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Time fractals and discrete scale invariance with trapped ions. (arXiv:1901.01661v2 [cond-mat.quant-gas] UPDATED)

We show that a one-dimensional chain of trapped ions can be engineered to
produce a quantum mechanical system with discrete scale invariance and
fractal-like time dependence. By discrete scale invariance we mean a system
that replicates itself under a rescaling of distance for some scale factor, and
a time fractal is a signal that is invariant under the rescaling of time. These
features are reminiscent of the Efimov effect, which has been predicted and
observed in bound states of three-body systems. We demonstrate that discrete

Band twisting and resilience to disorder in long-range topological superconductors. (arXiv:1903.06175v2 [cond-mat.supr-con] UPDATED)

Planar topological superconductors with power-law-decaying pairing display
different kinds of topological phase transitions where quasiparticles dubbed
nonlocal-massive Dirac fermions emerge. These exotic particles form through
long-range interactions between distant Majorana modes at the boundary of the
system. We show how these propagating-massive Dirac fermions neither mix with
bulk states nor Anderson-localize up to large amounts of static disorder

Transient synchronization in open quantum systems. (arXiv:1907.06886v1 [quant-ph])

The phenomenon of spontaneous synchronization arises in a broad range of
systems when the mutual interaction strength among components overcomes the
effect of detuning. Recently it has been studied also in the quantum regime
with a variety of approaches and in different dynamical contexts. We review
here transient synchronization arising during the relaxation of open quantum
systems, describing the common enabling mechanism in presence of either local
or global dissipation. We address both networks of harmonic oscillators and

An Introduction to the Holstein-Primakoff Transformation, with Applications in Magnetic Resonance. (arXiv:1907.07122v1 [cond-mat.other])

We have witnessed an impressive advancement in computer performance in the
last couple of decades. One would therefore expect a trickling down of the
benefits of this technological advancement to the borough of computational
simulation of multispin magnetic resonance spectra, but that has not been quite
the case. Though some significant progress has been made, chiefly by Kuprov and
collaborators, one cannot help but observe that there is still much to be done.

High-dimensional optical quantum logic in large operational spaces. (arXiv:1805.04410v3 [quant-ph] UPDATED)

The probabilistic nature of single-photon sources and photon-photon
interactions encourages encoding as much quantum information as possible in
every photon for the purpose of photonic quantum information processing. Here,
by encoding high-dimensional units of information (qudits) in time and
frequency degrees of freedom using on-chip sources, we report deterministic
two-qudit gates in a single photon with fidelities exceeding 0.90 in the
computational basis. Constructing a two-qudit modulo SUM gate, we generate and

Quantum thermal absorption machines: refrigerators, engines and clocks. (arXiv:1902.02672v3 [quant-ph] UPDATED)

The inexorable miniaturisation of technologies, the relentless drive to
improve efficiency and the enticing prospect of boosting performance through
quantum effects are all compelling reasons to investigate microscopic machines.
Thermal absorption machines are a particularly interesting class of device that
operate autonomously and use only heat flows to perform a useful task. In the
quantum regime, this provides a natural setting in which to quantify the
thermodynamic cost of various operations such as cooling, timekeeping or

Constructing continuous-variable spacetime quantum states from measurement correlations. (arXiv:1903.06312v2 [quant-ph] UPDATED)

Space-time is one of the most essential, yet most mysterious concepts in
physics. In quantum mechanics it is common to understand time as a marker of
instances of evolution and define states around all the space but at one time;
while in general relativity space-time is taken as a combinator, curved around
mass. Here we present a unified approach on both space and time in quantum
theory, and build quantum states across spacetime instead of only on spatial

Room temperature test of wave-function collapse using a levitated micro-oscillator. (arXiv:1907.06896v1 [quant-ph])

Wave-function collapse models predict a tiny break of energy conservation via
a weak spontaneous stochastic force acting on the system, and are attracting
experimental studies. Among various physical systems, mechanical based methods
provide a direct way to test such collapse induced force without any
assumptions on its spectral characteristics. Levitated micro-mechanical
oscillator has been recently proposed to be an ideal system. We demonstrated a
micro-oscillator generated by a micro-sphere diamagnetically levitated in a

High-Quality Protein Force Fields with Noisy Quantum Processors. (arXiv:1907.07128v1 [quant-ph])

A central problem in biophysics and computational drug design is accurate
modeling of biomolecules. The current molecular dynamics simulation methods can
answer how a molecule inhibits a cancerous cell signaling pathway, or the role
of protein misfolding in neurodegenerative diseases. However, the accuracy of
current force fields (interaction potential) limits the reliability of computer
simulations. Fundamentally a quantum chemistry problem, here we discuss
developing new force fields using scalable ab initio quantum chemistry

Quantum chaos in a Bose-Hubbard dimer with modulated tunnelling. (arXiv:1812.08456v2 [quant-ph] UPDATED)

In the large-$N$, classical limit, the Bose-Hubbard dimer undergoes a
transition to chaos when its tunnelling rate is modulated in time. We use exact
and approximate numerical simulations to determine the features of the
dynamically evolving state that are correlated with the presence of chaos in
the classical limit. We propose the statistical distance between initially
similar number distributions as a reliable measure to distinguish regular from
chaotic behaviour in the quantum dynamics. Besides being experimentally