We introduce a modified weak value that is related to the mean value of input meter variable.With the help of the modified weak value,the validity conditions for various modified versions of weak value formalism are i...We introduce a modified weak value that is related to the mean value of input meter variable.With the help of the modified weak value,the validity conditions for various modified versions of weak value formalism are investigated,in terms of the dependence of the pointer shift on the mean value of the input meter.The weak value formalism,often used to represent the pointer shift,with the modified weak value is of great use in simplifying calculations and giving guidance of practical experiments whenever the mean value of the input meter variable is nonzero.The simulation in a qubit system is presented and coincident well with our theoretical result.展开更多
Weak value amplification has shown its superiority in measurement of small physical effects. Here we introduce a signal-recycled weak-value-based velocity measurement strategy to decrease the attenuation of detected p...Weak value amplification has shown its superiority in measurement of small physical effects. Here we introduce a signal-recycled weak-value-based velocity measurement strategy to decrease the attenuation of detected photons during the post-selection. Like the power-recycled scheme, we can improve the number of detected photons and signal-to-noise ratio of velocity by forming a cavity. However, optimal improvements of number of detected photons and signal-to-noise ratio cannot be obtained simultaneously in our signal-recycled scheme owing to the walk-off effect. Furthermore, we find that the reflected light is relatively strong compared with the power-recycled scheme, which may increase the collection-detection efficiency in prospective relevant experiment.展开更多
Wavefunction is a fundamental concept of quantum theory.Recent studies have shown surprisingly that wavefunction can be directly reconstructed via the measurement of weak value.The weak value based direct wavefunction...Wavefunction is a fundamental concept of quantum theory.Recent studies have shown surprisingly that wavefunction can be directly reconstructed via the measurement of weak value.The weak value based direct wavefunction reconstruction not only gives the operational meaning of wavefunction,but also provides the possibility of realizing holographic imaging with a totally new quantum approach.Here,we review the basic background knowledge of weak value based direct wavefunction reconstruction combined with recent experimental demonstrations.The main purpose of this work focuses on the idea of holographic imaging via direct wavefunction reconstruction.Since research on this topic is still in its early stage,we hope that this work can attract interest in the field of traditional holographic imaging.In addition,the wavefunction holographic imaging may find important applications in quantum information science.展开更多
Postselected von Neumann measurement characterized by postselection and weak value has been found to possess potential applications in quantum metrology and solved plenty of fundamental problems in quantum theory. As ...Postselected von Neumann measurement characterized by postselection and weak value has been found to possess potential applications in quantum metrology and solved plenty of fundamental problems in quantum theory. As an application of this new measurement technique in quantum optics and quantum information processing, its effects on the features of single-mode radiation fields such as coherent state, squeezed vacuum state and Schrödinger cat sate are investigated by considering full-order effects of unitary evolution. The results show that the conditional probabilities of finding photons, second-order correlation functions, Qm-factors and squeezing effects of those states after the postselected measurement is significantly changed are comparable with the corresponding initial pointer states.展开更多
In this study,we give a new proposal to measure the temperature of the spin in a sample in a magnetic resonance force microscopy system by using postselected weak measurement,and investigating the Fisher information t...In this study,we give a new proposal to measure the temperature of the spin in a sample in a magnetic resonance force microscopy system by using postselected weak measurement,and investigating the Fisher information to estimate the precision of the scheme.We show that in a high temperature regime the temperature of the spin can be measured via a weak measurement technique with proper postselection and our scheme is able to increase the precision of temperature estimation.展开更多
基金National Key R&D Program of China(Grant No.2017YFA0305200)the National Natural Science Foundation of China(Grant Nos.11674234 and 11605205)+4 种基金the Natural Science Foundation of Chongqing,China(Grant Nos.cstc2015jcyjA00021 and cstc2018jcyjAX0656)Innovation Project of Sichuan University,China(Grant No.2018SCUH0021)the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2015317)the Entrepreneurship and Innovation Support Program for Chongqing Overseas Returnees,China(Grant Nos.cx2017134 and cx2018040)the Fund of CAS Key Laboratory of Microscale Magnetic Resonance,and the Fund of CAS Key Laboratory of Quantum Information,China.
文摘We introduce a modified weak value that is related to the mean value of input meter variable.With the help of the modified weak value,the validity conditions for various modified versions of weak value formalism are investigated,in terms of the dependence of the pointer shift on the mean value of the input meter.The weak value formalism,often used to represent the pointer shift,with the modified weak value is of great use in simplifying calculations and giving guidance of practical experiments whenever the mean value of the input meter variable is nonzero.The simulation in a qubit system is presented and coincident well with our theoretical result.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11674120 and 11734015)the Fundamental Research Funds for the Central Universities of the Ministry of Education of China (Grant Nos. CCNU19TS074 and CCNU18CXTD01)。
文摘Weak value amplification has shown its superiority in measurement of small physical effects. Here we introduce a signal-recycled weak-value-based velocity measurement strategy to decrease the attenuation of detected photons during the post-selection. Like the power-recycled scheme, we can improve the number of detected photons and signal-to-noise ratio of velocity by forming a cavity. However, optimal improvements of number of detected photons and signal-to-noise ratio cannot be obtained simultaneously in our signal-recycled scheme owing to the walk-off effect. Furthermore, we find that the reflected light is relatively strong compared with the power-recycled scheme, which may increase the collection-detection efficiency in prospective relevant experiment.
基金supported by the Beijing Academy of Quantum Information Sciencessupported by the National Natural Science Foundation of China(Grant Nos.11674306 and 92065113)the University Synergy Innovation Program of Anhui Province(Grant No.GXXT-2022-039)。
文摘Wavefunction is a fundamental concept of quantum theory.Recent studies have shown surprisingly that wavefunction can be directly reconstructed via the measurement of weak value.The weak value based direct wavefunction reconstruction not only gives the operational meaning of wavefunction,but also provides the possibility of realizing holographic imaging with a totally new quantum approach.Here,we review the basic background knowledge of weak value based direct wavefunction reconstruction combined with recent experimental demonstrations.The main purpose of this work focuses on the idea of holographic imaging via direct wavefunction reconstruction.Since research on this topic is still in its early stage,we hope that this work can attract interest in the field of traditional holographic imaging.In addition,the wavefunction holographic imaging may find important applications in quantum information science.
基金Project supported by the National Natural Science Foundation of China(Grant No.11865017)the Introduction Program of High-Level Talents of Xinjiang Ministry of Science,China.
文摘Postselected von Neumann measurement characterized by postselection and weak value has been found to possess potential applications in quantum metrology and solved plenty of fundamental problems in quantum theory. As an application of this new measurement technique in quantum optics and quantum information processing, its effects on the features of single-mode radiation fields such as coherent state, squeezed vacuum state and Schrödinger cat sate are investigated by considering full-order effects of unitary evolution. The results show that the conditional probabilities of finding photons, second-order correlation functions, Qm-factors and squeezing effects of those states after the postselected measurement is significantly changed are comparable with the corresponding initial pointer states.
基金supported by the National Natural Science Fund Foundation of China(Grant No.11865017)。
文摘In this study,we give a new proposal to measure the temperature of the spin in a sample in a magnetic resonance force microscopy system by using postselected weak measurement,and investigating the Fisher information to estimate the precision of the scheme.We show that in a high temperature regime the temperature of the spin can be measured via a weak measurement technique with proper postselection and our scheme is able to increase the precision of temperature estimation.
