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Secret sharing plays a fundamental role in both secure multi-party computation and modern cryptography. We present a new quantum secret sharing scheme based on quantum Fourier transform. This scheme enjoys the property that each share of a secret is disguised with true randomness, rather than classical pseudorandomness. Moreover, under the only assumption that a top priority for all participants (secret sharers and recovers) is to obtain the right result, our scheme is able to achieve provable security against a computationally unbounded attacker.

Secure scalar product serves as an important primitive for secure multi-party computation and has a wide application in different areas, such as statistical analysis, data mining, computational geometry, etc. How to collaboratively compute the correct scalar product result without leaking any participantsʼ private information becomes the primary principle of designing secure scalar product schemes. In this Letter, we present a secure two-party quantum scalar product scheme via quantum entanglement and quantum measurement with the help of a non-colluding third party (TP). Furthermore, the scheme is proven to be secure under various kinds of outside attacks and participant attacks.

We investigate the quantum sealed-bid auction protocol proposed by Zhao et al. (Opt Commun 283:1394, 2010). It uses M groups n-particle GHZ states to represent bids and a post-confirmation mechanism to guarantee the honesty of the quantum sealed-bid auction. However, in our opinion the protocol still does not complete the task of a sealed-bid auction fairly. It is shown that a large group of dishonest bidders can collude to obtain all the other one's secret bids before the opening phase of the auction with a probability polynomially close to one. Moreover, a simple feasible improvement of the protocol is proposed.

In this paper we propose a quantum group blind signature scheme designed for distributed e-voting system. Our scheme combines the properties of group signature and blind signature to provide anonymity of voters in an e-voting system. The unconditional security of our scheme is ensured by quantum mechanics. Without employing entanglement, the proposed scheme is easier to be realized comparing with other quantum signature schemes.

(Pt/Co)n/FeMn multilayers with perpendicular anisotropy (PA) were prepared by magnetron sputtering with Pt as the buffer layer and the capping layer. The dependence of perpendicular exchange bias (PEB), Hex, on the thickness of the FeMn antiferromagnet (AFM) layer is similar to that of in-plane exchange bias. The value of Hex for the (Pt/Co)3/FeMn multilayer reaches 22.3 kA/m. A thin Pt spacer was inserted between the Co/FeMn interface to enhance PEB. The PEB reaches the largest at 39.8 kA/m when the thickness of the Pt spacer is 0.4 nm.

The effects of Fe doping on the magnetic, transport, and magnetoresistance properties are studied for La0.7Sr0.3Mn1−yFeyO3 (y=0–0.18) and La1−xSrxMn0.88Fe0.12O3 (x=0.1–0.50). For increasing y, a peak in the thermal dependence of the resistivity appears and develops at the temperature TPl lower than TC, while the another peak near TC becomes smaller and then disappears. At 78 K the La1−xSrxMn0.88Fe0.12O3 oxides are insulators for x 0.5 and only the lower-temperature metal–insulator transition peak appears for 0.25

The CoFeB/Ni multilayers with Pt underlayer are prepared by magnetron sputtering technique and the perpendicular magnetic anisotropy (PMA) of each of the samples is studied by anomalous Hall effect (AHE) method. The PMA of CoFeB/Ni multilayer is dependent on the thickness of Pt, Co, CoFeB and the number of CoFeB/Ni bilayers strongly. It is found that the sample structured as Pt(4)/[CoFeB(tCoFeB)/Ni(0.3)]2/Pt(1.0) has a good PMA when the CoFeB thickness is 0.4 nm for the interface anisotropy dominated in the multilayer. So the CoFeB thickness is fixed at 0.4 nm. The effect of Ni thickness on multilayer PMA is also studied. The PMA of the sample is kept relatively well and the Hall resistance (RHall) decreases as the Ni thickness increases. Meanwhile the coercivity (HC) fluctuates in a small range. When the Ni thickness is 0.3 nm, the remanence squareness of the sample is very good and the Hall effect is strongest. The influence of period number n on the sample PMA is significant for it changes the interface of the sample. When n is 3, the sample has a very good remanence squareness, for the interface effect is obvious and the magnetization reversal process is consistent. The Pt underlayer shows a great effect on the PMA performance of the sample, for it can change the (111) texture of the multilayer. The results show that when the Pt thickness is 4 nm, the remanence squareness is good and the sample has a suitable HC. So the optimum CoFeB/Ni multilayer with an excellent performance of PMA is structured as Pt(4)/[CoFeB(0.4)/Ni(0.3)]3/Pt(1.0). Its anisotropy constant Keff is 2.2106 erg/cm3 (1 erg/cm3=10-1 J/m3) which indicates that the sample has an excellent PMA and its interface anisotropy is the main reason for making the Keff have a larger value. The magnetic layer thickness of the optimum sample is 2.1 nm and the total thickness of it is less than 8 nm. The integration with device can be studied further. Furthermore, HC of the CoFeB/Ni multilayer is relatively small and can be increased by inserting the oxidation layer or other ways.

Co/Ni multilayers with Pt underlayers have been prepared by magnetron sputtering technique, and their perpendicular magnetic anisotropy (PMA) was studied by the anomalous Hall effect (AHE). The PMA of the samples can be studied by the intensity of Hall signal (RHall), remanence ratio (Mr/Ms), coercivity (HC) and the squarefless of the samples in the Hall hysteresis loops. A clear PMA is observed in the as-deposited amorphous Co/Ni multilayers. The PMA of Co/Ni multilayers is strongly dependent on the thicknesses of Pt, Co, and Ni, and the number of Co/Ni bilayers. After testing, the thicknesses of Pt, Co, and Ni, and the periodic number (n) of Co/Ni bilayers are determined to be 2 nm, 0.2 nm, 0.4 nm and 1 respectively. The optimum Co/Ni multilayer with excellent performance of PMA has a structureflexpressed as Pt(2)/Co(0.2)/Ni(0.4)/Co(0.2)/Pt(2). The hysteresis loop of the sample with the field applied in plane is tested, showing the characteristics of hard axis typically. PMA can be measured by the anisotropy constant Keff which is determined by the competition of the interface anisotropy to the volume anisotropy. If the interface anisotropy is dominant, the sample will have PMA. The anisotropy constant Keff of Pt(2)/Co(0.2)/Ni(0.4)/Co(0.2)/Pt(2) is 3.6×105 J/m3, illustrating that it has an excellent PMA, and the interface anisotropy of Co/Ni is the main factor that makes Keff a larger value. Since the thickness of magnetic layer in the optimum sample is only 0.8 nm and the total thickness of it less than 5 nm, the integration of the device can be studied further. Furthermore, the coercivity of an optimum Co/Ni multilayered sample is relatively small and can be increased by inserting an oxidation layer or by other ways.

We investigate the fair quantum blind signature scheme proposed by Wang and Wen [Wang T Y and Wen Q Y 2010 Chin. Phys. B 19 060307], which uses the fundamental properties of quantum mechanics and the availability of a trusted arbitrator. However, in this paper, we find that the protocol cannot satisfy the property of non-forgeability even under the condition that the trusted arbitrator is totally credible. Moreover, a simple feasible suggestion for improving the protocol is proposed.

FePt/Au mutilayers were deposited on 100℃ MgO（001） single crystal substrate by magnetron sputtering. The influence of the FePt/Au multilayer structure on the ordering temperature, coercivity （ＨC）, perpendicular magnetic anisotropy （PMA）, FePt grain size and interparticle exchange coupling （IEC） of films were studied. Results show that the film possesses high ＨC, excellent PMA, small grain size and weak interparticle exchange coupling after annealing. The results of HRTEM reveal that Au can relieve mismatch between MgO and FePt lattices, leading to excellent PMA. Moreover, the FePt/Au interface energy, the stress energy due to the mismatch between FePt and Au lattices and the diffusion of Au atoms promote the ordering of FePt film. This leads to the decrease of ordering temperature and considerable increase of ＨC. Au atoms partly diffuse to the boundaries of FePt phase and function as grain finer and particle isolator, which decrease the FePt grain size and IEC.

［FePt/BN］n multilayers were prepared on MgO (100) single crystal substrates at 250℃ with magnetron sputtering. The perpendicular texture of L10-FePt/BN particle films was formed after vacuum annealing. The results of X-ray diffraction and magnetic tests show that the ［FePt(2nm)/BN(0.5nm)］10 and ［FePt(1nm)/BN(0.25nm)］20 multilayers have excellent (001) texture when the films were sputtered on substrates at 250℃ after annealed at 700℃ for 1h. The mean size of L10-FePt particles is roughly 15—20nm and its perpendicular coercive force reaches 522 kA/m. Moreover, the Mr/Ms and switching filed distribution S* reach 0.99 and 0.94, respectively. This particle film is a candidate for future perpendicular magnetic recording media with ultrahigh density.

In this paper, the FePt films with Bi underlayer were prepared by dc magnetron sputtering on glass substrates. The L10-FePt films were obtained after the deposited samples were subjected to vacuum annealing at various temperatures. The effect of a Bi underlayer on the ordering temperature and magnetic properties of FePt films was studied. Experimental results show that the FePt film can realize the low-temperature ordering at 350℃ after introduction of a Bi underlayer. Moreover, the Bi underlayer can also obviously enhance the coercivity Hc of the film and enlarge the concentration range of FePt films with high Hc. We studied the distribution of Bi atoms by X-ray photoelectron spectroscopy and the change of crystal structure of FePt films by X-ray diffraction. The cause of the above observatious is associated with enhanced ordering degree of FePt films by the Bi diffusion during annealing process.

(FexPt1-x)100-yCuy(x=0.46—0.56,y=0,0.04,0.12) thin films with a fixed thickness of 50nm have been prepared by magnetron sputtering. The atomic ratio of Fe to Pt atoms was accurately controlled by DC co-sputtering. The ordering parameter of the L10 phase is not enhanced for the films with x>0.52. On the contrary, the ordering process is improved by the addition of Cu for the Pt-rich or stoichiometric thin films. In order to get the ordering of FePt films at a low annealing temperature, the lower the Fe content, the more addition of Cu is needed. It is found that the L10 phase can be obtained after annealing at 350℃ for 20 min only for films with the ratio of the (FeCu)/Pt in the range of 1.1—1.2.

The ［Co85 85 Cr15 15 /Pt］20 20 multilayers w ith Pt underlayers were prepared by magnetron sputtering and the effects of sputtering Ar gas pressure on m icrostructure and magnetic properties of ［Co85 85 Cr15 15 /Pt］20 20 mul tilayers were studied. The results show that sputtering Ar gas pressure has a gr eat effect on the microstructure, perpendicular magnetic anisotropy and the coer civity of ［Co85 85 Cr15 15 /Pt］20 20 mul tilayers. For all samples, we have the effective magnetic anisotropy constant K eff eff ＞0, and all s amples showed perpendicular magnetic anisotropy. With increasing sputtering Ar g as pressure, the perpendicular and in-plane coercivity of the samples increase, but the effective magnetic anisotropy constant decreases. The coercivity of Pt( 20nm)/［(Co85 85 Cr15 15 (05nm)/Pt(15nm)］20 20 multilayers spu tter-depositied at 16Pa Ar gas pressures is increased to 130kA/m. The Pt( 20nm)/［(Co85 85 Cr15 15 (05nm)/Pt(15nm)］ 20 20 multilayers display perpendicular magnetic anisotropy and can be used as perpendicular magn etic recording media. The images of atomic force microscopy show that both avera ge grain size and the surface roughness increase with increasing sputtering Ar p ressure, which leads to the enhancement of perpendicular coercivity and the decr ease of effective magnetic anisotropy constant.

Fe/Pt multilayers and FePt thin films were prepared by DC magnetron sputtering. The as-prepared samples were subjected to vacuum annealing at temperatures in t he range of 300—550℃. The multilayered structure is an effective approach fo r reducing the ordering temperature of FePt. The ordering parameter S is evaluated to be 06, and correspondingly the coercivity is evaluated to be 501kA/m in ［Fe(15nm)/Pt(15nm)］1313 multilayers annealed at 350℃ for 20min. Relatively low ordering temperature for the multilayer is due to the e xtra driving force of ordering process caused by the vanishing of the multilayer interface at annealing.

The Fe/Pt multilayers with Ag,Ti,Cu,Cr,Pt and Ta underlayers were prepared by DC magnetron sputtering on the heated glass substrates.After vacuum annealing at d ifferent temperatures, the FePt thin films with L1０ ordering phase ( L1０-FePt) were obtained. Results showed that the Ag and Ti underlaye r prompt the ordering of FePt thin films, and the ordering temperature of FePt- L1０ phase is reduced by at least 150℃. It is also worth noting tha t the annealing time is shorter and the magnetic performance is excellent. The m agnetic performance of samples with Ag underlayer is not sensitive to temperatur e at relative higher annealing temperature, whereas the coercivity of samples wi th Ti underlayer decreases obviously when the annealing temperature is higher th an 500℃. After annealing at 400℃ for 20 min, the in-plane coercivity of sample s with Ag and Ti underlayer can be as high as 597kA/m, and 654kA/m， respectivel y, and the ratio of remanent magnetization to saturation magnetization reaches 0 .81 and 0.94, respectively, implying the potential of the films as future magnet ic recording media of ultrahigh density.

［FePt 2 nm/Ag d nm］10 (d=0—11) multilayers were prepared on single crystal MgO(100) substrates kept at room temperature and 250 ℃ by means of magnetosputtering. L10-FePt/Ag granular films with perpendicular magn etic anis otropy and high coercivity have been obtained after vacuum annealing the multila yers deposited on substrates kept at 250 ℃ for 15 min. X-ray diffraction result s indicate that FePt particles have a strong ［001］ orientation. The size of Fe Pt particles decreases with the increase of the thickness of Ag layer. After vac uum annealing the ［FePt 2 nm/Ag 9 nm］10 films at 600 ℃ for 15 min, FePt /Ag granular films are obtained with only 8 nm of particle size and 692 kA/m of coercivity. Isothermal magnetization remanence and dc-demagnetization remanence measurements show that no magnetic exchange coupling between magnetic particles can be observed. Such a kind of films is suitable for future ultra-density perp endicular magnetic recording medium.