Pre-and post-selected(PPS) measurement, especially the weak PPS measurement, has been proved to be a useful tool for measuring extremely tiny physical parameters. However, it is difficult to retain both the attainable...Pre-and post-selected(PPS) measurement, especially the weak PPS measurement, has been proved to be a useful tool for measuring extremely tiny physical parameters. However, it is difficult to retain both the attainable highest measurement sensitivity and precision with the increase of the parameter to be measured. Here, a modulated PPS measurement scheme based on coupling-strength-dependent modulation is presented with the highest sensitivity and precision retained for an arbitrary coupling strength. This idea is demonstrated by comparing the modulated PPS measurement scheme with the standard PPS measurement scheme in the case of unbalanced input meter. By using the Fisher information metric, we derive the optimal pre-and post-selected states, as well as the optimal coupling-strength-dependent modulation without any restriction on the coupling strength. We also give the specific strategy of performing the modulated PPS measurement scheme, which may promote practical application of this scheme in precision metrology.展开更多
In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the tw...In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the two light beams. Since both light beams are diffracted when passing through the optical systems, the spatial resolution of ghost imaging is in general lower than that of a corresponding conventional imaging system. When Gaussian-shaped light spots are used to illuminate an object, randomly scanning across the object plane, in the ghost imaging scheme, we show th√at by localizing central positions of the spots of the reference light beam, the resolution can be increased by a factor of 2^(1/2) same as that of the corresponding conventional imaging system. We also find that the resolution can be further enhanced by setting an appropriate threshold to the bucket measurement of ghost imaging.展开更多
After positive selection and lineage commitment,the TCRαβ^+CD4/CD8 SP medullary thymocytes migrate into and reside in thymic medulla,where they undergo an ordered program of late stage of T cell functional maturatio...After positive selection and lineage commitment,the TCRαβ^+CD4/CD8 SP medullary thymocytes migrate into and reside in thymic medulla,where they undergo an ordered program of late stage of T cell functional maturation and negative selection to delete self-reactive clones by apoptosis.Accomplishment of this final differentiation pathway,a physiological T cell repertoire is formed:T cells acquire immunocompetence to respond to foreign antigens and tolerance to self-antigens,ready for the emigration to homing to the T cell regions of peripheral lymphoid organs and tissues.In this review,emphases are put on introducing the approaches applied in this area and our own observations.Basically,we have analyzed the late stage of medullary thymocyte phenotypic differentiation pathways of both CD4 SP and CD8 SP medullary thymocytes and the concomitant functional maturation pathway,in particular,of CD4 SP thymocytes.It is to provide a standard to compare the functional capacity of the cells at the developmental stages induced by different conditions.The cellular and molecular basis of this differentiation process has been partially described.Cellular & Molecular Immunology.2004;1(1):3-11.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11674234 and 11605205)the Fundamental Research Funds for the Central Universities,China(Grant No.2012017yjsy143)+4 种基金the National Key Research and Development Program of China(Grant No.2017YFA0305200)the Youth Innovation Promotion Association of Chinese Academy of Sciences(CAS)(Grant No.2015317)the Natural Science Foundation of Chongqing,China(Grant Nos.cstc2015jcyjA00021 and cstc2018jcyjAX0656)the Entrepreneurship and Innovation Support Program for Chongqing Overseas Returnees,China(Grant No.cx017134)the Fund of CAS Key Laboratory of Microscale Magnetic Resonance,China,and the Fund of CAS Key Laboratory of Quantum Information,China
文摘Pre-and post-selected(PPS) measurement, especially the weak PPS measurement, has been proved to be a useful tool for measuring extremely tiny physical parameters. However, it is difficult to retain both the attainable highest measurement sensitivity and precision with the increase of the parameter to be measured. Here, a modulated PPS measurement scheme based on coupling-strength-dependent modulation is presented with the highest sensitivity and precision retained for an arbitrary coupling strength. This idea is demonstrated by comparing the modulated PPS measurement scheme with the standard PPS measurement scheme in the case of unbalanced input meter. By using the Fisher information metric, we derive the optimal pre-and post-selected states, as well as the optimal coupling-strength-dependent modulation without any restriction on the coupling strength. We also give the specific strategy of performing the modulated PPS measurement scheme, which may promote practical application of this scheme in precision metrology.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11534008,11605126,and 11804271)the Fund from the Ministry of Science and Technology of China(Grant No.2016YFA0301404)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province,China(Grant No.2017JQ1025)the Doctoral Fund of the Ministry of Education of China(Grant Nos.2016M592772 and 2018M631137)the Fundamental Research Funds for the Central Universities
文摘In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the two light beams. Since both light beams are diffracted when passing through the optical systems, the spatial resolution of ghost imaging is in general lower than that of a corresponding conventional imaging system. When Gaussian-shaped light spots are used to illuminate an object, randomly scanning across the object plane, in the ghost imaging scheme, we show th√at by localizing central positions of the spots of the reference light beam, the resolution can be increased by a factor of 2^(1/2) same as that of the corresponding conventional imaging system. We also find that the resolution can be further enhanced by setting an appropriate threshold to the bucket measurement of ghost imaging.
文摘After positive selection and lineage commitment,the TCRαβ^+CD4/CD8 SP medullary thymocytes migrate into and reside in thymic medulla,where they undergo an ordered program of late stage of T cell functional maturation and negative selection to delete self-reactive clones by apoptosis.Accomplishment of this final differentiation pathway,a physiological T cell repertoire is formed:T cells acquire immunocompetence to respond to foreign antigens and tolerance to self-antigens,ready for the emigration to homing to the T cell regions of peripheral lymphoid organs and tissues.In this review,emphases are put on introducing the approaches applied in this area and our own observations.Basically,we have analyzed the late stage of medullary thymocyte phenotypic differentiation pathways of both CD4 SP and CD8 SP medullary thymocytes and the concomitant functional maturation pathway,in particular,of CD4 SP thymocytes.It is to provide a standard to compare the functional capacity of the cells at the developmental stages induced by different conditions.The cellular and molecular basis of this differentiation process has been partially described.Cellular & Molecular Immunology.2004;1(1):3-11.
