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QUROPE - aggregated feeds in category PhysicsenarXiv.org: Quantum Physics: Circuit QED: single-step realization of a multiqubit controlled phase gate with one microwave photonic qubit simultaneously controlling $n-1$ microwave photonic qubits. (arXiv:1910.08542v1 [quant-ph])
http://arxiv.org/abs/1910.08542
<p>We present a novel method to realize a multi-target-qubit controlled phase
gate with one microwave photonic qubit simultaneously controlling $n-1$ target
microwave photonic qubits. This gate is implemented with $n$ microwave cavities
coupled to a superconducting flux qutrit. Each cavity hosts a microwave
photonic qubit, whose two logic states are represented by the vacuum state and
the single photon state of a single cavity mode, respectively. During the gate
operation, the qutrit remains in the ground state and thus decoherence from the
qutrit is greatly suppressed.<p><a href="http://arxiv.org/abs/1910.08542">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Dispersion Properties, Nonlinear Waves and Birefringence in Classical Nonlinear Electrodynamics. (arXiv:1910.08586v1 [physics.plasm-ph])
http://arxiv.org/abs/1910.08586
<p>Using the very basic physics principles, we have studied the implications of
quantum corrections to classical electrodynamics and the propagation of
electromagnetic waves and pulses.
</p><p><a href="http://arxiv.org/abs/1910.08586">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Solving the measurement problem within standard quantum theory. (arXiv:1910.08591v1 [quant-ph])
http://arxiv.org/abs/1910.08591
<p>A misunderstanding of entangled states has spawned decades of concern about
quantum measurements and a plethora of quantum interpretations. The
"measurement state" or "Schrodinger's cat state" of a superposed quantum system
and its detector is nonlocally entangled, suggesting that we turn to
nonlocality experiments for insight into measurements. By studying the full
range of superposition phases, these experiments show precisely what the
measurement state does and does not superpose.<p><a href="http://arxiv.org/abs/1910.08591">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Poisson stochastic master equation unravellings and the measurement problem: a quantum stochastic calculus perspective. (arXiv:1910.08649v1 [math-ph])
http://arxiv.org/abs/1910.08649
<p>The paper studies a class of quantum stochastic differential equations,
modeling an interaction of a system with its environment in the quantum noise
approximation. The space representing quantum noise is the symmetric Fock space
over L 2 (R + ). Using the isomorphism of this space with the space of
square-integrable functionals of the Poisson process, the equations can be
represented as classical stochastic differential equations, driven by Poisson
processes. This leads to a discontinuous dynamical state reduction which we
compare to the Ghirardi-Rimini-Weber model.<p><a href="http://arxiv.org/abs/1910.08649">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Light emission properties in a double quantum dot molecule immersed in a cavity: phonon-assisted tunneling. (arXiv:1910.08675v1 [quant-ph])
http://arxiv.org/abs/1910.08675
<p>Two main mechanisms dictate the tunneling process in a double quantum dot:
overlap of excited wave functions, effectively described as a tunneling rate,
and phonon-assisted tunneling. In this paper, we study different regimes of
tunneling that arise from the competition between these two mechanisms in a
double quantum dot molecule immersed in a unimodal optical cavity.<p><a href="http://arxiv.org/abs/1910.08675">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Electromagnetic vacuum fluctuations and topologically induced motion of a charged particle. (arXiv:1910.08694v1 [hep-th])
http://arxiv.org/abs/1910.08694
<p>We show that a nontrivial topologies of the spatial section of Minkowski
space-time allow for motion of a charged particle under quantum vacuum
fluctuation of the electromagnetic field. This is a potentially observable
effect of the quantum vacuum fluctuations of the electromagnetic field. We
derive mean squared velocity dispersion when the charged particle lies in
Minkowski space-time with compact spatial sections in one, two and/or three
directions.<p><a href="http://arxiv.org/abs/1910.08694">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Experimental quantification of coherence of a tunable quantum detector. (arXiv:1910.08779v1 [quant-ph])
http://arxiv.org/abs/1910.08779
<p>Quantum coherence is a fundamental resource that quantum technologies exploit
to achieve performance beyond that of classical devices. A necessary
prerequisite to achieve this advantage is the ability of measurement devices to
detect coherence from the measurement statistics. Based on a recently developed
resource theory of quantum operations, here we quantify experimentally the
ability of a typical quantum-optical detector, the weak-field homodyne
detector, to detect coherence.<p><a href="http://arxiv.org/abs/1910.08779">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: A simple approach to design quantum neural networks and its applications to kernel-learning methods. (arXiv:1910.08798v1 [quant-ph])
http://arxiv.org/abs/1910.08798
<p>We give an explicit simple method to build quantum neural networks (QNNs) to
solve classification problems. Besides the input (state preparation) and output
(amplitude estimation), it has one hidden layer which uses a tensor product of
$\log M$ two-dimensional rotations to introduce $\log M$ weights. Here $M$ is
the number of training samples. We also have an efficient method to prepare the
quantum states of the training samples. By the quantum-classical hybrid method
or the variational method, the training algorithm of this QNN is easy to
accomplish in a quantum computer.<p><a href="http://arxiv.org/abs/1910.08798">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Entangled Radiofrequency-Photonic Sensor Network. (arXiv:1910.08825v1 [quant-ph])
http://arxiv.org/abs/1910.08825
<p>Quantum metrology enables a measurement sensitivity below the standard
quantum limit (SQL), as demonstrated in the Laser Interferometer
Gravitational-wave Observatory (LIGO). As a unique quantum resource,
entanglement has been utilized to enhance the performance of, e.g., microscopy,
target detection, and phase estimation.<p><a href="http://arxiv.org/abs/1910.08825">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200arXiv.org: Quantum Physics: Reproducibility of high-performance quantum dot single-photon sources. (arXiv:1910.08863v1 [quant-ph])
http://arxiv.org/abs/1910.08863
<p>Single-photon sources based on semiconductor quantum dots have emerged as an
excellent platform for high efficiency quantum light generation. However,
scalability remains a challenge since quantum dots generally present
inhomogeneous characteristics. Here we benchmark the performance of fifteen
deterministically fabricated single-photon sources. They display an average
indistinguishability of 90.6 +/- 2.8 % with a single-photon purity of 95.4 +/-
1.5 % and high homogeneity in operation wavelength and temporal profile.<p><a href="http://arxiv.org/abs/1910.08863">read more</a></p>
Tue, 22 Oct 2019 04:22:41 +0200