Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal deco...Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal decoy state protocol with a heralded single photon source （HSPS） for QKD is presented. The protocol is based on 4 states with different intensities. i.e. one signal state and three decoy states. The signal state is for generating keys; the decoy states are for detecting the eavesdropping and estimating the fraction of single-photon and two-photon pulses. We have discussed three cases of this protocol, i.e. the general case, the optimal case and the special case. Moreover, the final key rate over transmission distance is simulated. For the low dark count of the HSPS and the utilization of the two-photon pulses, our protocol has a higher key rate and a longer transmission distance than any other decoy state protocol.展开更多
Combining the passive decoy-state idea with the active decoy-state idea, a non-orthogonal （SARG04） decoy-state protocol with one vacuum and two weak decoy states is introduced based on a heralded pair coherent state...Combining the passive decoy-state idea with the active decoy-state idea, a non-orthogonal （SARG04） decoy-state protocol with one vacuum and two weak decoy states is introduced based on a heralded pair coherent state photon source for quantum key distribution. Two special cases of this protocol are deduced, i.e., a one-vacuum-and-one-weak-decoy-state protocol and a one-weak-decoy-state protocol. In these protocols, the sender prepares decoy states actively, which avoids the crude estimation of parameters in the SARG04 passive decoy-state method. With the passive decoy-state idea, the detection events on Bob＇s side that are non-triggered on Alice＇s side are not discarded, but used to estimate the fractions of single-photon and two-photon pulses, which offsets the limitation of the detector＇s low efficiency and overcomes the shortcoming that the performance of the active decoy-state protocol critically depends on the efficiency of detector. The simulation results show that the combination of the active and passive decoy-state ideas increases the key generation rate. With a one-vacuum-and-two-weak-decoy-state protocol, one can achieve a key generation rate that is close to the theoretical limit of an infinite decoy-state protocol. The performance of the other two protocols is a little less than with the former, but the implementation is easier. Under the same condition of implementation, higher key rates can be obtained with our protocols than with existing methods.展开更多
Recently an f -deformed Fock space which is spanned by ｜ n λ was introduced. These bases are the eigenstates of a deformed non-Hermitian Hamiltonian. In this contribution, we will use rather new nonorthogonal basis ...Recently an f -deformed Fock space which is spanned by ｜ n λ was introduced. These bases are the eigenstates of a deformed non-Hermitian Hamiltonian. In this contribution, we will use rather new nonorthogonal basis vectors for the construction of coherent and squeezed states, which in special case lead to the earlier known states. For this purpose, we first generalize the previously introduced Fock space spanned by ｜ n λ bases, to a new one, spanned by extended two-parameters bases ｜ n λ 1 ,λ 2 . These bases are now the eigenstates of a non-Hermitian Hamiltonian H λ 1 ,λ 2 = a λ 1 ,λ 2 a ＋ 1 2 , where a λ 1 ,λ 2 = a ＋ λ 1 a ＋ λ 2 and a are, respectively, the deformed creation and ordinary bosonic annihilation operators. The bases ｜ n λ 1 ,λ 2 are nonorthogonal （squeezed states）, but normalizable. Then, we deduce the new representations of coherent and squeezed states in our two-parameter Fock space. Finally, we discuss the quantum statistical properties, as well as the non-classical properties of the obtained states numerically.展开更多
基于准单光子光源HSPS(heralded single photon source),推导了非正交(SARG04)三诱惑态(真空态和2个弱光强态)量子密钥分配方案。为了降低实现难度,将2个弱光强态合并,提出了简化的二诱惑态方案(真空态和一个弱光强态)。此方案将主动诱...基于准单光子光源HSPS(heralded single photon source),推导了非正交(SARG04)三诱惑态(真空态和2个弱光强态)量子密钥分配方案。为了降低实现难度,将2个弱光强态合并,提出了简化的二诱惑态方案(真空态和一个弱光强态)。此方案将主动诱惑态方案和被动诱惑态方案相结合,不舍弃接收者检测结果中发送端探测器没有响应的脉冲集合,而是用来估计参量和生成密钥。数值仿真表明,被动诱惑态思想的加入,提高了密钥生成效率;二诱惑态方案的密钥生成效率非常趋近于无穷诱惑态方案的理论极限值;在实现难度相同的条件下,SARG04协议的密钥生成效率和传输距离都高于BB84协议。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 60578055)the State Key Development Program for Basic Research of China (Grant No 2007CB307001)
文摘Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal decoy state protocol with a heralded single photon source （HSPS） for QKD is presented. The protocol is based on 4 states with different intensities. i.e. one signal state and three decoy states. The signal state is for generating keys; the decoy states are for detecting the eavesdropping and estimating the fraction of single-photon and two-photon pulses. We have discussed three cases of this protocol, i.e. the general case, the optimal case and the special case. Moreover, the final key rate over transmission distance is simulated. For the low dark count of the HSPS and the utilization of the two-photon pulses, our protocol has a higher key rate and a longer transmission distance than any other decoy state protocol.
基金Project supported by the National High Technology Research and Development Program of China (Grant No. 2011AA7014061)the Science Foundation of Naval University of Engineering, China (Grant No. HGDQNJJ11022)
文摘Combining the passive decoy-state idea with the active decoy-state idea, a non-orthogonal （SARG04） decoy-state protocol with one vacuum and two weak decoy states is introduced based on a heralded pair coherent state photon source for quantum key distribution. Two special cases of this protocol are deduced, i.e., a one-vacuum-and-one-weak-decoy-state protocol and a one-weak-decoy-state protocol. In these protocols, the sender prepares decoy states actively, which avoids the crude estimation of parameters in the SARG04 passive decoy-state method. With the passive decoy-state idea, the detection events on Bob＇s side that are non-triggered on Alice＇s side are not discarded, but used to estimate the fractions of single-photon and two-photon pulses, which offsets the limitation of the detector＇s low efficiency and overcomes the shortcoming that the performance of the active decoy-state protocol critically depends on the efficiency of detector. The simulation results show that the combination of the active and passive decoy-state ideas increases the key generation rate. With a one-vacuum-and-two-weak-decoy-state protocol, one can achieve a key generation rate that is close to the theoretical limit of an infinite decoy-state protocol. The performance of the other two protocols is a little less than with the former, but the implementation is easier. Under the same condition of implementation, higher key rates can be obtained with our protocols than with existing methods.
文摘Recently an f -deformed Fock space which is spanned by ｜ n λ was introduced. These bases are the eigenstates of a deformed non-Hermitian Hamiltonian. In this contribution, we will use rather new nonorthogonal basis vectors for the construction of coherent and squeezed states, which in special case lead to the earlier known states. For this purpose, we first generalize the previously introduced Fock space spanned by ｜ n λ bases, to a new one, spanned by extended two-parameters bases ｜ n λ 1 ,λ 2 . These bases are now the eigenstates of a non-Hermitian Hamiltonian H λ 1 ,λ 2 = a λ 1 ,λ 2 a ＋ 1 2 , where a λ 1 ,λ 2 = a ＋ λ 1 a ＋ λ 2 and a are, respectively, the deformed creation and ordinary bosonic annihilation operators. The bases ｜ n λ 1 ,λ 2 are nonorthogonal （squeezed states）, but normalizable. Then, we deduce the new representations of coherent and squeezed states in our two-parameter Fock space. Finally, we discuss the quantum statistical properties, as well as the non-classical properties of the obtained states numerically.
文摘基于准单光子光源HSPS(heralded single photon source),推导了非正交(SARG04)三诱惑态(真空态和2个弱光强态)量子密钥分配方案。为了降低实现难度,将2个弱光强态合并,提出了简化的二诱惑态方案(真空态和一个弱光强态)。此方案将主动诱惑态方案和被动诱惑态方案相结合,不舍弃接收者检测结果中发送端探测器没有响应的脉冲集合,而是用来估计参量和生成密钥。数值仿真表明,被动诱惑态思想的加入,提高了密钥生成效率;二诱惑态方案的密钥生成效率非常趋近于无穷诱惑态方案的理论极限值;在实现难度相同的条件下,SARG04协议的密钥生成效率和传输距离都高于BB84协议。
