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QUROPE - aggregated feedsenarXiv.org: Quantum Physics: Low-cost limit of classical communication with restricted quantum measurements. (arXiv:1911.06335v1 [quant-ph])
http://arxiv.org/abs/1911.06335
<p>We consider a scenario when classical information is encoded in an ensemble
of quantum states that admit a power series expansion in a cost parameter and
with the vanishing cost converge to a single zero-cost state. We derive an
approximate expression for mutual information in the leading order of the cost
parameter. The general results are applied to selected problems in optical
communication, where coherent states of light are used as input symbols and the
cost is quantified as the average number of photons per symbol.<p><a href="http://arxiv.org/abs/1911.06335">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Channel Activation of CHSH Nonlocality. (arXiv:1911.06349v1 [quant-ph])
http://arxiv.org/abs/1911.06349
<p>Quantum channels that break CHSH nonlocality on all input states are known as
CHSH-breaking channels. In quantum networks, such channels are useless for
distributing correlations that can violate the CHSH Inequality. Motivated by
previous work on activation of nonlocality in quantum states, here we
demonstrate an analogous activation of CHSH-breaking channels. That is, we show
that certain pairs of CHSH-breaking channels are no longer CHSH-breaking when
used in combination.<p><a href="http://arxiv.org/abs/1911.06349">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Thermodynamic analysis of quantum error correcting engines. (arXiv:1911.06354v1 [quant-ph])
http://arxiv.org/abs/1911.06354
<p>Quantum error correcting codes can be cast in a way which is strikingly
similar to a quantum heat engine undergoing an Otto cycle. In this paper we
strengthen this connection further by carrying out a complete assessment of the
thermodynamic properties of 4-strokes operator-based error correcting codes.
This includes an expression for the entropy production in the cycle which, as
we show, contains clear contributions stemming from the different sources of
irreversibility.<p><a href="http://arxiv.org/abs/1911.06354">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Quantum Computing for Neutrino-nucleus Scattering. (arXiv:1911.06368v1 [quant-ph])
http://arxiv.org/abs/1911.06368
<p>Neutrino-nucleus cross section uncertainties are expected to be a dominant
systematic in future accelerator neutrino experiments. The cross sections are
determined by the linear response of the nucleus to the weak interactions of
the neutrino, and are dominated by energy and distance scales of the order of
the separation between nucleons in the nucleus. These response functions are
potentially an important early physics application of quantum computers. Here
we present an analysis of the resources required and their expected scaling for
scattering cross section calculations.<p><a href="http://arxiv.org/abs/1911.06368">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Quantum Electron Transport in Degenerate Donor-Acceptor Systems. (arXiv:1911.06370v1 [quant-ph])
http://arxiv.org/abs/1911.06370
<p>We develop a mathematically rigorous theory for the quantum transfer
processes in degenerate donor-acceptor dimers in contact with a thermal
environment. We calculate explicitly the transfer rates and the acceptor
population efficiency. The latter depends critically on the initial donor
state. We show that quantum coherence in the initial state enhances the
transfer process. If the electron is initially shared coherently by the donor
levels then the efficiency can reach values close to 100%, while an incoherent
initial donor state will significantly suppress the efficiency.<p><a href="http://arxiv.org/abs/1911.06370">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Efficient Implementation of a Quantum Algorithm in a Single Nitrogen Vacancy Center of Diamond. (arXiv:1911.06371v1 [quant-ph])
http://arxiv.org/abs/1911.06371
<p>Quantum computers have the potential to speed up certain problems that are
hard for classical computers. Hybrid systems, such as the nitrogen vacancy (NV)
center in diamond, are among the most promising systems to implement quantum
computing, provided the control of the different types of qubits can be
efficiently implemented. In the case of the NV center, the anisotropic
hyperfine interaction allows one to control the nuclear spins indirectly,
through gate operations targeting the electron spin, combined with free
precession.<p><a href="http://arxiv.org/abs/1911.06371">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: An Integrated Photonic Platform for Rare-Earth Ions in Thin Film Lithium Niobate. (arXiv:1911.06376v1 [physics.optics])
http://arxiv.org/abs/1911.06376
<p>Rare-earth ion ensembles doped in single crystals are a promising materials
system with widespread applications in optical signal processing, lasing, and
quantum information processing. Incorporating rare-earth ions into integrated
photonic devices could enable compact lasers and modulators, as well as on-chip
optical quantum memories for classical and quantum optical applications. To
this end, a thin film single crystalline wafer structure that is compatible
with planar fabrication of integrated photonic devices would be highly
desirable.<p><a href="http://arxiv.org/abs/1911.06376">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Cooling to absolute zero: The unattainability principle. (arXiv:1911.06377v1 [quant-ph])
http://arxiv.org/abs/1911.06377
<p>The unattainability principle (UP) is an operational formulation of the third
law of thermodynamics stating the impossibility to bring a system to its ground
state in finite time. In this work, several recent derivations of the UP are
presented, with a focus on the set of assumptions and allowed sets of
operations under which the UP can be formally derived. First, we discuss
derivations allowing for arbitrary unitary evolutions as the set of operations.
There the aim is to provide fundamental bounds on the minimal achievable
temperature, which are applicable with almost full generality.<p><a href="http://arxiv.org/abs/1911.06377">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Entanglement-assisted Quantum Codes from Cyclic Codes. (arXiv:1911.06384v1 [cs.IT])
http://arxiv.org/abs/1911.06384
<p>Entanglement-assisted quantum (QUENTA) codes are a subclass of quantum
error-correcting codes which use entanglement as a resource. These codes can
provide error correction capability higher than the codes derived from the
traditional stabilizer formalism. In this paper, it is shown a general method
to construct QUENTA codes from cyclic codes. Afterwards, the method is applied
to Reed-Solomon codes, BCH codes, and general cyclic codes. We use the
Euclidean and Hermitian construction of QUENTA codes.<p><a href="http://arxiv.org/abs/1911.06384">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100arXiv.org: Quantum Physics: Near source fluorescence spectroscopy for miniaturized thermal atomic beams. (arXiv:1911.06388v1 [physics.atom-ph])
http://arxiv.org/abs/1911.06388
<p>Miniature atomic beams can provide new functionalities for atom based sensing
instruments such as atomic clocks and interferometers. We recently demonstrated
a planar silicon device for generating well-collimated thermal atomic beams
[Nat Commun 10, 1831 (2019)]. Here, we present a near-source fluorescence
spectroscopy (NSFS) technique that can fully characterize such miniature beams
even when measured only a few millimeters from the nozzle exit.<p><a href="http://arxiv.org/abs/1911.06388">read more</a></p>
Mon, 18 Nov 2019 16:45:08 +0100