Cryptanalysis and improvement of the quantum private comparison protocol based on Bell entangled states

Recently, Liu et al. [Commun. Theor. Phys. 57, 583, 2012] proposed a quantum private comparison protocol based on entanglement swapping of Bell states, which aims to securely compare the equality of two participants' information with the help of a semi-honest third party (TP). However, this study points out there is a fatal loophole in this protocol, i.e., TP can obtain all of the two participants secret inputs without being detected through making a specific Bell-basis measurement. To fix the problem, a simple solution, which uses one-time eavesdropper checking with decoy photons instead of twice eavesdropper checking with Bell states, is demonstrated. Compared with the original protocol, it also reduces the Bell states consumption and simplifies the steps in the protocol.Comment: 9 pages, 1 figur

Improved Deterministic N-To-One Joint Remote Preparation of an Arbitrary Qubit via EPR Pairs

Recently, Bich et al. (Int. J. Theor. Phys. 51: 2272, 2012) proposed two deterministic joint remote state preparation (JRSP) protocols of an arbitrary single-qubit state: one is for two preparers to remotely prepare for a receiver by using two Einstein-Podolsky-Rosen (ERP) pairs; the other is its generalized form in the case of arbitrary N>2 preparers via N ERP pairs. In this paper, Through reviewing and analyzing Bich et al.'s second protocols with N>2 preparers, we find that the success probability P_{suc}=1/4 < 1. In order to solve the problem, we firstly constructed two sets of projective measurement bases: the real-coefficient basis and the complex-coefficient one, and further proposed an improved deterministic N-to-one JRSP protocol for an arbitrary single-qubit state with unit success probability (i.e, P_{suc}=1). Morever, our protocol is also flexible and convenient, and it can be used in a practical network.Comment: 13 pages, 2 figures, two table

Effect of Respiration on the Characteristic Ratios of Oscillometric Pulse Amplitude Envelope in Blood Pressure Measurement

Systolic and diastolic blood pressures (BPs) are important physiological parameters for disease diagnosis. Systolic and diastolic characteristic ratios derived from oscillometric pulse waveform have been widely used to estimate automated non-invasive BPs in oscillometric BP measurement devices. The oscillometric pulse waveform is easily influenced by respiration, which may cause variability to the characteristic ratios and subsequently BP measurement. This study quantitatively investigated how respiration patterns (i.e., normal breathing and deep breathing) affect the systolic and diastolic characteristic ratios. The study was performed with clinical data collected from 39 healthy subjects, and each subject conducted BP measurements during normal and deep breathings. Analytical results showed that the systolic characteristic ratio increased significantly from 0.52 ± 0.13 under normal breathing to 0.58 ± 0.14under deep breathing (p < 0.05), and the diastolic characteristic ratio was not significantly affected from 0.75 ± 0.12 under normal breathing to 0.76 ± 0.13 under deep breathing (p = 0.48). In conclusion, deep breathing significantly affected the systolic characteristic ratio, suggesting that automated oscillometric BP device which is validated under resting condition should be strictly used for measurements under resting condition