A methodology is presented to obtain the basis of qudits which are admissible to quantum Fourier transform(QFT)in the sense that the set of such kets are related by the QFT in the same way as the kets of the computati...A methodology is presented to obtain the basis of qudits which are admissible to quantum Fourier transform(QFT)in the sense that the set of such kets are related by the QFT in the same way as the kets of the computational basis.We first study this method for qubits to characterize the ensemble that works for the Hadamard transformation(QFT for two dimension).In this regard we identify certain incompleteness in the result of Maitra and Parashar(Int.J.Quantum Inform.4(2006)653).Next we characterize the ensemble of qutrits for which QFT is possible.Further,some theoretical results related to higher dimensions are also discussed.Considering the unitary matrix Un related to QFT,the issue boils down to the problem of characterizing matrices that commute with Un.展开更多
In 2018, Niu et al. [1] proposed a measurement-device-independent quantum secure direct communication(MDI-QSDC) protocol and quantum dialogue(MDI-QD) protocol using Einstein-Podolsky-Rosen(EPR) pairs. In their protoco...In 2018, Niu et al. [1] proposed a measurement-device-independent quantum secure direct communication(MDI-QSDC) protocol and quantum dialogue(MDI-QD) protocol using Einstein-Podolsky-Rosen(EPR) pairs. In their protocols, the two legitimate parties prepare two sets of EPR pairs in their locations, and send the partner qubits of their EPR pairs to an untrusted third party(UTP). Here we analyze these protocols and show that 50% of the information about the secret message bits is leaked out in both the protocols.展开更多
文摘A methodology is presented to obtain the basis of qudits which are admissible to quantum Fourier transform(QFT)in the sense that the set of such kets are related by the QFT in the same way as the kets of the computational basis.We first study this method for qubits to characterize the ensemble that works for the Hadamard transformation(QFT for two dimension).In this regard we identify certain incompleteness in the result of Maitra and Parashar(Int.J.Quantum Inform.4(2006)653).Next we characterize the ensemble of qutrits for which QFT is possible.Further,some theoretical results related to higher dimensions are also discussed.Considering the unitary matrix Un related to QFT,the issue boils down to the problem of characterizing matrices that commute with Un.
文摘In 2018, Niu et al. [1] proposed a measurement-device-independent quantum secure direct communication(MDI-QSDC) protocol and quantum dialogue(MDI-QD) protocol using Einstein-Podolsky-Rosen(EPR) pairs. In their protocols, the two legitimate parties prepare two sets of EPR pairs in their locations, and send the partner qubits of their EPR pairs to an untrusted third party(UTP). Here we analyze these protocols and show that 50% of the information about the secret message bits is leaked out in both the protocols.
