev.Lett.124110601).Inspired by the remarkable feature,we provide a quantitative version of the quantum average speed as another different method to investigate the measure of how it is close to the OC dynamics.We analyze the properties of an impurity qubit embedded into an isotropic Lipkin-Meshkov-Glick spin model,and show that the OC dynamics can also be characterized by the average speed of the evolution state.Furthermore,a similar behavior of the actual speed of quantum evolution and the theoretical maximal rate is shown which can provide an alternative speed-up protocol allowing us to understand some universal properties characterized by the QSL.
基金Supported by the National Natural Science Foundation of China under Grant No.10771208the Science Fund for Creative Research Groups under Grant No.10721101the Key Lab of Random Complex Structures and Data Science,CAS,under Grant No.2008DP173182
文摘The unified bound on the fundamental limit of quantum dynamics rate, as quietly recently obtainedby Levitin and Toffoli [Phys.Rev.Lett.103 (2009) 160502], is improved and refined.The improvement may bearbitrarily large in certain cases.In particular, this puts a limit on the operation rate of quantum gates allowed byquantum mechanics.
基金financially supported by the National Natural Science Foundation of China (Nos. 51174236 and 51134003)the National Basic Research Program of China (No. 2011CB606306)the Opening Project of State Key Laboratory of Porous Metal Materials (No. PMM-SKL-4-2012)
文摘The formation of sintering necks between two metal fibers was investigated using the oval-oval model with respect to the fiber angle range of 0°-90°. Surface diffusion was assumed to be the predominant mechanism in every section of the junction of two metal fibers in this model, which was addressed numerically using the level- set method. The growth rates of the sintering necks in the direction of the bisector of obtuse angle, the bisector of acute angle and the fiber axis were discussed in detail. It is found that the growth rate of the sintering necks decreases with fiber angle increasing in the direction of the fiber axis and the bisector of acute angle. However, an opposite variation in growth rate of sintering necks can be found in the direction of the bisector of obtuse angle. The numerical simulation results show that the growth rate of the sintering necks is significantly affected by the initial local geomet- rical structure which is determined by the fiber angle.
