Fast implementation of length-adaptive privacy amplification in quantum key distribution

Post-processing is indispensable in quantum key distribution （QKD）, which is aimed at sharing secret keys between two distant parties. It mainly consists of key reconciliation and privacy amplification, which is used for sharing the same keys and for distilling unconditional secret keys. In this paper, we focus on speeding up the privacy amplification process by choosing a simple multiplicative universal class of hash functions. By constructing an optimal multiplication algorithm based on four basic multiplication algorithms, we give a fast software implementation of length-adaptive privacy amplification. ＂Length-adaptive＂ indicates that the implementation of privacy amplification automatically adapts to different lengths of input blocks. When the lengths of the input blocks are 1 Mbit and 10 Mbit, the speed of privacy amplification can be as fast as 14.86 Mbps and 10.88 Mbps, respectively. Thus, it is practical for GHz or even higher repetition frequency QKD systems.

Hydrogen and Ozone SAW Based Gas Sensors with RF Magnetron Sputtered InO_x and Electron Beam Evaporated SiN_y

Layered Surface Acoustic Wave (SAW) devices with an InO_x/SiN_u/36°YX LiTaO_3 structure were investigated for sensing low concentrations of hydrogen (H_2) and ozone (O_3) at different operating temperatures.The sensor consists of a 1μm thick silicon nitride (SiN_y) intermediate layer deposited by electron beam evaporation on a 36°Y-cut X-propagating piezoelectric lithium tantalate (LiTaO_3) substrate and a 100 nm thin indium oxide (InO_x) sensing layer deposited by R.F.magnetron sputtering.The device fabrication is described and the performance of the sensor is analyzed in terms of response magnitude as a function of operating temperature.Large frequency shifts of 360 kHz for 600μg/g of H_2 and 92 kHz for 40 ng/g O_3 were recorded.In addition,the surface morphology of the deposited films were investigated by Atomic Force Microscopy (AFM) and the chemical composition by X-Ray Photoelectron Spectroscopy (XPS) to correlate gas-sensing behavior to structural characteristics of the thin film.

Exhaled volatile organic compounds for cholangiocarcinoma diagnosis

Objectives:The difficulties in the early detection consequent to the lack of sensitive biomarkers render patients with cholangiocarcinoma(CCA)to have poor outcomes.Recently,sensitive and specific volatile organic compounds(VOCs)were identified in several cancers.However,the VOC profiles in CCA are not well-studied.Thus,we investigated the VOC profiles in exhaled breath of CCA patients and controls.Methods:We prospectively collected exhaled breath samples from 30 consecutive patients newly diagnosed with CCA and 30 controls who did not have CCA(seven had benign biliary strictures and 23 had other medical conditions).Exhaled VOCs were identified using gas chromatography mass spectrometry Triple Quadrupoles system.Analysis of the significant differences in VOCs between cases and controls was conducted using supervised multivariate regression analysis.Further validation was performed for these VOCs in another cohort of 18 CCA patients and 22 controls.Results:Levels of six compounds were significantly different between CCA patients and controls,namely,acetone,isopropyl alcohol,dimethyl sulfide,1,4-pentadiene,allyl methyl sulfide,and N,N-dimethylacetamide.Acetone and dimethyl sulfide were independently associated with CCA as demonstrated in the multivariate analysis.Using the cut-off value of 8.59107 arbitrary unit(AU),acetone had a sensitivity and specificity of 82.1%and 75.8%,respectively,with an area under the receiving operator curve(AUROC)of 0.85 for the CCA diagnosis.Acetone level was also significantly different between cases and controls in the validation cohort.Using the same cut-off value,the sensitivity,specificity,and AUROC was 59.1%,66.7%,and 0.85,respectively.Conclusion:Breath analysis may potentially be useful for CCA diagnosis.A cohort of patients with earlystage CCA in further studies is needed to confirm the ability of exhaled VOCs for the early detection of CCA.

Multilevel photon communication on BPPM with convolutional coding

Multilevel photon combined with binary pulse position modulation(BPPM)(Manchester pulsed signals), is introduced in this letter. Initially, error probability derivation and explanation for four-level photon communications with that BPPM is presented. Next, the 2-level photon communications matching with BPPM is proposed. For performance comparison, it is done with that the conventional scheme by fxing the background noise and also increasing number of photon per slot. Successfully with applying convolutional coding for system improving, the proposed multilevel photon on BPPM with this coding scheme achieves higher gain. Finally, this work also benefts to improving for further performance when considering with multilevel error control coding as well.