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QUROPE - aggregated feeds in category JournalsenPRA: Quantum information: Tuning the coupling between superconducting resonators with collective qubits
http://link.aps.org/doi/10.1103/PhysRevA.98.042328
<p>Author(s): Qi-Ming Chen, Yu-xi Liu, Luyan Sun, and Re-Bing Wu</p><p>By coupling a collection of two-level artificial atoms simultaneously to two superconducting resonators, we propose a quantum switch that can tune the resonator-resonator coupling strength from <i>zero</i> to a large value proportional to the qubit number. This process is realized by preparing the qubits i...</p><br/><p>[Phys. Rev. A 98, 042328] Published Fri Oct 19, 2018</p>Fri, 19 Oct 2018 12:00:00 +0200arXiv.org: Quantum Physics: Effective multi-body SU($N$)-symmetric interactions of ultracold fermionic atoms on a 3-D lattice. (arXiv:1810.07182v1 [cond-mat.quant-gas])
http://arxiv.org/abs/1810.07182
<p>Rapid advancements in the experimental capabilities with ultracold
alkaline-earth-like atoms (AEAs) bring to a surprisingly near term the prospect
of performing quantum simulations of spin models and lattice field theories
exhibiting SU($N$) symmetry. Motivated in particular by recent experiments
preparing high density samples of strongly interacting ${}^{87}$Sr atoms in a
three-dimensional optical lattice, we develop a low-energy effective theory of
fermionic AEAs which exhibits emergent multi-body SU($N$)-symmetric
interactions, where $N$ is the number of atomic nuclear spin levels.<p><a href="http://arxiv.org/abs/1810.07182">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: Quasiparticle Origin of Dynamical Quantum Phase Transitions. (arXiv:1810.07187v1 [cond-mat.str-el])
http://arxiv.org/abs/1810.07187
<p>Considering nonintegrable quantum Ising chains with exponentially decaying
interactions, we present matrix product state results that establish a
connection between low-energy quasiparticle excitations and the kind of
nonanalyticities in the Loschmidt return rate. When local spin excitations are
energetically favorable to two-domain-wall excitations in the quench
Hamiltonian, anomalous cusps appear in the return rate regardless of initial
state, except in the nearest-neighbor limit.<p><a href="http://arxiv.org/abs/1810.07187">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: Spin-stress and spin-strain coupling in diamond-based hybrid spin oscillator systems. (arXiv:1810.07190v1 [cond-mat.mes-hall])
http://arxiv.org/abs/1810.07190
<p>Hybrid quantum systems, which combine quantum-mechanical systems with
macroscopic mechanical oscillators, have attracted increasing interest as they
are well suited as high-performance sensors or transducers in quantum
computers. A promising candidate is based on diamond cantilevers, whose motion
is coupled to embedded Nitrogen-Vacancy (NV) centers through crystal
deformation.<p><a href="http://arxiv.org/abs/1810.07190">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: Reinforcement Learning Decoders for Fault-Tolerant Quantum Computation. (arXiv:1810.07207v1 [quant-ph])
http://arxiv.org/abs/1810.07207
<p>Topological error correcting codes, and particularly the surface code,
currently provide the most feasible roadmap towards large-scale fault-tolerant
quantum computation. As such, obtaining fast and flexible decoding algorithms
for these codes, within the experimentally relevant context of faulty syndrome
measurements, is of critical importance.<p><a href="http://arxiv.org/abs/1810.07207">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: Active protection of a superconducting qubit with an interferometric Josephson isolator. (arXiv:1810.07234v1 [quant-ph])
http://arxiv.org/abs/1810.07234
<p>Nonreciprocal microwave devices play several critical roles in high-fidelity,
quantum-nondemolition (QND) measurement schemes. They separate input from
output, impose unidirectional routing of readout signals, and protect the
quantum systems from unwanted noise originated by the output chain. However,
state-of-the-art, cryogenic circulators and isolators are disadvantageous in
scalable superconducting quantum processors because they use magnetic materials
and strong magnetic fields.<p><a href="http://arxiv.org/abs/1810.07234">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: Transforming Some Stabilizer Codes into Hybrid Codes. (arXiv:1810.07239v1 [quant-ph])
http://arxiv.org/abs/1810.07239
<p>In this paper, we prove how to extend a subset of quantum stabilizer codes
into a qudit hybrid code storing $\log_2 p$ classical bits over a qudit space
with dimension $p$, with $p$ prime. Our proof also gives an explicit procedure
for finding the entire collection of stabilizer algebras for all of the
subcodes of the hybrid code.<p><a href="http://arxiv.org/abs/1810.07239">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: Quantization Viewed as Galois Extension. (arXiv:1810.07261v1 [quant-ph])
http://arxiv.org/abs/1810.07261
<p>Quantization is studied from a viewpoint of field extension. If the dynamical
fields and their action have a periodicity, the space of wave functions should
be algebraically extended `a la Galois, so that it may be consistent with the
periodicity. This was pointed out by Y. Nambu three decades ago. Having chosen
quantum mechanics (one dimensional field theory), this paper shows that a
different Galois extension gives a different quantization scheme. A new scheme
of quantization appears when the invariance under Galois group is imposed as a
physical state condition.<p><a href="http://arxiv.org/abs/1810.07261">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: A many-body index for quantum charge transport. (arXiv:1810.07351v1 [math-ph])
http://arxiv.org/abs/1810.07351
<p>We propose an index for gapped quantum lattice systems that conserve a
$\mathrm{U}(1)$-charge. This index takes integer values and it is therefore
stable under perturbations.<p><a href="http://arxiv.org/abs/1810.07351">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200arXiv.org: Quantum Physics: Entanglement Harvesting with Moving Mirrors in $(1+1)$ Dimensions. (arXiv:1810.07359v1 [quant-ph])
http://arxiv.org/abs/1810.07359
<p>We study the phenomenon of entanglement extraction from the vacuum of a
massless scalar field in $(1+1)$ dimensional spacetime in presence of a moving
Dirichlet boundary condition, i.e. mirror spacetime, using two inertial
Unruh-DeWitt detectors. We consider a variety of non-trivial trajectories for
these accelerating mirrors and find (1) an entanglement inhibition phenomenon
similar to that recently seen for black holes, providing another connection
between Hawking radiation and the dynamical Casimir effect, as well as (2)
trajectory-independent entanglement enhancement in some regimes.<p><a href="http://arxiv.org/abs/1810.07359">read more</a></p>
Thu, 18 Oct 2018 23:45:06 +0200