Based on the quantum information theory, we have investigated the entropy squeezing of a moving two-level atom interacting with the coherent field via the quantum mechanical channel of the two-photon process. The resu...Based on the quantum information theory, we have investigated the entropy squeezing of a moving two-level atom interacting with the coherent field via the quantum mechanical channel of the two-photon process. The results are compared with those of atomic squeezing based on the Heisenberg uncertainty relation. The influences of the atomic motion and field-mode structure parameter on the atomic entropy squeezing and on the control of noise of the quantum mechanical channel via the two-photon process are examined. Our results show that the squeezed period, duration of optimal entropy squeezing of a two-level atom and the noise of the quantum mechanical channel can be controlled by appropriately choosing the atomic motion and the field-mode structure parameter, respectively. The quantum mechanical channel of two-photon process is an ideal channel for quantum information （atomic quantum state） transmission. Quantum information entropy is a remarkably accurate measure of the atomic squeezing.展开更多
For a compact quantum key distribution (QKD) sender for the polarization encoding BB84 protocol, an eavesdropper could take a side-channel attack by measuring the spatial information of photons to infer their polariza...For a compact quantum key distribution (QKD) sender for the polarization encoding BB84 protocol, an eavesdropper could take a side-channel attack by measuring the spatial information of photons to infer their polarizations. The possibility of this attack can be reduced by introducing an aperture in the QKD sender, however, the effect of the aperture on the QKD security lacks of quantitative analysis. In this paper, we analyze the mutual information between the actual keys encoded at this QKD sender and the inferred keys at the eavesdropper (Eve), demonstrating the effect of the aperture to eliminate the spatial side-channel information quantitatively. It shows that Eve’s potential on eavesdropping spatial side-channel information is totally dependent on the optical design of the QKD sender, including the source arrangement and the aperture. The height of compact QKD senders with integrated light-emitting diode (LED) arrays could be controlled under several millimeters, showing great potential on applications in portable equipment.展开更多
Based on the resource theory for quantifying the coherence of quantum channels, we introduce a new coherence quantifier for quantum channels via maximum relative entropy. We prove that the maximum relative entropy for...Based on the resource theory for quantifying the coherence of quantum channels, we introduce a new coherence quantifier for quantum channels via maximum relative entropy. We prove that the maximum relative entropy for coherence of quantum channels is directly related to the maximally coherent channels under a particular class of superoperations, which results in an operational interpretation of the maximum relative entropy for coherence of quantum channels. We also introduce the conception of subsuperchannels and sub-superchannel discrimination. For any quantum channels, we show that the advantage of quantum channels in sub-superchannel discrimination can be exactly characterized by the maximum relative entropy of coherence for quantum channels. Similar to the maximum relative entropy of coherence for channels, the robustness of coherence for quantum channels has also been investigated. We show that the maximum relative entropy of coherence for channels provides new operational interpretations of robustness of coherence for quantum channels and illustrates the equivalence of the dephasing-covariant superchannels,incoherent superchannels, and strictly incoherent superchannels in these two operational tasks.展开更多
设Hm 是维数为m的复希尔伯特空间,S(Hm ■Hn )是作用在复双体希尔伯特空间H m ■H n 上的所有量子态的全体, Ssep (Hm■Hn)是所有可分量子态做成的S(Hm■Hn)的凸子集,Ф: S(Hm■Hn ) S(Hm■Hn )是量子信道且Ф(S sep■(H m■ H n ))=S s...设Hm 是维数为m的复希尔伯特空间,S(Hm ■Hn )是作用在复双体希尔伯特空间H m ■H n 上的所有量子态的全体, Ssep (Hm■Hn)是所有可分量子态做成的S(Hm■Hn)的凸子集,Ф: S(Hm■Hn ) S(Hm■Hn )是量子信道且Ф(S sep■(H m■ H n ))=S sep (H m■ H n ),那么Ф保持 von Neumann 熵S(t ρ+(1-t)σ)=S(tФ(ρ)+(1-t)Ф(σ)),■ t∈[0, 1],■ρ,σ∈S sep (H m■H n )当且仅当在H m ,H n 上分别存在酉算子或共轭酉算子 U m , V n ,使得Ф(ρ)=( U m■ V n )ρ( U m■ V n )^*,■ρ∈S sep (H m ■H n ).展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10374025）, the Natural Science Foundation of Hunan Province, China （Grant No 05JJ30004） and the Scientific Research Fund of Hunan Provincial Education Department, China （Grant No 03c543）
文摘Based on the quantum information theory, we have investigated the entropy squeezing of a moving two-level atom interacting with the coherent field via the quantum mechanical channel of the two-photon process. The results are compared with those of atomic squeezing based on the Heisenberg uncertainty relation. The influences of the atomic motion and field-mode structure parameter on the atomic entropy squeezing and on the control of noise of the quantum mechanical channel via the two-photon process are examined. Our results show that the squeezed period, duration of optimal entropy squeezing of a two-level atom and the noise of the quantum mechanical channel can be controlled by appropriately choosing the atomic motion and the field-mode structure parameter, respectively. The quantum mechanical channel of two-photon process is an ideal channel for quantum information （atomic quantum state） transmission. Quantum information entropy is a remarkably accurate measure of the atomic squeezing.
基金supported by the National Key Research and Development Program of China under Grant No.2017YFA0303704National Natural Science Foundation of China under Grants No.61575102,No.61671438,No.61875101,and No.61621064+1 种基金Beijing Natural Science Foundation under Grant No.Z180012Beijing Academy of Quantum Information Sciences under Grant No.Y18G26
文摘For a compact quantum key distribution (QKD) sender for the polarization encoding BB84 protocol, an eavesdropper could take a side-channel attack by measuring the spatial information of photons to infer their polarizations. The possibility of this attack can be reduced by introducing an aperture in the QKD sender, however, the effect of the aperture on the QKD security lacks of quantitative analysis. In this paper, we analyze the mutual information between the actual keys encoded at this QKD sender and the inferred keys at the eavesdropper (Eve), demonstrating the effect of the aperture to eliminate the spatial side-channel information quantitatively. It shows that Eve’s potential on eavesdropping spatial side-channel information is totally dependent on the optical design of the QKD sender, including the source arrangement and the aperture. The height of compact QKD senders with integrated light-emitting diode (LED) arrays could be controlled under several millimeters, showing great potential on applications in portable equipment.
基金supported by the National Natural Science Foundation of China(Grant Nos.11847209,61727801,and 12075159)the China Postdoctoral Science Foundation(Grant No.2019M650811)+4 种基金the China Scholarship Council(Grant No.201904910005)Shenzhen Institute for Quantum Science and Engineering,Southern University of Science and Technology(Grant No.SIQSE202001)Beijing Natural Science Foundation(Grant No.Z190005)the Academician Innovation Platform of Hainan ProvinceAcademy for Multidisciplinary Studies,Capital Normal University。
文摘Based on the resource theory for quantifying the coherence of quantum channels, we introduce a new coherence quantifier for quantum channels via maximum relative entropy. We prove that the maximum relative entropy for coherence of quantum channels is directly related to the maximally coherent channels under a particular class of superoperations, which results in an operational interpretation of the maximum relative entropy for coherence of quantum channels. We also introduce the conception of subsuperchannels and sub-superchannel discrimination. For any quantum channels, we show that the advantage of quantum channels in sub-superchannel discrimination can be exactly characterized by the maximum relative entropy of coherence for quantum channels. Similar to the maximum relative entropy of coherence for channels, the robustness of coherence for quantum channels has also been investigated. We show that the maximum relative entropy of coherence for channels provides new operational interpretations of robustness of coherence for quantum channels and illustrates the equivalence of the dephasing-covariant superchannels,incoherent superchannels, and strictly incoherent superchannels in these two operational tasks.
文摘设Hm 是维数为m的复希尔伯特空间,S(Hm ■Hn )是作用在复双体希尔伯特空间H m ■H n 上的所有量子态的全体, Ssep (Hm■Hn)是所有可分量子态做成的S(Hm■Hn)的凸子集,Ф: S(Hm■Hn ) S(Hm■Hn )是量子信道且Ф(S sep■(H m■ H n ))=S sep (H m■ H n ),那么Ф保持 von Neumann 熵S(t ρ+(1-t)σ)=S(tФ(ρ)+(1-t)Ф(σ)),■ t∈[0, 1],■ρ,σ∈S sep (H m■H n )当且仅当在H m ,H n 上分别存在酉算子或共轭酉算子 U m , V n ,使得Ф(ρ)=( U m■ V n )ρ( U m■ V n )^*,■ρ∈S sep (H m ■H n ).
