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

We propose a novel type of composite light-matter interferometer based on a
supersolid-like phase of a driven Bose-Einstein condensate coupled to a pair of
degenerate counterpropagating electromagnetic modes of an optical ring cavity.
The supersolid-like condensate under the influence of the gravity drags the
cavity optical potential with itself, thereby changing the relative phase of
the two {cavity electromagnetic fields}. Monitoring the phase evolution of the

Usually the influence of the quadratic Stark effect on an ion's trapping
potential is minuscule and only needs to be considered in atomic clock
experiments. In this work we excite a trapped ion to a Rydberg state with
polarizability $\sim$~eight orders of magnitude higher than a low-lying
electronic state; we find that the highly-polarizable ion experiences a vastly
different trapping potential owing to the Stark effect. We observe changes in
trap stiffness, equilibrium position and minimum potential, which can be tuned

Exceptional points, resulting from non-Hermitian degeneracies, have the
potential to enhance the capabilities of quantum sensing. Thus, finding
exceptional points in different quantum systems is vital for developing such
future sensing devices. Taking advantage of the enhanced light-matter
interactions in a confined volume on a metal nanoparticle surface, here we
theoretically demonstrate the existence of exceptional points in a system
consisting of quantum emitters coupled to a metal nanoparticle of subwavelength

The equivalence principle in combination with the special relativistic
equivalence between mass and energy, $E=mc^2$, is one of the cornerstones of
general relativity. However, for composite systems a long-standing result in
general relativity asserts that the passive gravitational mass is not simply
equal to the total energy. This seeming anomaly is supported by all explicit
derivations of the dynamics of bound systems, and is only avoided after
time-averaging. Here we rectify this misconception and derive from first

We review several no-go theorems attributed to Gisin and Hardy, Conway and
Kochen purporting the impossibility of Lorentz-invariant deterministic
hidden-variable model for explaining quantum nonlocality. Those theorems claim
that the only known solution to escape the conclusions is either to accept a
preferred reference frame or to abandon the hidden-variable program altogether.
Here we present a different alternative based on a foliation dependent
framework adapted to deterministic hidden variables. We analyse the impact of

Single quantum light-emitters are valuable resources for engineered quantum
systems. They can function as robust single-photon generators, allow optical
control of single spins, provide readout capabilities for atomic-scale sensors,
and provide interfaces between stationary and flying qubits. Environmental
factors can lead to single emitters exhibiting "blinking", whereby the
fluorescence level switches between on and off states. Detailed
characterisation of this blinking behaviour including determining the switching