281 research outputs found
Quantum Discord for Investigating Quantum Correlations without Entanglement in Solids
Quantum systems unfold diversified correlations which have no classical
counterparts. These quantum correlations have various different facets. Quantum
entanglement, as the most well known measure of quantum correlations, plays
essential roles in quantum information processing. However, it has recently
been pointed out that quantum entanglement cannot describe all the
nonclassicality in the correlations. Thus the study of quantum correlations in
separable states attracts widely attentions. Herein, we experimentally
investigate the quantum correlations of separable thermal states in terms of
quantum discord. The sudden change of quantum discord is observed, which
captures ambiguously the critical point associated with the behavior of
Hamiltonian. Our results display the potential applications of quantum
correlations in studying the fundamental properties of quantum system, such as
quantum criticality of non-zero temperature.Comment: 4 pages, 4 figure
Coherence-protected Quantum Gate by Continuous Dynamical Decoupling in Diamond
To implement reliable quantum information processing, quantum gates have to
be protected together with the qubits from decoherence. Here we demonstrate
experimentally on nitrogen-vacancy system that by using continuous wave
dynamical decoupling method, not only the coherence time is prolonged by about
20 times, but also the quantum gates is protected for the duration of
controlling time. This protocol shares the merits of retaining the superiority
of prolonging the coherence time and at the same time easily combining with
quantum logic tasks. It is expected to be useful in task where duration of
quantum controlling exceeds far beyond the dephasing time.Comment: 5 pages, 4 figure
Achieving Adversarial Robustness via Sparsity
Network pruning has been known to produce compact models without much
accuracy degradation. However, how the pruning process affects a network's
robustness and the working mechanism behind remain unresolved. In this work, we
theoretically prove that the sparsity of network weights is closely associated
with model robustness. Through experiments on a variety of adversarial pruning
methods, we find that weights sparsity will not hurt but improve robustness,
where both weights inheritance from the lottery ticket and adversarial training
improve model robustness in network pruning. Based on these findings, we
propose a novel adversarial training method called inverse weights inheritance,
which imposes sparse weights distribution on a large network by inheriting
weights from a small network, thereby improving the robustness of the large
network
Multi-functional hybrid protonated titanate nanobelts with tunable wettability
We present the preparation of millimetre-sized liquid marbles with strong mechanical strength and good deformability using self-assembled fluoroalkylsilane functionalized titanate nanobelt powder. The strength and deformability of the marbles are adjustable by changing the intrinsic wetting state of the titanate nanoparticles. The excellent chemical stability of surface layer on the liquid marbles consisting of the titanate nanobelts provides the possibility for qualitative and quantitative chemical sensing under a wide range of pH values.Environment and Water Industry Programme Office (EWI) under the National Research Foundation of Singapore[MEWR651/06/160]; National Nature Science Foundation of China[20773100, 51072170, 20620130427]; National Basic Research Program of China (973 Program)[2007CB935603]; Technical Program of Fujian Province, China[2007H0031
Effects of different transcranial magnetic stimulations on neuropathic pain after spinal cord injury
IntroductionRepetitive transcranial magnetic stimulation (rTMS) is an effective non-invasive cortical stimulation technique in the treatment of neuropathic pain. As a new rTMS technique, intermittent theta burst stimulation (iTBS) is also effective at relieving pain. We aimed to establish the pain-relieving effectiveness of different modalities on neuropathic pain. The study was conducted in individuals with spinal cord injury (SCI) and different modalities of rTMS.MethodsThirty-seven individuals with SCI were randomly allocated to three groups, in which the âiTBSâ group received iTBS, the ârTMSâ group received 10 Hz rTMS, and the âiTBS + rTMSâ group received iTBS and 10 Hz rTMS successively of the primary motor cortex 5 days a week for 4 weeks, and they all underwent the full procedures. The primary outcome measure was change in the visual analog scale (VAS), and the secondary outcomes were measured using the Hamilton Rating Scale for Depression (HAM-D) and the Pittsburgh Sleep Quality Index (PSQI). All the outcomes were evaluated at 1 day before stimulation (baseline), 1 day after the first week of stimulation (S1), and 1 day after the last stimulation (S2).ResultsThe VAS scores showed significant pain improvement after 4 weeks of stimulation (pâ=â0.0396, pâ=â0.0396, and pâ=â0.0309, respectively) but not after 1 week of stimulation. HAM-D scores declined, but the decreases were not significant until 4 weeks later (pâ=â0.0444, pâ=â0.0315, and pâ=â0.0447, respectively). PSQI scores were also significantly decreased after 4 weeks of stimulation (pâ=â0.0446, pâ=â0.0244, and pâ=â0.0088, respectively). Comparing the three modalities, VAS, HAM-D, and PSQI scores at S1 showed no differences, and, at S2, VAS scores showed significant differences (pâ=â0.0120; multiple comparisons showed significant differences between iTBS and iTBS + rTMS, pâ=â0.0091), while the HAM-D and PSQI scores showed no differences.DiscussionThe primary and secondary outcomes all showed significant improvement, indicating that the three different modalities were all effective at relieving the pain. However, not all the three stimulations were of same effectiveness after treatment; there were statistical differences in the treatment of neuropathic pain between iTBS as a priming stimulus and as a single procedure
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