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The kinetic equation of nonlocal and non-instantaneous character unifies the

achievements of the transport in dense quantum gases with the Landau theory of

quasiclassical transport in Fermi systems. Large cancellations in the off-shell

motion appear which are hidden usually in non-Markovian behaviors. The

remaining corrections are expressed in terms of shifts in space and time that

characterize the non-locality of the scattering process. In this way quantum

This work deals with models described by a single real scalar field in

two-dimensional spacetime. The aim is to propose potentials that support

massless minima and investigate the presence of kinklike structures that

engender polynomial tails. The results unveil the presence of families of

asymmetric solutions with energy density and linear stability that behave

adequately, enhancing the importance of the analytical study. We stress that

the novel topological structures which we find in this work engender long range

We study the optomechanical behaviour of a driven Fabry-P\'erot cavity

containing two vibrating dielectric membranes. We characterize the cavity-mode

frequency shift as a function of the two-membrane positions, and report a $\sim

2.47$ gain in the optomechanical coupling strength of the membrane relative

motion with respect to the single membrane case. This is achieved when the two

membranes are properly positioned to form an inner cavity which is resonant

We present a novel continuous dynamical decoupling scheme for the

construction of a robust qubit in a three-level system. By means of a clock

transition adjustment, we first show how robustness to environmental noise is

achieved, while eliminating drive-noise, to first-order. We demonstrate this

scheme with the spin sub-levels of the NV-centre's electronic ground state. By

applying drive fields with moderate Rabi frequencies, the drive noise is

eliminated and an improvement of 2 orders of magnitude in the coherence time is

We rigorously investigate the quantum non-Markovian dissipative dynamics of a

system coupled to a harmonic oscillator bath by deriving hierarchical

Schr\"{o}dinger equations of motion (HSEOM) and studying their dynamics. The

HSEOM are the equations for wave functions derived on the basis of the

Feynman-Vernon influence functional formalism for the density operator,

$\langle q|\rho(t)|q' \rangle$, where $\langle q|$ and $|q' \rangle$ are the

left- and right-hand elements. The time evolution of $\langle q|$ is computed

In standard formulations of the uncertainty principle, two fundamental

features are typically cast as impossibility statements: two noncommuting

observables cannot in general both be sharply defined (for the same state), nor

can they be measured jointly. The pioneers of quantum mechanics were acutely

aware and puzzled by this fact, and it motivated Heisenberg to seek a

mitigation, which he formulated in his seminal paper of 1927. He provided

intuitive arguments to show that the values of, say, the position and momentum

The experimental interest and developments in quantum spin-1/2-chains has

increased uninterruptedly over the last decade. In many instances, the target

quantum simulation belongs to the broader class of non-interacting fermionic

models, constituting an important benchmark. In spite of this class being

analytically efficiently tractable, no direct certification tool has yet been

reported for it. In fact, in experiments, certification has almost exclusively

The question of how Bell nonlocality behaves in bipartite systems of higher

dimensions is addressed. By employing the probability of violation of local

realism under random measurements as the figure of merit, we investigate the

nonlocality of entangled qudits with dimensions ranging from $d=2$ to $d=7$. We

proceed in two complementary directions. First, we study the specific Bell

scenario defined by the Collins-Gisin-Linden-Massar-Popescu (CGLMP) inequality.

Globally-constrained classical fields provide a unexplored framework for

modeling quantum phenomena, including apparent particle-like behavior. By

allowing controllable constraints on unknown past fields, these models are

retrocausal but not retro-signaling, respecting the conventional block universe

viewpoint of classical spacetime. Several example models are developed that

resolve the most essential problems with using classical electromagnetic fields

The Kochen-Specker theorem is a basic and fundamental 50 year old

non-existence result affecting the foundations of quantum mechanix, strongly

implying the lack of any meaningful notion of "quantum realism", and typically

leading to discussions of "contextuality" in quantum physics. Original proofs

of the Kochen-Specker theorem proceeded via brute force counter-examples; often

quite complicated and subtle (albeit mathematically "elementary")

counter-examples. Only more recently have somewhat more "geometrical" proofs