345 research outputs found
Quantum Simulations of Relativistic Quantum Physics in Circuit QED
We present a scheme for simulating relativistic quantum physics in circuit
quantum electrodynamics. By using three classical microwave drives, we show
that a superconducting qubit strongly-coupled to a resonator field mode can be
used to simulate the dynamics of the Dirac equation and Klein paradox in all
regimes. Using the same setup we also propose the implementation of the
Foldy-Wouthuysen canonical transformation, after which the time derivative of
the position operator becomes a constant of the motion.Comment: 13 pages, 3 figure
Quantum Simulation of Dissipative Processes without Reservoir Engineering
We present a quantum algorithm to simulate general finite dimensional
Lindblad master equations without the requirement of engineering the
system-environment interactions. The proposed method is able to simulate both
Markovian and non-Markovian quantum dynamics. It consists in the quantum
computation of the dissipative corrections to the unitary evolution of the
system of interest, via the reconstruction of the response functions associated
with the Lindblad operators. Our approach is equally applicable to dynamics
generated by effectively non-Hermitian Hamiltonians. We confirm the quality of
our method providing specific error bounds that quantify itss accuracy.Comment: 7 pages + Supplemental Material (6 pages
Measuring Entanglement in a Photonic Embedding Quantum Simulator
Measuring entanglement is a demanding task that usually requires full
tomography of a quantum system, involving a number of observables that grows
exponentially with the number of parties. Recently, it was suggested that
adding a single ancillary qubit would allow for the efficient measurement of
concurrence, and indeed any entanglement monotone associated to antilinear
operations. Here, we report on the experimental implementation of such a
device---an embedding quantum simulator---in photonics, encoding the entangling
dynamics of a bipartite system into a tripartite one. We show that bipartite
concurrence can be efficiently extracted from the measurement of merely two
observables, instead of fifteen, without full tomographic information.Comment: Updated versio
Critical parametric quantum sensing
Critical quantum systems are a promising resource for quantum metrology
applications, due to the diverging susceptibility developed in proximity of
phase transitions. Here, we assess the metrological power of parametric Kerr
resonators undergoing driven-dissipative phase transitions. We fully
characterize the quantum Fisher information for frequency estimation, and the
Helstrom bound for frequency discrimination. By going beyond the asymptotic
regime, we show that the Heisenberg precision can be achieved with
experimentally reachable parameters. We design protocols that exploit the
critical behavior of nonlinear resonators to enhance the precision of quantum
magnetometers and the fidelity of superconducting qubit readout.Comment: 6 pages + Supplemental Material, 4 figure
Comparison of the compositional, microbiological, biochemical, and volatile profile characteristics of nine Italian ewes' milk cheeses.
Abstract Nine Italian ewes' milk cheeses were compared for compositional, microbiological, biochemical, and volatile profile characteristics. Mean values for the gross composition were rather similar among cheeses. The lowest pH values were found for cheeses that used primary starters. At the end of ripening, cheeses made from raw milk contained >6.0 log 10 cfu/g of nonstarter lactic acid bacteria. Several species of lactobacilli were identified, but Lactobacillus plantarum and Lactobacillus paracasei were dominant. Random amplified polymorphic DNA-PCR analysis showed the biodiversity among the strains, and in several cases a relationship with the cheese of provenance. Cheeses differed mainly for secondary proteolysis, as shown by the principal component analysis applied to reversed-phase fast protein liquid chromatography data of the pH 4.6-soluble fractions and by determination of the free AA. A total of 113volatile components were identified in the Italian Pecorino cheeses by solid-phase microextraction coupled with gas chromatography–mass spectrometry analysis. The volatile profiles of the 9 cheeses differed significantly. Quantitatively, alcohols were the most abundant chemical class for some cheeses, whereas ketones were the most abundant for other cheeses. Esters and carboxylic acids were largely found. Specific volatile components seemed to distinguish specific cheeses
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