In Otsuka's view of nuclear rotations neutrons and protons are not rotating around a common axis,but rather around separate axis.In this letter,we pointed out that this invalidates the geometrical interpretation o...In Otsuka's view of nuclear rotations neutrons and protons are not rotating around a common axis,but rather around separate axis.In this letter,we pointed out that this invalidates the geometrical interpretation of F-spin structure of the neutron-proton interacting boson model,where the angle between the axis of symmetries of neutron ellipsoid and proton ellipsoid is used to determine whether a state is F-spin symmetric or mixed symmetric.展开更多
By using quantum bang-bang control technique,we studied the suppression of amplitude damping,or energy dissipation,in a three-level atom in various configurations.We have explicitly given the bang-bang control groups ...By using quantum bang-bang control technique,we studied the suppression of amplitude damping,or energy dissipation,in a three-level atom in various configurations.We have explicitly given the bang-bang control groups in three different configurations,and the pulse sequences for these bang-bang control operations.展开更多
An entanglement measure,multiple entropy measures(MEMS) was proposed recently by using the geometric mean of partial entropies over all possible i-body combinations of the quantum system.In this work,we study the aver...An entanglement measure,multiple entropy measures(MEMS) was proposed recently by using the geometric mean of partial entropies over all possible i-body combinations of the quantum system.In this work,we study the average subsystem von Neumann entropies of the linear cluster state and investigated the quantum entanglement of linear cluster states in terms of MEMS.Explicit results with specific particle numbers are calculated,and some analytical results are given for systems with arbitrary particle numbers.Compared with other example quantum states such as the GHZ states and W states,the linear cluster states are "more entangled" in terms of MEMS,namely their averaged entropies are larger than the GHZ states and W states.展开更多
Three-body interaction plays an important role in many-body physics,and quantum computer is efficient in simulating many-body interactions. We have experimentally demonstrated the general three-body interactions in a ...Three-body interaction plays an important role in many-body physics,and quantum computer is efficient in simulating many-body interactions. We have experimentally demonstrated the general three-body interactions in a three-qubit nuclear magnetic resonance ensemble quantum computer. Using a nuclear magnetic resonance computer we implemented general forms of three-body interactions including σ 1x σ z2 σ x3 and σ 1x σ z2 σ y3 . The results show good agreement between theory and experiment. We have also given a concise and practical formula for a general n-body interaction in terms of one-and two-body interactions.展开更多
The four-body interaction plays an important role in many-body systems, and it can exhibit interesting phase transition behaviors. In this letter, we report the experimental demonstration of a four-body interaction in...The four-body interaction plays an important role in many-body systems, and it can exhibit interesting phase transition behaviors. In this letter, we report the experimental demonstration of a four-body interaction in a four-qubit nuclear magnetic resonance quantum information processor. The strongly modulating pulse is used to implement spin selective excitation. The results show a good agreement between theory and experiment.展开更多
In this work, we demonstrated a fixed-point quantum search algorithm in the nuclear magnetic resonance (NMR) system. We constructed the pulse sequences for the pivotal operations in the quantum search protocol. The ex...In this work, we demonstrated a fixed-point quantum search algorithm in the nuclear magnetic resonance (NMR) system. We constructed the pulse sequences for the pivotal operations in the quantum search protocol. The experimental results agree well with the theoretical predictions. The generalization of the scheme to the arbitrary number of qubits has also been given.展开更多
We report an NMR experimental realization of a rapid quantum deletion algorithm that deletes marked states in an unsorted database.Unlike classical deletion,where search and deletion are equivalent,quantum deletion ca...We report an NMR experimental realization of a rapid quantum deletion algorithm that deletes marked states in an unsorted database.Unlike classical deletion,where search and deletion are equivalent,quantum deletion can be implemented with only a single query,which achieves exponential speed-up compared to the optimal classical analog.In the experimental realization,the GRAPE algorithm was used to obtain an optimized NMR pulse sequence,and the efficient method of maximum-likelihood has been used to reconstruct the experimental output state.展开更多
The past decade or two has witnessed tremendous progress in theory and practice of quantum control technologies.Bridging different scientific disciplines ranging from fundamental particle physics to nanotechnology,the...The past decade or two has witnessed tremendous progress in theory and practice of quantum control technologies.Bridging different scientific disciplines ranging from fundamental particle physics to nanotechnology,the goal of quantum control has been to develop effective and efficient tools for common analysis and design,but more importantly would pave the way for future technological applications.This article briefly reviews basic quantum control theory from the perspective of modeling,analysis and design,as well as considers future research directions.展开更多
In this paper,we present an efficient purification scheme that improves the efficiency of entanglement purification of the recently proposed entanglement purification scheme for doubly entangled photon states (Phys.Re...In this paper,we present an efficient purification scheme that improves the efficiency of entanglement purification of the recently proposed entanglement purification scheme for doubly entangled photon states (Phys.Rev.A,2008,77:042315).This modified scheme contains the bit-flip error correction where all the photon pairs can be kept while all the bit-flip errors are corrected and the entanglement purification of phase-flip errors where a wavelength conversion process is used.This scheme has the advantage of high efficiency and a much lower minimum fidelity of the original state.It works under existing technology.展开更多
Quantum communication and quantum computation are two major branches of quantum information.In quantum communication,principles of quantum physics provide us with the capability of on-site detection of eavesdropping(O...Quantum communication and quantum computation are two major branches of quantum information.In quantum communication,principles of quantum physics provide us with the capability of on-site detection of eavesdropping(ODE).In quantum key distribution,random numbers are distributed between two remote parties.If an eavesdropper is found,then the communicated data will be discarded.If no eavesdropper is found,the transmitted data is then post-processed to a very high security level and used as keys.Quantum key distribution could not communicate secret message directly,because it cannot obliterate the information leakage before eavesdropper detection(OILBED).In quantum secure direct communication,not only eavesdropper can be found on-site,but also the obliteration of information leakage before eavesdropper detection can be realized.展开更多
基金Supported by the China State Education Commission and the Fund for Fundamental Research of Tsinghua University.
文摘In Otsuka's view of nuclear rotations neutrons and protons are not rotating around a common axis,but rather around separate axis.In this letter,we pointed out that this invalidates the geometrical interpretation of F-spin structure of the neutron-proton interacting boson model,where the angle between the axis of symmetries of neutron ellipsoid and proton ellipsoid is used to determine whether a state is F-spin symmetric or mixed symmetric.
基金the National Natural Science Foundation of China(Grant No.10547003)the Key Project of Chinese Ministry of Education(Grant No.306020)Chifeng College Scientific Research Fund(Grant No.ZRZD200604)
文摘By using quantum bang-bang control technique,we studied the suppression of amplitude damping,or energy dissipation,in a three-level atom in various configurations.We have explicitly given the bang-bang control groups in three different configurations,and the pulse sequences for these bang-bang control operations.
基金supported by the National Natural Science Foundation of China (10874 098,11175094)the National Basic Research Program of China (2009CB929402,2011CB9216002)
文摘An entanglement measure,multiple entropy measures(MEMS) was proposed recently by using the geometric mean of partial entropies over all possible i-body combinations of the quantum system.In this work,we study the average subsystem von Neumann entropies of the linear cluster state and investigated the quantum entanglement of linear cluster states in terms of MEMS.Explicit results with specific particle numbers are calculated,and some analytical results are given for systems with arbitrary particle numbers.Compared with other example quantum states such as the GHZ states and W states,the linear cluster states are "more entangled" in terms of MEMS,namely their averaged entropies are larger than the GHZ states and W states.
基金the National Natural Science Foundation of China (Grant Nos. 10374010 and 10325521) the National Basic Research Program of China (Grant No. 2006CB921106)
文摘Three-body interaction plays an important role in many-body physics,and quantum computer is efficient in simulating many-body interactions. We have experimentally demonstrated the general three-body interactions in a three-qubit nuclear magnetic resonance ensemble quantum computer. Using a nuclear magnetic resonance computer we implemented general forms of three-body interactions including σ 1x σ z2 σ x3 and σ 1x σ z2 σ y3 . The results show good agreement between theory and experiment. We have also given a concise and practical formula for a general n-body interaction in terms of one-and two-body interactions.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10775076, 10874098)National Basic Research Program of China (Grant Nos. 2006CB921106, 2009CB929402)Specialized Research Fund for the Doctoral Program of Education Ministry of China (Grant No. 20060003048)
文摘The four-body interaction plays an important role in many-body systems, and it can exhibit interesting phase transition behaviors. In this letter, we report the experimental demonstration of a four-body interaction in a four-qubit nuclear magnetic resonance quantum information processor. The strongly modulating pulse is used to implement spin selective excitation. The results show a good agreement between theory and experiment.
基金supported by the SRFPD Program of Education Ministry ofChina (Grant No. 20090002110064)the National Natural Science Foundation of China (Grant No. 10874098)the National Basic Research Program of China (Grant Nos. 2009CB929402 and 2011CB921602)
文摘In this work, we demonstrated a fixed-point quantum search algorithm in the nuclear magnetic resonance (NMR) system. We constructed the pulse sequences for the pivotal operations in the quantum search protocol. The experimental results agree well with the theoretical predictions. The generalization of the scheme to the arbitrary number of qubits has also been given.
基金supported by the National Natural Science Foundation of China(Grant Nos.11175094 and 91221205)the National Basic Research Program of China(Grant No.2011CB9216002)
文摘We report an NMR experimental realization of a rapid quantum deletion algorithm that deletes marked states in an unsorted database.Unlike classical deletion,where search and deletion are equivalent,quantum deletion can be implemented with only a single query,which achieves exponential speed-up compared to the optimal classical analog.In the experimental realization,the GRAPE algorithm was used to obtain an optimized NMR pulse sequence,and the efficient method of maximum-likelihood has been used to reconstruct the experimental output state.
基金supported by the National Natural Science Foundation of China(60904034,61174084and61134008)Tsinghua National Laboratory for Information Science and Technology(TNList)Cross-discipline Foundation
文摘The past decade or two has witnessed tremendous progress in theory and practice of quantum control technologies.Bridging different scientific disciplines ranging from fundamental particle physics to nanotechnology,the goal of quantum control has been to develop effective and efficient tools for common analysis and design,but more importantly would pave the way for future technological applications.This article briefly reviews basic quantum control theory from the perspective of modeling,analysis and design,as well as considers future research directions.
基金Supported by the National Natural Science Foundation of China(Grant Nos.10604008,10874098,10775076)the National Fundamental Research Program of China(Grant No.2006CB921106)
文摘In this paper,we present an efficient purification scheme that improves the efficiency of entanglement purification of the recently proposed entanglement purification scheme for doubly entangled photon states (Phys.Rev.A,2008,77:042315).This modified scheme contains the bit-flip error correction where all the photon pairs can be kept while all the bit-flip errors are corrected and the entanglement purification of phase-flip errors where a wavelength conversion process is used.This scheme has the advantage of high efficiency and a much lower minimum fidelity of the original state.It works under existing technology.
文摘Quantum communication and quantum computation are two major branches of quantum information.In quantum communication,principles of quantum physics provide us with the capability of on-site detection of eavesdropping(ODE).In quantum key distribution,random numbers are distributed between two remote parties.If an eavesdropper is found,then the communicated data will be discarded.If no eavesdropper is found,the transmitted data is then post-processed to a very high security level and used as keys.Quantum key distribution could not communicate secret message directly,because it cannot obliterate the information leakage before eavesdropper detection(OILBED).In quantum secure direct communication,not only eavesdropper can be found on-site,but also the obliteration of information leakage before eavesdropper detection can be realized.