1,036 research outputs found
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 (). It's observed that the IBM QX4 architecture yields better gate
fidelity compared to IBM QX2 in all cases except the case of
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
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
Benford's distribution in extrasolar world: Do the exoplanets follow Benford's distribution?
In many real life situations, it is observed that the first digits (i.e.,
) of a numerical data-set, which is expressed using decimal
system, do not follow a random distribution. Instead, smaller numbers are
favoured by nature in accordance with a logarithmic distribution law, which is
referred to as Benford's law. The existence and applicability of this empirical
law have been extensively studied by physicists, accountants, computer
scientists, mathematicians, statisticians, etc., and it has been observed that
a large number of data-sets related to diverse problems follow this
distribution. However, applicability of Benford's law has been hardly tested
for extrasolar objects. Motivated by this fact, this paper investigates the
existence of Benford's distribution in the extrasolar world using Kepler data
for exoplanets. The investigation has revealed the presence of Benford's
distribution in various physical properties of these exoplanets. Further,
Benford goodness parameters are computed to provide a quantitative measure of
coincidence of real data with the ideal values obtained from Benford's
distribution. The quantitative analysis and the plots have revealed that
several physical parameters associated with the exoplanets (e.g., mass, volume,
density, orbital semi-major axis, orbital period, and radial velocity) nicely
follow Benford's distribution, whereas some physical parameters (e.g., total
proper motion, stellar age and stellar distance) moderately follow the
distribution, and some others (e.g., longitude, radius, and effective
temperature) do not follow Benford's distribution. Further, some specific
comments have been made on the possible generalizations of the obtained result,
its potential applications in analyzing data-set of candidate exoplanets, and
how interested readers can perform similar investigations on other interesting
data-sets.Comment: 7 pages, 3 figures and one potrai
Design and experimental realization of an optimal scheme for teleportion of an -qubit quantum state
An explicit scheme (quantum circuit) is designed for the teleportation of an
-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
-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
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