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QUROPE - aggregated feeds in category PhysicsenarXiv.org: Quantum Physics: Continuous symmetries and approximate quantum error correction. (arXiv:1902.07714v1 [quant-ph])
http://arxiv.org/abs/1902.07714
<p>Quantum error correction and symmetry arise in many areas of physics,
including many-body systems, metrology in the presence of noise, fault-tolerant
computation, and holographic quantum gravity. Here we study the compatibility
of these two important principles. If a logical quantum system is encoded into
$n$ physical subsystems, we say that the code is covariant with respect to a
symmetry group $G$ if a $G$ transformation on the logical system can be
realized by performing transformations on the individual subsystems.<p><a href="http://arxiv.org/abs/1902.07714">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: Optimal Coherent Filtering for Single Noisy Photons. (arXiv:1902.07720v1 [quant-ph])
http://arxiv.org/abs/1902.07720
<p>We introduce a filter using a noise-free quantum buffer with large optical
bandwidth that can both filter temporal-spectral modes, as well as
inter-convert them and change their frequency. We show that such quantum
buffers optimally filter out temporal-spectral noise; producing identical
single-photons from many distinguishable noisy single-photon sources with the
minimum required reduction in brightness.<p><a href="http://arxiv.org/abs/1902.07720">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: Continuous groups of transversal gates for quantum error correcting codes from finite clock reference frames. (arXiv:1902.07725v1 [quant-ph])
http://arxiv.org/abs/1902.07725
<p>Following the recent introduction of the task of reference frame error
correction, we show how, by using reference frame alignment for clocks,
near-perfect codes with a continuous Abelian group of transversal logical gates
can be constructed. With this we further explore a way of circumventing the
no-go theorem of Eastin and Knill, which states that if local errors are
correctable, the group of transversal gates must be of finite order. We are
able to do this by introducing a small error on the decoding procedure that
decreases with the dimension of the frames used.<p><a href="http://arxiv.org/abs/1902.07725">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: Zeno Friction and Anti-friction from Quantum Collision Models. (arXiv:1902.07738v1 [quant-ph])
http://arxiv.org/abs/1902.07738
<p>We analyze the quantum mechanics of the friction experienced by a small
system as it moves non-destructively with velocity $v$ over a surface.
Specifically, we model the interactions between the system and the surface with
a \textit{collision model}. We show that, under weak assumptions, the magnitude
of the friction induced by this interaction decreases as $1/v$ for large
velocities. Specifically, we predict that this phenomenon occurs in the Zeno
regime, where each of the system's successive couplings to subsystems of the
surface is very brief.<p><a href="http://arxiv.org/abs/1902.07738">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: Reverse engineering pairwise entanglement. (arXiv:1902.07754v1 [quant-ph])
http://arxiv.org/abs/1902.07754
<p>Designing algorithms for medium and large scale quantum computers is not
easy. In previous work we have suggested, and developed, the idea of using
machine learning techniques to train a quantum system such that the desired
process is "learned," thus obviating the algorithm design difficulty. This
works quite well. But it is also of interest to explore what exactly these
learned "algorithms" are.<p><a href="http://arxiv.org/abs/1902.07754">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: A general wave-packet evolution method for studying coherence of matter-wave interferometers. (arXiv:1902.07759v1 [cond-mat.quant-gas])
http://arxiv.org/abs/1902.07759
<p>We present a general method for calculating wave-packet evolution in the
context of ultracold atoms in matter-wave interferometers. This method provides
an efficient tool for analyzing the performance of atomic interferometers based
on atom clouds initially prepared in a trap in a Bose-Einstein condensate (BEC)
state or in a thermal distribution.<p><a href="http://arxiv.org/abs/1902.07759">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: Integrable Floquet Hamiltonian for a Periodically Tilted 1D Gas. (arXiv:1902.07809v1 [cond-mat.stat-mech])
http://arxiv.org/abs/1902.07809
<p>An integrable model subjected to a periodic driving gives rise generally to a
non-integrable Floquet Hamiltonian. Here we show that the Floquet Hamiltonian
of the integrable Lieb--Liniger model in presence of a linear potential with a
periodic time--dependent strength is instead integrable and its quasi-energies
can be determined using the Bethe ansatz approach. We discuss various aspects
of the dynamics of the system at stroboscopic times and we also propose a
possible experimental realisation of the periodically driven tilting in terms
of a shaken rotated ring potential.
</p>Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: Life, death, new species and children from a "Quantum Game of Life". (arXiv:1902.07834v1 [quant-ph])
http://arxiv.org/abs/1902.07834
<p>The classical "game of life" (GOL) due to Conway is a famous mathematical
game constructed as a two-dimensional cellular automaton in which each cell is
either alive or dead. A set of evolutionary rules determines whether a cell
dies, survives or is born at each generation based on its local environment.
The game of life is interesting because complexity emerges from simple rules
and mimics real life in that a cell flourishes only if the environment is "just
right" producing a breadth of life-like behavior including multi-cellular
lifeforms.<p><a href="http://arxiv.org/abs/1902.07834">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: The semi-quantum game of life. (arXiv:1902.07835v1 [quant-ph])
http://arxiv.org/abs/1902.07835
<p>Conway's classic game of life is a two-dimensional cellular automaton in
which each cell, either alive or dead, evolves according to rules based on its
local environment. The semi-quantum game of life (SQGOL) is an adaptation in
which each cell is in a superposed state of both dead and alive and evolves
according to modified rules. Computer simulation of the SQGOL reveals
remarkable complexity and previously unseen game behaviors.<p><a href="http://arxiv.org/abs/1902.07835">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100arXiv.org: Quantum Physics: An empiric logic approach to Einstein's version of the double-slit experiment. (arXiv:1902.07841v1 [quant-ph])
http://arxiv.org/abs/1902.07841
<p>As per Einstein's design, particles are introduced into the double-slit
experiment through a small hole in a plate which can either move up and down
(and its momentum can be measured) or be stopped (and its position can be
measured).<p><a href="http://arxiv.org/abs/1902.07841">read more</a></p>
Fri, 22 Feb 2019 14:45:11 +0100