We present a scheme for probabilistically teleporting an unknown three-level bipartite entangled state by using a partial entangled three-level bipartite state as quantum channel This scheme can be directly generalize...We present a scheme for probabilistically teleporting an unknown three-level bipartite entangled state by using a partial entangled three-level bipartite state as quantum channel This scheme can be directly generalized to probabilistically teleport an unknown three-level k-particle entangled state by a partial three-level bipartite entangled state. A11 kinds of unitary transformations are given in detail We calculate the successful total probability and the total classical communication cost required for this scheme.展开更多
The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world？ In this paper, we calculate the change of entropy in T.D. Kieu＇s model for quantum...The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world？ In this paper, we calculate the change of entropy in T.D. Kieu＇s model for quantum heat engine （QHE） and prove the broad validity of the second law of thermodynamics. It is shown that the entropy of the quantum heat engine neither decreases in a whole cycle, nor decreases in either stage of the cycle. The second law of thermodynamics still holds in this QHE model. Moreover, although the modified quantum heat engine is capable of extracting more work, its efficiency does not improve at all. It is neither beyond the efficiency of T.D. Kieu＇s initial model,nor greater than the reversible Carnot efficiency.展开更多
The relative entropy of entanglement of a mixed stateσfor a bipartite quantum system can be defined as the minimum of the quantum relative entropy over the set of completely disentangled states.Vedral et al.[Phys.Rev...The relative entropy of entanglement of a mixed stateσfor a bipartite quantum system can be defined as the minimum of the quantum relative entropy over the set of completely disentangled states.Vedral et al.[Phys.Rev.A 57(1998)1619]have recently proposed a numerical method to get the relative entropy of entanglement Ere for two-qubit systems.This paper shows that the convex programming method can be applied to calculate Ere of two-qubit systems analytically,and discusses the conditions under which the method can be adopted.展开更多
基金The project supported by National Natural Science Foundation of China under Grant No.60674040China Postdoctoral Science Foundation
文摘We present a scheme for probabilistically teleporting an unknown three-level bipartite entangled state by using a partial entangled three-level bipartite state as quantum channel This scheme can be directly generalized to probabilistically teleport an unknown three-level k-particle entangled state by a partial three-level bipartite entangled state. A11 kinds of unitary transformations are given in detail We calculate the successful total probability and the total classical communication cost required for this scheme.
基金The project supported by National Natural Science Foundation of China under Grant No. 10404039
文摘The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world？ In this paper, we calculate the change of entropy in T.D. Kieu＇s model for quantum heat engine （QHE） and prove the broad validity of the second law of thermodynamics. It is shown that the entropy of the quantum heat engine neither decreases in a whole cycle, nor decreases in either stage of the cycle. The second law of thermodynamics still holds in this QHE model. Moreover, although the modified quantum heat engine is capable of extracting more work, its efficiency does not improve at all. It is neither beyond the efficiency of T.D. Kieu＇s initial model,nor greater than the reversible Carnot efficiency.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19975068.
文摘The relative entropy of entanglement of a mixed stateσfor a bipartite quantum system can be defined as the minimum of the quantum relative entropy over the set of completely disentangled states.Vedral et al.[Phys.Rev.A 57(1998)1619]have recently proposed a numerical method to get the relative entropy of entanglement Ere for two-qubit systems.This paper shows that the convex programming method can be applied to calculate Ere of two-qubit systems analytically,and discusses the conditions under which the method can be adopted.
