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1.
The widths of the spectator momentum distributions in several nuclei, which have been used as Trojan Horses, have been obtained as a function of the transferred momentum. Applications of Trojan Horse method will also be discussed.  相似文献   

2.
The study of energy production and nucleosynthesis in stars requires an increasingly precise knowledge of the nuclear reaction rates at the energies of interest. To overcome the experimental difficulties arising from the small cross sections at those energies and from the presence of the electron screening, the Trojan Horse Method has been introduced. The method provides a valid alternative path to measure unscreened low-energy cross sections of reactions between charged particles, and to retrieve information on the electron screening potential when ultra-low energy direct measurements are available.  相似文献   

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Quantum Key Distribution against Trojan Horse Attacks   总被引:1,自引:0,他引:1       下载免费PDF全文
蔡庆宇  吕桦 《中国物理快报》2007,24(5):1154-1157
Realistic experimental apparatus of quantum cryptography are imperfect, which may be utilized by a potential eavesdropper to eavesdrop on the communication. We show that quantum communication may be improved with quantum teleportation and entanglement swapping, which is robustly secure against the most general Trojan horse attacks. Our scheme is not an improvement of the communication apparatus, but the improvement of quantum communication protocol itself. We show that our modified schemes may be implemented with current technology.  相似文献   

5.
Recently, Yang and Hwang (Quantum Inf. Process. 13(3): 781–794, 19) proposed two fault-tolerant QKD protocols based on their proposed coding functions for resisting the collective noise, and their QKD protocols are free from Trojan horse attack without employing any specific detecting devices (e.g., photon number splitter (PNS) and wavelength filter). By using four-particle Greenberger-Horne-Zeilinger (GHZ) state and four-particle GHZ-like state in their proposed coding functions, Yang and Hwang’s QKD protocols can resist each kind of the collective noise–collective-dephasing noise, collective-rotation noise. However, their proposed coding function can be improved by the utilization of three-particle GHZ state (three-particle GHZ-like state) instead of four-particle GHZ state (four-particle GHZ-like state) that will eventually reduce the consumption of the qubits. As a result, this study proposed the improved version of Yang and Hwang’s coding functions to enhance the qubit efficiency of their schemes from 20 % to 22 %.  相似文献   

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With the introduction of the Trojan Horse Method, nuclear cross sections between charged particles at astrophysical energies can now be measured. Here the basic features of the method are recalled together with recent results relevant for Nuclear Astrophysics. New applications in connection with plasma physics and industrial energy production are discussed.  相似文献   

8.
Palash B Pal 《Pramana》1999,53(6):1053-1059
I discuss some compelling suggestions about particles which could be the dark matter in the Universe, with special attention to experimental searches for them.  相似文献   

9.
Journal of Experimental and Theoretical Physics - Early proofs of key secrecy in quantum cryptography systems were based on the assumption that the transmitting and receiving stations are...  相似文献   

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Manuel Drees 《Pramana》1998,51(1-2):87-106
This write-up gives a rather elementary introduction into particle physics aspects of the cosmological dark matter puzzle. A fairly comprehensive list of possible candidates is given; in each case the production mechanism and possible ways to detect them (if any) are described. I then describe detection of the, in my view, most promising candidates, weakly interacting massive particles or WIMPs, in slightly more detail. The main emphasis will be on recent developments.  相似文献   

12.
为克服低能带电粒子核反应截面直接测量中所遇到的库仑位垒和电子屏蔽效应带来的困难,试用基于准自由反应机制的特洛伊木马方法,在意大利南部国家核物理实验室的15MV串列加速器上,通过^2H(^9Be,α^6Li)n核反应对^9Be(p,α)^6Li在低能区(Ecm=0-1000kev)的裸核反应截面做了间接测量,并将测量结果与直接测量数据进行了比较。  相似文献   

13.
This paper suggests a principle to find a unitary operator U which transforms non-physical quantity,zero-potential Hamiltonian Ho, into true physical quantity UHoU for a charged particle in classical electromagneticfield, and puts forward a unified form of constructing gauge-independent transition probabilities in this case. Differentmethods correspond to different unitary operators which satisfy the above-mentioned principle.  相似文献   

14.
We give a general method of deriving statistical limit theorems, such as the central limit theorem and its functional version, in the setting of ergodic measure preserving transformations. This method is applicable in situations where the iterates of discrete time maps display a polynomial decay of correlations.  相似文献   

15.
We investigate stationary distributions of stochastic gradient systems in Riemannian manifolds and prove that, under certain assumptions, such distributions are symmetric. These results are extended to countable products of finite dimensional manifolds and applied to Gibbs distributions in the case where the single spin spaces are Riemannian manifolds. In particular, we obtain a new result concerning the question whether all invariant measures are Gibbsian. Actually, we consider a more general object: weak elliptic equations for measures, which, on the one hand, yields the results obtained stronger than the above mentioned statements, and, on the other hand, enables us to give simpler proofs of more general than previously known facts. Applications to concrete models of lattice systems over d with not necessarily compact spin space are presented (also in the case d 3 under certain assumptions of decay of interaction).  相似文献   

16.
In this paper it is implemented how to make compatible the boundary conditions and the gauge fixing conditions for complex general relativity written in terms of Ashtekar variables using the approach of Ref. [1]. Moreover, it is found that at first order in the gauge parameters, the Hamiltonian action is (on shell) fully gauge-invariant under the gauge symmetry generated by the first class constraints in the case when spacetime has the topology % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWefv3ySLgznf% gDOfdaryqr1ngBPrginfgDObYtUvgaiuaacqWFZestcqWFaCFpcqGH% 9aqpcaWGsbGaey41aq7exLMBbXgBd9gzLbvyNv2CaeXbbjxAHXgiv5% wAJ9gzLbsttbacgaGaa43Odaaa!52EB!\[\mathcal{M} = R \times \Sigma \] = R × and has no boundary. Thus, the statement that the constraints linear in the momenta do not contribute to the boundary terms is right, but only in the case when has no boundary.  相似文献   

17.
A functional model of the cochlea is devised on the basis of the results from classical experiments. The basilar membrane filter is investigated in detail. Its phase is close to linear in the region around the peak of the amplification. On one side this has consequences for the time analysis and on the other side this has led to a prediction on phase perception for very simple combinations of tones, a prediction which is now confirmed by experiments. Equivariance under the dilation group permits one to describe the model by a wavelet transform [Daubechies, Ten Lectures on Wavelets (SIAM, Philadelphia, 1992)]. The wavelet is discussed in reference to the phase analysis of the basilar membrane filter.  相似文献   

18.
The 2H(d,p)3H and 2H(d,n)3He reactions have been indirectly studied by means of the Trojan Horse Method applied to the quasi-free 2H(3He, p3H)1H?2H(3He, n3He)1H reaction at 18?MeV of beam energy. This is the first experiment where the spectator (here 1H) has been detected in coincidence with the charged participant, avoiding the limitations of standard neutron detectors. The d ? d relative energy has been measured from 1.5?MeV down to 2?keV, at center of mass angles from 40° to 170°. Indirect angular distributions are compared with the direct behaviour in the overlapping regions.  相似文献   

19.
The classical matter fields are sections of a vector bundle E with base manifold M, and the space L 2(E) of square integrable matter fields w.r.t. a locally Lebesgue measure on M, has an important module action of Cb(M){C_b^\infty(M)} on it. This module action defines restriction maps and encodes the local structure of the classical fields. For the quantum context, we show that this module action defines an automorphism group on the algebra of the canonical anticommutation relations, CAR(L 2(E)), with which we can perform the analogous localization. That is, the net structure of the CAR(L 2(E)) w.r.t. appropriate subsets of M can be obtained simply from the invariance algebras of appropriate subgroups. We also identify the quantum analogues of restriction maps, and as a corollary, we prove a well–known “folk theorem,” that the CAR(L 2(E)) contains only trivial gauge invariant observables w.r.t. a local gauge group acting on E.  相似文献   

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