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Dipole moments are a simple, global measure of the accuracy of the electron
density of a polar molecule. Dipole moments also affect the interactions of a
molecule with other molecules as well as electric fields. To directly assess
the accuracy of modern density functionals for calculating dipole moments, we
have developed a database of 200 benchmark dipole moments, using coupled
cluster theory through triple excitations, extrapolated to the complete basis

This paper reports on experiments realized on several IBM 5Q chips which show
evidence for the advantage of using error detection and fault-tolerant design
of quantum circuits. We show an average improvement of the task of sampling
from states that can be fault-tolerantly prepared in the $[[4,2,2]]$ code, when
using a fault-tolerant technique well suited to the layout of the chip. By
showing that fault-tolerant quantum computation is already within our reach,
the author hopes to encourage this approach.

Superconducting qubits are sensitive to a variety of loss mechanisms which
include dielectric loss from interfaces. The calculation of participation near
the key interfaces of planar designs can be accomplished through an analytical
description of the electric field density based on conformal mapping. In this
way, a two-dimensional approximation to coplanar waveguide and capacitor
designs produces values of the participation as a function of depth from the

We investigate the quantum Jensen divergences from the viewpoint of joint
convexity. It turns out that the set of the functions which generate jointly
convex quantum Jensen divergences on positive matrices coincides with the
Matrix Entropy Class which has been introduced by Chen and Tropp quite recently
in [Electron. J. Probab. 19 (2014), 1-30].

Known Majorana fermions models are considered as promising ones for the
purposes of quantum computing robust to decoherence. One of the most expecting
but unachieved goals is an effective control for braiding of Majoranas. Another
one is to describe ${\mathbb{Z}}_2$ topological semimetals, APRES spectra of
which testify on eight-fold degenerate chiral fermions with $SU(2)$ holonomy of
wave functions, whereas the last can not be reproduced within existing models.

Long spin relaxation times are a prerequisite for the use of spins in data
storage or nanospintronics technologies. An atomic-scale solid-state
realization of such a system is the spin of a transition metal atom adsorbed on
a suitable substrate. For the case of a metallic substrate, which enables
directly addressing the spin by conduction electrons, the experimentally
measured lifetimes reported to date are on the order of only hundreds of
femtoseconds. Here, we show that the spin states of iron atoms adsorbed

We investigate the reflectionlessness and invisibility properties in the
transverse electric (TE) mode solution of a linear homogeneous optical system
which comprises the $\mathcal{PT}$-symmetric structures covered by graphene
sheets. We derive analytic expressions, indicate roles of each parameter
governing optical system with graphene and justify that optimal conditions of
these parameters give rise to broadband and wide angle invisibility. Presence

We present a quantum repeater scheme that is based on individual Erbium and
Europium ions. Erbium ions are attractive because they emit photons at
telecommunication wavelength, while Europium ions offer exceptional spin
coherence for long-term storage. Entanglement between distant Erbium ions is
created by photon detection. The photon emission rate of each Erbium ion is
enhanced by a microcavity with high Purcell factor, as has recently been
demonstrated. Entanglement is then transferred to nearby Europium ions for

Encoding quantum information in the photon temporal mode (TM) offers a robust
platform for high-dimensional quantum protocols. The main practical challenge,
however, is to design a device that operates on single photons in specific TMs
and all coherent superpositions. The quantum pulse gate (QPG) is a
mode-selective sum-frequency generation designed for this task. Here, we
perform a full modal characterisation of a QPG using weak coherent states in
well-defined TMs. We reconstruct a full set of measurement operators, which

Ridge regression (RR), also called regularized linear regression, is an
important machine learning technique which introduces a regularization
hyperparameter to ordinary multiple linear regression for analyzing data
suffering from multicollinearity. Here we provide an efficient quantum
algorithm for RR. Specifically, by giving the technique of parallel Hamiltonian
simulation that can simulate a number of Hermitian matrices in parallel, we
develop a quantum version of $K$-fold cross-validation approach that can