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Hybrid interfaces between distinct quantum systems play a major role in the
implementation of quantum networks. Quantum states have to be stored in
memories to synchronize the photon arrival times for entanglement swapping by
projective measurements in quantum repeaters or for entanglement purification.
Here, we analyze the distortion of a single photon wave packet propagating
through a dispersive and absorptive medium with high spectral resolution.
Single photons are generated from a single In(Ga)As quantum dot with its

We consider a general model, describing a quantum impurity with degenerate
energy levels, interacting with a gas of itinerant electrons, derive the
scaling equation and analyse the connection between its explicit form and the
symmetry of interaction. On the basis of this analysis we write down explicitly
the scaling equation for the interaction acting on $su(3)$ Lie algebra and
having either $SU(2)\times U(1)$, or $SU(2)$ symmetry.

We design a series of quantum circuits that generate absolute maximally
entangled (AME) states to benchmark a quantum computer. A relation between
graph states and AME states can be exploited to optimize the structure of the
circuits and minimize their depth. Furthermore, we find that most of the
provided circuits obey majorization relations for every partition of the
system, and at every step of the quantum computation. The rational for our
approach is to benchmark quantum computers with maximal useful entanglement,

We look into the possibility of entanglement generation in a
parity(P)-time(T)-symmetric framework and demonstrate the non-violation of
non-signalling principle for the case of bipartite systems when at least one is
guided by PT-symmetric quantum mechanics. Our analysis is based on the use of
the CPT-inner product to construct the reduced density operators both before
and after the action of time evolution operator.

We theoretically investigate the possibility of performing high precision
estimation of an externally imposed acceleration using scalar bosons in a
single-well trap. We work at the level of a two-mode truncation, valid for weak
to intermediate two-body interaction couplings.The splitting process into two
modes is in our model entirely caused by the interaction between the
constituent bosons and is hence neither due to an externally imposed
double-well potential nor due to populating a spinor degree of freedom. The

We study the quasiparticle excitation and quench dynamics of the
one-dimensional transverse-field Ising model with power-law ($1/r^{\alpha}$)
interactions. We find that long-range interactions give rise to a confining
potential, which couples pairs of domain walls (kinks) into bound
quasiparticles, analogous to mesonic bound states in high-energy physics. We
show that these quasiparticles have signatures in the dynamics of order
parameters following a global quench and the Fourier spectrum of these order

Quantum memories for light are important components for future long distance
quantum networks. We present on-chip quantum storage of telecommunications band
light at the single photon level in an ensemble of erbium-167 ions in an
yttrium orthosilicate photonic crystal nanobeam resonator. Storage times of up
to 10 $\mu$s are demonstrated using an all-optical atomic frequency comb
protocol in a dilution refrigerator under a magnetic field of 380 mT. We show
this quantum storage platform to have high bandwidth, high fidelity, and

We realize the dynamical 1D spin-orbit-coupling (SOC) of a Bose-Einstein
condensate confined within an optical cavity. The SOC emerges through
spin-correlated momentum impulses delivered to the atoms via Raman transitions.
These are effected by classical pump fields acting in concert with the quantum
dynamical cavity field. Above a critical pump power, the Raman coupling emerges
as the atoms superradiantly populate the cavity mode with photons.
Concomitantly, these photons cause a back-action onto the atoms, forcing them

Topological pumping of edge states in finite crystals or quasicrystals with
non-trivial topological phases provides a powerful means for robust excitation
transfer. In most schemes of topological pumping, the edge states become
delocalized and immersed into the continuum during the adiabatic cycle,
requiring extremely slow evolution to avoid nonadiabatic effects. Here a scheme
of topological pumping based on adiabatic passage of edge and interface states
is proposed, which is more robust against nonadiabatic effects and avoids

In the original round-robin differential-phase-shift (RRDPS) quantum key
distribution and its improved method, the photon-number-resolving detectors are
must for the security. We present a RRDPS protocol with yes-no detectors only.
We get the upper bounds of mutual information of Alice and Eve, and Bob and
Eve, and the formula of key rate. Our main idea is to divide all counts into
two classes, the counts due to the odd number photons of incident detectors and

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