A discord is a refinement of the concept of an anomalous subsequence of a time series.Being one of the topical issues of time series mining,discords discovery is applied in a wide range of real-world areas(medicine,as...A discord is a refinement of the concept of an anomalous subsequence of a time series.Being one of the topical issues of time series mining,discords discovery is applied in a wide range of real-world areas(medicine,astronomy,economics,climate modeling,predictive maintenance,energy consumption,etc.).In this article,we propose a novel parallel algorithm for discords discovery on high-performance cluster with nodes based on many-core accelerators in the case when time series cannot fit in the main memory.We assumed that the time series is partitioned across the cluster nodes and achieved parallelization among the cluster nodes as well as within a single node.Within a cluster node,the algorithm employs a set of matrix data structures to store and index the subsequences of a time series,and to provide an efficient vectorization of computations on the accelerator.At each node,the algorithm processes its own partition and performs in two phases,namely candidate selection and discord refinement,with each phase requiring one linear scan through the partition.Then the local discords found are combined into the global candidate set and transmitted to each cluster node.Next,a node performs refinement of the global candidate set over its own partition resulting in the local true discord set.Finally,the global true discords set is constructed as intersection of the local true discord sets.The experimental evaluation on the real computer cluster with real and synthetic time series shows a high scalability of the proposed algorithm.展开更多
The recent study published by Lee et al examined the discrepancies between endoscopic and histologic evaluations of mucosal inflammation in active ileal Crohn’s disease(CD).While this research contributes to our unde...The recent study published by Lee et al examined the discrepancies between endoscopic and histologic evaluations of mucosal inflammation in active ileal Crohn’s disease(CD).While this research contributes to our understanding of the limitations of current biopsy protocols,it raises several concerns about the generalizability of its findings,sample size,and methodology.One major limitation was the exclusion of patients with ileal strictures,ileostomies,or J-pouches,which reduced the applicability of the results to the wider CD population.Furthermore,the biopsy protocol's focus on single biopsies from specific locations may inadequately capture the patchy inflammation characteristic of CD.The study also uses histologic indices primarily developed for ulcerative colitis,which may not be suitable for assessing CD.It is recommended that multi-center studies be conducted and histologic indices specific to CD be developed to improve the relevance of future research.Additionally,researchers should consider the influence of treatment regimens on the findings.Addressing these limitations would enhance the clinical significance of the study and inform better diagnostic and therapeutic approaches for CD.展开更多
Using quantum discord(QD)and geometric quantum discord(GQD),quantum correlation dynamics is investigated for two coupled qubits within a multiqubit interacting system in the zero-temperature bosonic reservoir,under bo...Using quantum discord(QD)and geometric quantum discord(GQD),quantum correlation dynamics is investigated for two coupled qubits within a multiqubit interacting system in the zero-temperature bosonic reservoir,under both weak and strong qubit-reservoir coupling regimes.The multiqubit system is connected with either a common bosonic reservoir(CBR)or multiple independent bosonic reservoirs(IBRs).In the CBR case,our findings indicate that both QD and GQD can be strengthened by increasing the number of qubits in the multiqubit system.Furthermore,we study the steady state QD and GQD in the strong coupling regime,and find that the stable value in the long-time limit is determined exclusively by the number of qubits.The evolution period of QD and GQD gets longer as the dipole–dipole interaction(DDI)strength increases,which helps prolong the correlation time and thus preserves the quantum correlation under the weak coupling regime.Further analysis reveals notable differences between the CBR and IBRs scenarios.In the IBRs case,the decay of QD and GQD becomes slower compared to the CBR case,with both measures tending to zero at a reduced rate.Moreover,GQD consistently exhibits lower values than QD in both scenarios.These findings provide valuable insights into the selection of appropriate correlation measurement techniques for quantifying quantum correlations.展开更多
BACKGROUND Discordance between endoscopic and histologic assessments in Crohn’s disease(CD)have been observed,however the prevalence and cause are unclear.AIM To assess if a protocolized approach to biopsy collection...BACKGROUND Discordance between endoscopic and histologic assessments in Crohn’s disease(CD)have been observed,however the prevalence and cause are unclear.AIM To assess if a protocolized approach to biopsy collection facilitates understanding of this discordance in patients with ileal CD.METHODS Patients with known ileal CD underwent colonoscopy with endoscopic disease activity assessment.Three protocolized biopsies were taken respectively from an ulcer edge,7-mm,and 14-mm away from the ulcer edge in patients with discrete ileal ulcer(s).In patients with no ulcers as controls,the same 3-site biopsy protocol was applied in a randomly selected area of endoscopically-unremarkable terminal ileal mucosa.A blinded pathologist assessed mucosal inflammation in each biopsy using 3 validated histologic indices.RESULTS Twenty-four participants had visible ulcer(s)on endoscopy and 12 served as no-ulcer controls.Of biopsies taken from an ulcer edge,only 67%showed histologic evidence of active(neutrophilic)inflammation,and 33%showed histologic features of ulcer or erosion;all were from either large(n=4)or very large(n=4)ulcers.In the no-ulcer controls,no biopsies showed histologic features of ulcer or erosion,but 8%showed active inflammation.CONCLUSION A striking discordance exists between endoscopic and histologic assessments for mucosal inflammation in patients with active ileal CD,even in biopsies targeted at an ulcer edge,while a higher concordance is seen in patients with no endoscopic disease activity.It remains unclear how to incorporate histologic disease activity into the treatment paradigm.Further research is needed to optimize biopsy protocols and histologic assessments for CD.展开更多
Background:This study assessed the frequency of changes in some key receptor status of tumors after neoadjuvant chemotherapy(NAC)in patients with invasive breast cancer and the prognostic impact of these changes.Metho...Background:This study assessed the frequency of changes in some key receptor status of tumors after neoadjuvant chemotherapy(NAC)in patients with invasive breast cancer and the prognostic impact of these changes.Methods:This study included 300 patients diagnosed with invasive breast cancer who were treated with both NAC and surgery between 2012 and 2021.The hormone receptor(HR)and human epidermal growth factor receptor 2(HER2)levels were measured before and after NAC.The prognostic impact of receptor conversion was also evaluated in patients receiving NAC,by using the Kaplan-Meier method and Cox proportional hazards models as statistical methods.Results:The conversion rate of estrogen receptor–positive(ER^(+))to ER-negative(ER^(-))was similar to that of ER^(-)to ER^(+)(9.2%and10.9%,respectively).The proportion of HR^(-)to HR^(+)was remarkably higher than that of HR^(+)to HR^(-)(14.8%vs 9.2%,respectively).The change from HER2^(+)to HER2^(-)was significantly more frequently than that from HER2^(-)to HER2^(+)(20.3%vs 6%,respectively).Patients with ER and HR status changes from(-)to(+)after NAC had significantly worse recurrence-free survival(RFS)and overall survival(OS)than those in the other 3 groups(ER^(-)to ER^(+):RFS:p=0.002,OS:p<0.001;HR^(-)to HR^(+):RFS:p=0.003,OS:p<0.001).The 4 HER2 conversion subgroups were not significantly associated with RFS or OS.Conclusions:This study demonstrated a discordance in HR status after NAC and identified predictors of conversion.Patients whose HR status switched to positive after NAC had the worst 3-year RFS and OS rates.展开更多
Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized co...Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics.This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections.A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others.Four configurations with different bed discordance ratios were investigated.The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces.The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step.Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio.It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently.展开更多
Most studies exploring abilities of hosts to detect brood parasitism are based on detecting colour and/or pattern differences among parasitic and host eggs or nestlings,while only few were focused on size differences....Most studies exploring abilities of hosts to detect brood parasitism are based on detecting colour and/or pattern differences among parasitic and host eggs or nestlings,while only few were focused on size differences.True recognition and recognition by discordancy are used to explain cognitive mechanisms of host egg recognition;however,only a few studies have found that hosts use recognition by discordancy.This study investigated:1)whether egg and nestling recognitions in the Crested Myna(Acridotheres cristatellus) are based on size cues;2)whether the egg cognitive mechanism is recognition by discordancy based on size cues;and 3) whether the longer the experiment time,the higher the egg recognition rate.Our results showed that the Crested Myna uses egg or nestling size as a recognition cue while the egg and nestling colour and patterning are not associated with egg or nestling rejection,thus the cognitive mechanism of egg recognition in the Crested Myna is recognition by discordancy based on egg size cues.Furthermore,there is a rejection delay in time of egg rejection behaviour of the Crested Myna.Therefore,we suggest that the periodicity of egg rejection experiments could be appropriately extended,especially for species with relatively low egg recognition ability.展开更多
Background:Nest parasitism by cuckoos(Cuculus spp.)results in enormous reproductive failure and forces hosts to evolve antiparasitic strategies,i.e.,recognition of own eggs and rejection of cuckoo eggs.There are often...Background:Nest parasitism by cuckoos(Cuculus spp.)results in enormous reproductive failure and forces hosts to evolve antiparasitic strategies,i.e.,recognition of own eggs and rejection of cuckoo eggs.There are often sexual conflicts between male and female individuals in the expression of antiparasitic behavior due to the differences in reproductive inputs and division of labor.Methods:By adding a foreign egg made of blue soft clay to the host nest during early incubation period in the field,and by removing several host eggs and adding experimental eggs to control the proportion of two egg types in the nest,we examined egg rejection ability,egg recognition mechanism and sexual difference in egg rejection of the Oriental Reed Warbler(Acrocephalus orientalis),one of the major hosts of Common Cuckoos(Cuculus canorus).Results:Our results indicated that Oriental Reed Warblers can recognize and reject nearly 100%(73/75)of the nonmimetic eggs made of blue soft clay,and they could reject foreign eggs with 100%accuracy,regardless of the ratio of experimental eggs and its own eggs in the nest.Furthermore,all cases of egg rejections recorded by videos were only carried out by females.Conclusions:Oriental Reed Warblers have a high egg recognition ability and show a true recognition mechanism.Only female warblers perform egg rejection,suggesting that the sex for host egg incubation seems to play an important role in the evolution of egg recognition mechanisms.展开更多
Quantum correlation shows a fascinating nature of quantum mechanics and plays an important role in some physics topics,especially in the field of quantum information.Quantum correlations of the composite system can be...Quantum correlation shows a fascinating nature of quantum mechanics and plays an important role in some physics topics,especially in the field of quantum information.Quantum correlations of the composite system can be quantified by resorting to geometric or entropy methods,and all these quantification methods exhibit the peculiar freezing phenomenon.The challenge is to find the characteristics of the quantum states that generate the freezing phenomenon,rather than only study the conditions which generate this phenomenon under a certain quantum system.In essence,this is a classification problem.Machine learning has become an effective method for researchers to study classification and feature generation.In this work,we prove that the machine learning can solve the problem of X form quantum states,which is a problem of physical significance.Subsequently,we apply the density-based spatial clustering of applications with noise(DBSCAN)algorithm and the decision tree to divide quantum states into two different groups.Our goal is to classify the quantum correlations of quantum states into two classes:one is the quantum correlation with freezing phenomenon for both Rènyi discord(α=2)and the geometric discord(Bures distance),the other is the quantum correlation of non-freezing phenomenon.The results demonstrate that the machine learning method has reasonable performance in quantum correlation research.展开更多
The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable d...The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as Dx and Dx when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter Dx is more efficient than parameter Dz in most regions for controlling the QD.展开更多
We investigate a two=level atom interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence and find that a stationary quantum discord can arise in the interaction of t...We investigate a two=level atom interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence and find that a stationary quantum discord can arise in the interaction of the atom and cavity field as the time turns to infinity. We also find that the stationary quantum discord can be increased by applying a classical driving field. Furthermore, we explore the quantum discord dynamics of two identical non=interacting two-level atoms independently interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence. Results show that the quantum discord between two atoms is more robust than entanglement under phase decoherence and the classical driving field can help to improve the amount of quantum discord of the two atoms.展开更多
基金the Russian Foundation for Basic Research(Grant No.20-07-00140)the Ministry of Science and Higher Education of the Russian Federation(Government Order FENU-2020-0022).
文摘A discord is a refinement of the concept of an anomalous subsequence of a time series.Being one of the topical issues of time series mining,discords discovery is applied in a wide range of real-world areas(medicine,astronomy,economics,climate modeling,predictive maintenance,energy consumption,etc.).In this article,we propose a novel parallel algorithm for discords discovery on high-performance cluster with nodes based on many-core accelerators in the case when time series cannot fit in the main memory.We assumed that the time series is partitioned across the cluster nodes and achieved parallelization among the cluster nodes as well as within a single node.Within a cluster node,the algorithm employs a set of matrix data structures to store and index the subsequences of a time series,and to provide an efficient vectorization of computations on the accelerator.At each node,the algorithm processes its own partition and performs in two phases,namely candidate selection and discord refinement,with each phase requiring one linear scan through the partition.Then the local discords found are combined into the global candidate set and transmitted to each cluster node.Next,a node performs refinement of the global candidate set over its own partition resulting in the local true discord set.Finally,the global true discords set is constructed as intersection of the local true discord sets.The experimental evaluation on the real computer cluster with real and synthetic time series shows a high scalability of the proposed algorithm.
文摘The recent study published by Lee et al examined the discrepancies between endoscopic and histologic evaluations of mucosal inflammation in active ileal Crohn’s disease(CD).While this research contributes to our understanding of the limitations of current biopsy protocols,it raises several concerns about the generalizability of its findings,sample size,and methodology.One major limitation was the exclusion of patients with ileal strictures,ileostomies,or J-pouches,which reduced the applicability of the results to the wider CD population.Furthermore,the biopsy protocol's focus on single biopsies from specific locations may inadequately capture the patchy inflammation characteristic of CD.The study also uses histologic indices primarily developed for ulcerative colitis,which may not be suitable for assessing CD.It is recommended that multi-center studies be conducted and histologic indices specific to CD be developed to improve the relevance of future research.Additionally,researchers should consider the influence of treatment regimens on the findings.Addressing these limitations would enhance the clinical significance of the study and inform better diagnostic and therapeutic approaches for CD.
基金supported by the National Natural Science Foundation of China(Grant Nos.11564013 and 11964010)the Natural Science Foundation of Hunan Province(Grant No.2020JJ4495)the Scientific Research Fund of Hunan Provincial Education Department,China(Grant Nos.22A0377 and 21A0333).
文摘Using quantum discord(QD)and geometric quantum discord(GQD),quantum correlation dynamics is investigated for two coupled qubits within a multiqubit interacting system in the zero-temperature bosonic reservoir,under both weak and strong qubit-reservoir coupling regimes.The multiqubit system is connected with either a common bosonic reservoir(CBR)or multiple independent bosonic reservoirs(IBRs).In the CBR case,our findings indicate that both QD and GQD can be strengthened by increasing the number of qubits in the multiqubit system.Furthermore,we study the steady state QD and GQD in the strong coupling regime,and find that the stable value in the long-time limit is determined exclusively by the number of qubits.The evolution period of QD and GQD gets longer as the dipole–dipole interaction(DDI)strength increases,which helps prolong the correlation time and thus preserves the quantum correlation under the weak coupling regime.Further analysis reveals notable differences between the CBR and IBRs scenarios.In the IBRs case,the decay of QD and GQD becomes slower compared to the CBR case,with both measures tending to zero at a reduced rate.Moreover,GQD consistently exhibits lower values than QD in both scenarios.These findings provide valuable insights into the selection of appropriate correlation measurement techniques for quantifying quantum correlations.
文摘BACKGROUND Discordance between endoscopic and histologic assessments in Crohn’s disease(CD)have been observed,however the prevalence and cause are unclear.AIM To assess if a protocolized approach to biopsy collection facilitates understanding of this discordance in patients with ileal CD.METHODS Patients with known ileal CD underwent colonoscopy with endoscopic disease activity assessment.Three protocolized biopsies were taken respectively from an ulcer edge,7-mm,and 14-mm away from the ulcer edge in patients with discrete ileal ulcer(s).In patients with no ulcers as controls,the same 3-site biopsy protocol was applied in a randomly selected area of endoscopically-unremarkable terminal ileal mucosa.A blinded pathologist assessed mucosal inflammation in each biopsy using 3 validated histologic indices.RESULTS Twenty-four participants had visible ulcer(s)on endoscopy and 12 served as no-ulcer controls.Of biopsies taken from an ulcer edge,only 67%showed histologic evidence of active(neutrophilic)inflammation,and 33%showed histologic features of ulcer or erosion;all were from either large(n=4)or very large(n=4)ulcers.In the no-ulcer controls,no biopsies showed histologic features of ulcer or erosion,but 8%showed active inflammation.CONCLUSION A striking discordance exists between endoscopic and histologic assessments for mucosal inflammation in patients with active ileal CD,even in biopsies targeted at an ulcer edge,while a higher concordance is seen in patients with no endoscopic disease activity.It remains unclear how to incorporate histologic disease activity into the treatment paradigm.Further research is needed to optimize biopsy protocols and histologic assessments for CD.
基金supported by grants from the Basic Research Project of Shanxi Science and Technology Department(no.202303021221190)the Shanxi General Surgery“136”Healthcare Engineering Project(no.2024XYZ03)。
文摘Background:This study assessed the frequency of changes in some key receptor status of tumors after neoadjuvant chemotherapy(NAC)in patients with invasive breast cancer and the prognostic impact of these changes.Methods:This study included 300 patients diagnosed with invasive breast cancer who were treated with both NAC and surgery between 2012 and 2021.The hormone receptor(HR)and human epidermal growth factor receptor 2(HER2)levels were measured before and after NAC.The prognostic impact of receptor conversion was also evaluated in patients receiving NAC,by using the Kaplan-Meier method and Cox proportional hazards models as statistical methods.Results:The conversion rate of estrogen receptor–positive(ER^(+))to ER-negative(ER^(-))was similar to that of ER^(-)to ER^(+)(9.2%and10.9%,respectively).The proportion of HR^(-)to HR^(+)was remarkably higher than that of HR^(+)to HR^(-)(14.8%vs 9.2%,respectively).The change from HER2^(+)to HER2^(-)was significantly more frequently than that from HER2^(-)to HER2^(+)(20.3%vs 6%,respectively).Patients with ER and HR status changes from(-)to(+)after NAC had significantly worse recurrence-free survival(RFS)and overall survival(OS)than those in the other 3 groups(ER^(-)to ER^(+):RFS:p=0.002,OS:p<0.001;HR^(-)to HR^(+):RFS:p=0.003,OS:p<0.001).The 4 HER2 conversion subgroups were not significantly associated with RFS or OS.Conclusions:This study demonstrated a discordance in HR status after NAC and identified predictors of conversion.Patients whose HR status switched to positive after NAC had the worst 3-year RFS and OS rates.
文摘Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics.This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections.A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others.Four configurations with different bed discordance ratios were investigated.The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces.The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step.Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio.It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently.
基金supported by the National Natural Science Foundation of China (No.31970427 and 32270526 to WL)supported by the specific research fund of The Innovation Platform for Academicians of Hainan Province
文摘Most studies exploring abilities of hosts to detect brood parasitism are based on detecting colour and/or pattern differences among parasitic and host eggs or nestlings,while only few were focused on size differences.True recognition and recognition by discordancy are used to explain cognitive mechanisms of host egg recognition;however,only a few studies have found that hosts use recognition by discordancy.This study investigated:1)whether egg and nestling recognitions in the Crested Myna(Acridotheres cristatellus) are based on size cues;2)whether the egg cognitive mechanism is recognition by discordancy based on size cues;and 3) whether the longer the experiment time,the higher the egg recognition rate.Our results showed that the Crested Myna uses egg or nestling size as a recognition cue while the egg and nestling colour and patterning are not associated with egg or nestling rejection,thus the cognitive mechanism of egg recognition in the Crested Myna is recognition by discordancy based on egg size cues.Furthermore,there is a rejection delay in time of egg rejection behaviour of the Crested Myna.Therefore,we suggest that the periodicity of egg rejection experiments could be appropriately extended,especially for species with relatively low egg recognition ability.
基金supported by the National Natural Science Foundation of China(No.31970427 to WL and 32101242 to LM)by the Open Foundation of Hebei Key Laboratory of Wetland Ecology and Conservation(hklk201903 to LM)the Natural Science Foundation of Hebei Province of China(C2020101002 to LM)。
文摘Background:Nest parasitism by cuckoos(Cuculus spp.)results in enormous reproductive failure and forces hosts to evolve antiparasitic strategies,i.e.,recognition of own eggs and rejection of cuckoo eggs.There are often sexual conflicts between male and female individuals in the expression of antiparasitic behavior due to the differences in reproductive inputs and division of labor.Methods:By adding a foreign egg made of blue soft clay to the host nest during early incubation period in the field,and by removing several host eggs and adding experimental eggs to control the proportion of two egg types in the nest,we examined egg rejection ability,egg recognition mechanism and sexual difference in egg rejection of the Oriental Reed Warbler(Acrocephalus orientalis),one of the major hosts of Common Cuckoos(Cuculus canorus).Results:Our results indicated that Oriental Reed Warblers can recognize and reject nearly 100%(73/75)of the nonmimetic eggs made of blue soft clay,and they could reject foreign eggs with 100%accuracy,regardless of the ratio of experimental eggs and its own eggs in the nest.Furthermore,all cases of egg rejections recorded by videos were only carried out by females.Conclusions:Oriental Reed Warblers have a high egg recognition ability and show a true recognition mechanism.Only female warblers perform egg rejection,suggesting that the sex for host egg incubation seems to play an important role in the evolution of egg recognition mechanisms.
基金supported by the National Natural Science Foundation of China(61502082)National Key R&D Program of China,Grant No.(2018YFA0306703).
文摘Quantum correlation shows a fascinating nature of quantum mechanics and plays an important role in some physics topics,especially in the field of quantum information.Quantum correlations of the composite system can be quantified by resorting to geometric or entropy methods,and all these quantification methods exhibit the peculiar freezing phenomenon.The challenge is to find the characteristics of the quantum states that generate the freezing phenomenon,rather than only study the conditions which generate this phenomenon under a certain quantum system.In essence,this is a classification problem.Machine learning has become an effective method for researchers to study classification and feature generation.In this work,we prove that the machine learning can solve the problem of X form quantum states,which is a problem of physical significance.Subsequently,we apply the density-based spatial clustering of applications with noise(DBSCAN)algorithm and the decision tree to divide quantum states into two different groups.Our goal is to classify the quantum correlations of quantum states into two classes:one is the quantum correlation with freezing phenomenon for both Rènyi discord(α=2)and the geometric discord(Bures distance),the other is the quantum correlation of non-freezing phenomenon.The results demonstrate that the machine learning method has reasonable performance in quantum correlation research.
基金Supported by the National Natural Science Foundation of China under Grant Nos.90503009,10775116973 Program under Grant No.2005CB724508
文摘The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as Dx and Dx when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter Dx is more efficient than parameter Dz in most regions for controlling the QD.
基金Project supported by National Natural Science Foundation of China (Grant No. 10774143)
文摘We investigate a two=level atom interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence and find that a stationary quantum discord can arise in the interaction of the atom and cavity field as the time turns to infinity. We also find that the stationary quantum discord can be increased by applying a classical driving field. Furthermore, we explore the quantum discord dynamics of two identical non=interacting two-level atoms independently interacting with a quantized cavity field and a classical driving field in the presence of phase decoherence. Results show that the quantum discord between two atoms is more robust than entanglement under phase decoherence and the classical driving field can help to improve the amount of quantum discord of the two atoms.
