Trapped ions are ideally suited for precision spectroscopy, as is evident
from the remarkably low systematic uncertainties of single-ion clocks. The
major weakness of these clocks is the long averaging time, necessitated by the
low signal of a single atom. An increased number of ions can overcome this
limitation and allow for the implementation of novel clock schemes. However,
this presents the challenge to maintain the excellent control over systematic
shifts of a single particle in spatially extended and strongly coupled

We consider the evolution of a quantum state of a Hamiltonian which is
parametrically perturbed via a term proportional to the adiabatic parameter
\lambda (t). Starting with the Pechukas-Yukawa mapping of the energy
eigenvalues evolution on a generalised Calogero-Sutherland model of 1D
classical gas, we consider the adiabatic approximation with two different
expansions of the quantum state in powers of d\lambda/dt and compare them with
a direct numerical simulation. We show that one of these expansions (Magnus

In this study we show a way of achieving the reverse evolution of
n-dimensional quantum walks by introducing interventions on the coin degree of
freedom during the forward progression of the coin-walker system. Only a single
intervention is required to reverse a quantum walker on a line to its initial
positon and the number of interventions increases with the dimensionality of
the walk. We present an analytical treatment to prove these results. This
reversion scheme can be used to generate periodic bounded quantum walks and to

The entropic uncertainty relations are a very active field of scientific
inquiry. Their applications include quantum cryptography and studies of quantum
phenomena such as correlations and non-locality. In this work we find
entanglement-dependent entropic uncertainty relations in terms of the Tsallis
entropies for states with a fixed amount of entanglement. Our main result is
stated as Theorem~\ref{th:bound}. Taking the special case of von Neumann
entropy and utilizing the concavity of conditional von Neumann entropies, we

It is argued that quantum theory is best understood as requiring an
ontological duality of res extensa and res potentia, where the latter is
understood per Heisenberg's original proposal, and the former is roughly
equivalent to Descartes' 'extended substance.' However, this is not a dualism
of mutually exclusive substances in the classical Cartesian sense, and
therefore does not inherit the infamous 'mind-body' problem. Rather, res
potentia and res extensa are proposed as mutually implicative ontological

We propose a reference-frame-independent measurement-device-independent
quantum key distribution with uncharacterized quantum bits. We show security of
the protocol. The protocol can also be useful for implementation with channel
that has very low bit error rate but suffers large uncontrolled unitary

We present a quantum algorithm for simulating the dynamics of Hamiltonians
that are not necessarily sparse. Our algorithm is based on the assumption that
the entries of the Hamiltonian are stored in a data structure that allows for
the efficient preparation of states that encode the rows of the Hamiltonian. We
use a linear combination of quantum walks to achieve a poly-logarithmic
dependence on the precision. The time complexity measured in terms of circuit

Many promising applications of single crystal diamond and its color centers
as sensor platform and in photonics require free-standing membranes with a
thickness ranging from several micrometers to the few 100 nm range. In this
work, we present an approach to conveniently fabricate such thin membranes with
up to about one millimeter in size. We use commercially available diamond
plates (thickness 50 $\mu$m) in an inductively coupled reactive ion etching

Inspired by the algorithm of Barnsley's chaos game, we construct an open
quantum system model based on the repeated interaction process. We shown that
the quantum dynamics of the appropriate fermionic/bosonic system (in
interaction with an environment) provides a physical model of the chaos game.
When considering fermionic operators, we follow the system's evolution by
focusing on its reduced density matrix. The system is shown to be in a Gaussian
state (at all time $t$) and the average number of particles is shown to obey

The near-critical unitary dynamics of quantum Ising spin chains in
transversal and longitudinal magnetic fields is studied using an artificial
neural network representation of the wave function. A focus is set on strong
spatial correlations which build up in the system following a quench into the
vicinity of the quantum critical point. We compare correlations observed
following reinforcement learning of the network states with analytical
solutions in integrable cases and tDMRG simulations, as well as with