It has been claimed in the literature that impossibility of faster-than-light quantum communication has an origin of indistinguishability of ensembles with the same density matrix. We show that the two concepts are no...It has been claimed in the literature that impossibility of faster-than-light quantum communication has an origin of indistinguishability of ensembles with the same density matrix. We show that the two concepts are not related.We argue that even with an ideal single-atom-precision measurement, it is generally impossible to produce two ensembles with exactly the same density matrix; or to produce ensembles with the same density matrix, classical communication is necessary. Hence the impossibility of faster-than-light communication does not imply the indistinguishability of ensembles with the same density matrix.展开更多
In this paper, a quantum secure direct communication protocol using ensembles with the same density matrix is proposed. The two communication parties can realize the message transmission using this method through a qu...In this paper, a quantum secure direct communication protocol using ensembles with the same density matrix is proposed. The two communication parties can realize the message transmission using this method through a quantum channel, each bit of information can be transmitted using an ensemble and read out through global measurement. The eavesdropping behavior can be detected through the channel diagnoses.展开更多
The optimization of high density and concentrated-weight freights loading requires an even distribution of the freight's weight and unconcentrated loading on the floor of the car.Based on the characteristics of co...The optimization of high density and concentrated-weight freights loading requires an even distribution of the freight's weight and unconcentrated loading on the floor of the car.Based on the characteristics of concentrated-weight category freights,an improvement method is put forward to build freight towers and a greedy-construction algorithm is utilized based on heuristic information for the initial layout.Then a feasibility analysis is performed to judge if the balanced and unconcentrated loading constrains are reached.Through introducing optimization or adjustment methods,an overall optimal solution can be obtained.Experiments are conducted using data generated from real cases showing the effectiveness of our approach: volume utility ratio of 90.4% and load capacity utility ratio of 86.7% which is comparably even to the packing of the general freights.展开更多
文摘It has been claimed in the literature that impossibility of faster-than-light quantum communication has an origin of indistinguishability of ensembles with the same density matrix. We show that the two concepts are not related.We argue that even with an ideal single-atom-precision measurement, it is generally impossible to produce two ensembles with exactly the same density matrix; or to produce ensembles with the same density matrix, classical communication is necessary. Hence the impossibility of faster-than-light communication does not imply the indistinguishability of ensembles with the same density matrix.
基金The project supported by the National Fundamental Research Program of China under Grant No. 001CB309308, National Natural Science Foundation of China under Grant Nos. 60433050 and 10325521, and the SRDP program of the Ministry of Education, China
文摘In this paper, a quantum secure direct communication protocol using ensembles with the same density matrix is proposed. The two communication parties can realize the message transmission using this method through a quantum channel, each bit of information can be transmitted using an ensemble and read out through global measurement. The eavesdropping behavior can be detected through the channel diagnoses.
基金Project(71371193)supported by the National Natural Science Foundation of ChinaProjects(2005K1001,2007K1005)supported by Guangzhou-Shenzhen Railway Company Limited,China
文摘The optimization of high density and concentrated-weight freights loading requires an even distribution of the freight's weight and unconcentrated loading on the floor of the car.Based on the characteristics of concentrated-weight category freights,an improvement method is put forward to build freight towers and a greedy-construction algorithm is utilized based on heuristic information for the initial layout.Then a feasibility analysis is performed to judge if the balanced and unconcentrated loading constrains are reached.Through introducing optimization or adjustment methods,an overall optimal solution can be obtained.Experiments are conducted using data generated from real cases showing the effectiveness of our approach: volume utility ratio of 90.4% and load capacity utility ratio of 86.7% which is comparably even to the packing of the general freights.
