Comment on "Quantum Teleportation of Eight-Qubit State via Six-Qubit Cluster State"

Recently, Zhao et al., (Int. J. Theor. Phys. 57, 516-522 (2018)) have proposed a scheme for quantum teleportation of an eight-qubit quantum state using a six qubit cluster state. In this comment, it's shown that the quantum resource (multi-partite entangled state used as the quantum channel) used by Zhao et al., is excessively high and the task can be performed using any two Bell states as the task can be reduced to the teleportation of an arbitrary two qubit state. Further, a trivial conceptual mistake made by Zhao et al., in the description of the quantum channel has been pointed out. It's also mentioned that recently a trend of proposing teleportation schemes with excessively high quantum resources has been observed and the essence of this comment is applicable to all such proposals.Comment: It is shown that teleportation of multi qubit-states can be done using Bell state

Experimental realization of nondestructive discrimination of Bell states using a five-qubit quantum computer

A scheme for distributed quantum measurement that allows nondestructive or indirect Bell measurement was proposed by Gupta et al., (Int. J. Quant. Infor. \textbf{5} (2007) 627) and subsequently realized experimentally using an NMR-based three-qubit quantum computer by Samal et al., (J. Phys. B, \textbf{43} (2010) 095508). In the present work, a similar experiment is performed using the five-qubit super-conductivity-based quantum computer, which has been recently placed in cloud by IBM Corporation. The experiment confirmed that the Bell state can be constructed and measured in a nondestructive manner with a reasonably high fidelity. A comparison of the outcomes of this study and the results obtained earlier in the NMR-based experiment has also been performed. The study indicates that to make a scalable SQUID-based computer, errors by the gates (in the present technology) have to be reduced considerably.Comment: 7 figures,13 pages including 1 appendi

Complete characterization of the directly implementable quantum gates used in the IBM quantum processors

Quantum process tomography of each directly implementable quantum gate used in the IBM quantum processors is performed to compute gate error in order to check viability of complex quantum operations in the superconductivity-based quantum computers introduced by IBM and to compare the quality of these gates with the corresponding gates implemented using other technologies. Quantum process tomography (QPT) of C-NOT gates have been performed for three configurations available in IBM QX4 processor. For all the other allowed gates QPT have been performed for every allowed position (i.e., by placing the gates in different qubit lines) for IBM QX4 architecture, and thus, gate fidelities are obtained for both single-qubit and 2-qubit gates. Gate fidelities are observed to be lower than the corresponding values obtained in the other technologies, like NMR. Further, gate fidelities for all the single-qubit gates are obtained for IBM QX2 architecture by placing the gates in the third qubit line ($q[2]$). It's observed that the IBM QX4 architecture yields better gate fidelity compared to IBM QX2 in all cases except the case of $\operatorname{Y}$ gate as far as the gate fidelity corresponding to the third qubit line is concerned. In general, the analysis performed here leads to a conclusion that a considerable technological improvement would be inevitable to achieve the desired scalability required for the realization of complex quantum operations.Comment: Quantum Process tomography has been done for all the gates used in IBM QX2 and IBM QX

Teleportation of a qubit using entangled non-orthogonal states: A comparative study

The effect of non-orthogonality of an entangled non-orthogonal state based quantum channel is investigated in detail in the context of the teleportation of a qubit. Specifically, average fidelity, minimum fidelity and minimum assured fidelity (MASFI) are obtained for teleportation of a single qubit state using all the Bell type entangled non-orthogonal states known as quasi Bell states. Using Horodecki criterion, it is shown that the teleportation scheme obtained by replacing the quantum channel (Bell state) of the usual teleportation scheme by a quasi Bell state is optimal. Further, the performance of various quasi Bell states as teleportation channel is compared in an ideal situation (i.e., in the absence of noise) and under different noise models (e.g., amplitude and phase damping channels). It is observed that the best choice of the quasi Bell state depends on the amount non-orthogonality, both in noisy and noiseless case. A specific quasi Bell state, which was found to be maximally entangled in the ideal conditions, is shown to be less efficient as a teleportation channel compared to other quasi Bell states in particular cases when subjected to noisy channels. It has also been observed that usually the value of average fidelity falls with an increase in the number of qubits exposed to noisy channels (viz., Alice's, Bob's and to be teleported qubits), but the converse may be observed in some particular cases.Comment: 14 pages, 4 figure

Design and experimental realization of an optimal scheme for teleportion of an nn-qubit quantum state

An explicit scheme (quantum circuit) is designed for the teleportation of an $n$-qubit quantum state. It is established that the proposed scheme requires an optimal amount of quantum resources, whereas larger amount of quantum resources has been used in a large number of recently reported teleportation schemes for the quantum states which can be viewed as special cases of the general $n$-qubit state considered here. A trade off between our knowledge about the quantum state to be teleported and the amount of quantum resources required for the same is observed. A proof of principle experimental realization of the proposed scheme (for a 2-qubit state) is also performed using 5-qubit superconductivity-based IBM quantum computer. Experimental results show that the state has been teleported with high fidelity. Relevance of the proposed teleportation scheme has also been discussed in the context of controlled, bidirectional, and bidirectional-controlled state teleportation.Comment: 11 pages 4 figure

Accuracy of visual inspection with acetic acid for cervical pathology screening in low cost setup

Background: Cancer cervix, a preventable disease continues to be a cause of great concern to women’s health, being associated with agonizing morbidity and high mortality. Approximately 493,100 new cases and more than 273,000 deaths occur each year, among women worldwide.IN India the screening is largely based on pap smear, which is cumbersome procedure due to transportation of samples and follow up of patients are not usually feasible. Visual inspection with Acetic acid (VIA) is simple and easy to teach procedure. Follow-up of patients usually doesn’t require.Methods: This study includes a total of 1000 patients who attended OPD of gynecology. Each patient is subjected to VIA examination. Biopsy is taken from women with abnormal findings on VIA. The objectives of this study were to evaluate the sensitivity and specificity and positive predictive value of inspection of cervix with acetic acid in precancerous lesions of cervix.Results: When biopsy is taken as reference standard, VIA has sensitivity of 97.7%, specificity of 76.6%, PPV of 62.9% and NPV of 98.5%. The accuracy rate for VIA is 84.8%.Conclusions: VIA is highly sensitive for diagnosis and treatment of cervical pathology at the same sitting. It can be done cost effectively in low resource set up