Pure Dephasing of Light-Matter Systems in the Ultrastrong and Deep-Strong Coupling Regimes.

Pure dephasing originates from the nondissipative information exchange between quantum systems and environments, and plays a key role in both spectroscopy and quantum information technology. Often pure dephasing constitutes the main mechanism of decay of quantum correlations. Here we investigate how pure dephasing of one of the components of a hybrid quantum system affects the dephasing rate of the system transitions. We find that, in turn, the interaction, in the case of a light-matter system, can significantly affect the form of the stochastic perturbation describing the dephasing of a subsystem, depending on the adopted gauge. Neglecting this issue can lead to wrong and unphysical results when the interaction becomes comparable to the bare resonance frequencies of subsystems, which correspond to the ultrastrong and deep-strong coupling regimes. We present results for two prototypical models of cavity quantun electrodynamics: the quantum Rabi and the Hopfield model.

Spontaneous Scattering of Raman Photons from Cavity-QED Systems in the Ultrastrong Coupling Regime.

We show that spontaneous Raman scattering of incident radiation can be observed in cavity-QED systems without external enhancement or coupling to any vibrational degree of freedom. Raman scattering processes can be evidenced as resonances in the emission spectrum, which become clearly visible as the cavity-QED system approaches the ultrastrong coupling regime. We provide a quantum mechanical description of the effect, and show that ultrastrong light-matter coupling is a necessary condition for the observation of Raman scattering. This effect, and its strong sensitivity to the system parameters, opens new avenues for the characterization of cavity QED setups and the generation of quantum states of light.

Interaction of Mechanical Oscillators Mediated by the Exchange of Virtual Photon Pairs.

Two close parallel mirrors attract due to a small force (Casimir effect) originating from the quantum vacuum fluctuations of the electromagnetic field. These vacuum fluctuations can also induce motional forces exerted upon one mirror when the other one moves. Here, we consider an optomechanical system consisting of two vibrating mirrors constituting an optical resonator. We find that motional forces can determine noticeable coupling rates between the two spatially separated vibrating mirrors. We show that, by tuning the two mechanical oscillators into resonance, energy is exchanged between them at the quantum level. This coherent motional coupling is enabled by the exchange of virtual photon pairs, originating from the dynamical Casimir effect. The process proposed here shows that the electromagnetic quantum vacuum is able to transfer mechanical energy somewhat like an ordinary fluid. We show that this system can also operate as a mechanical parametric down-converter even at very weak excitations. These results demonstrate that vacuum-induced motional forces open up new possibilities for the development of optomechanical quantum technologies.

One Photon Can Simultaneously Excite Two or More Atoms.

We consider two separate atoms interacting with a single-mode optical or microwave resonator. When the frequency of the resonator field is twice the atomic transition frequency, we show that there exists a resonant coupling between one photon and two atoms, via intermediate virtual states connected by counterrotating processes. If the resonator is prepared in its one-photon state, the photon can be jointly absorbed by the two atoms in their ground state which will both reach their excited state with a probability close to one. Like ordinary quantum Rabi oscillations, this process is coherent and reversible, so that two atoms in their excited state will undergo a downward transition jointly emitting a single cavity photon. This joint absorption and emission process can also occur with three atoms. The parameters used to investigate this process correspond to experimentally demonstrated values in circuit quantum electrodynamics systems.

The Effect of Fracture Patterns, Pinning Configuration, Surgeon Experience and Subspecialty on Short-Term Radiological Outcomes of Pediatric Supracondylar Humeral Fractures Treated in the Prone Position: A Case-Series.

BACKGROUND: The most common treatment modality for supracondylar humerus fractures (SCHFs) in children is closed reduction and percutaneous pinning (CRPP). Nonetheless, debate persists regarding the optimal technique used. Therefore, the purpose of our study was to investigate the impact of surgeon experience, surgeon subspecialty and pin configuration on short-term radiological outcomes following CRPP of displaced SCHFs. METHODS: Patients less than 14 years of age who underwent CRPP for displaced SCHFs in the prone position between January 2018 and December 2022 were analyzed. Patients were separated into subgroups based on fracture type (low vs. high sagittal), pin configuration (lateral, cross, other), number and configuration of K-wires and first operator surgical experience. The following outcome measurements were collected: postoperative Baumann angle (BA), Shaft-Condylar angle (SCA), surgical duration (SD), duration of radiation exposure (DRE) and number of clinical and radiological follow-ups (FU). RESULTS: A total of 44 patients with a mean age of 6 ± 2.5 years were included in the final analysis. The mean post-operative BA and SCA were 74.8° ± 4.9° and 37.7° ± 10.2°, respectively. No significant differences were found in the post-operative Baumann's angle or SCA among the subgroups. Regarding secondary outcomes, no differences were found among each subgroup regarding SD, DRE and FUs. CONCLUSION: Short-term radiological outcomes following the treatment of SCHFs treated in the prone position are not affected by fracture patterns and pinning configuration, regardless of the surgeon's years of experience or subspecialty.

A novel KCNA1 mutation associated with global delay and persistent cerebellar dysfunction.

Episodic Ataxia Type 1 is an autosomal dominant disorder characterized by episodes of ataxia and myokymia. It is associated with mutations in the KCNA1 voltage-gated potassium channel gene. In the present study, we describe a family with novel clinical features including persistent cerebellar dysfunction, cerebellar atrophy, and cognitive delay. All affected family members have myokymia and epilepsy, but only one individual has episodes of vertigo. Additional features include postural abnormalities, episodic stiffness and weakness. A novel KCNA1 mutation (c.1222G>T) which replaces a highly conserved valine with leucine at position 408 (p.Val408Leu) was identified in affected family members, and was found to augment the ability of the channel to inactivate. Together, our data suggests that KCNA1 mutations are associated with a broader clinical phenotype, which may include persistent cerebellar dysfunction and cognitive delay.

Common Coding Variants in SCN10A Are Associated With the Nav1.8 Late Current and Cardiac Conduction.

BACKGROUND: Genetic variants at the SCN5A/SCN10A locus are strongly associated with electrocardiographic PR and QRS intervals. While SCN5A is the canonical cardiac sodium channel gene, the role of SCN10A in cardiac conduction is less well characterized. METHODS: We sequenced the SCN10A locus in 3699 European-ancestry individuals to identify variants associated with cardiac conduction, and replicated our findings in 21,000 individuals of European ancestry. We examined association with expression in human atrial tissue. We explored the biophysical effect of variation on channel function using cellular electrophysiology. RESULTS: We identified 2 intronic single nucleotide polymorphisms in high linkage disequilibrium (r 2=0.86) with each other to be the strongest signals for PR (rs10428132, ß=-4.74, P=1.52×10-14) and QRS intervals (rs6599251, QRS ß=-0.73; P=1.2×10-4), respectively. Although these variants were not associated with SCN5A or SCN10A expression in human atrial tissue (n=490), they were in high linkage disequilibrium (r 2≥0.72) with a common SCN10A missense variant, rs6795970 (V1073A). In total, we identified 7 missense variants, 4 of which (I962V, P1045T, V1073A, and L1092P) were associated with cardiac conduction. These 4 missense variants cluster in the cytoplasmic linker of the second and third domains of the SCN10A protein and together form 6 common haplotypes. Using cellular electrophysiology, we found that haplotypes associated with shorter PR intervals had a significantly larger percentage of late current compared with wild-type (I962V+V1073A+L1092P, 20.2±3.3%, P=0.03, and I962V+V1073A, 22.4±0.8%, P=0.0004 versus wild-type 11.7±1.6%), and the haplotype associated with the longest PR interval had a significantly smaller late current percentage (P1045T, 6.4±1.2%, P=0.03). CONCLUSIONS: Our findings suggest an association between genetic variation in SCN10A, the late sodium current, and alterations in cardiac conduction.

Frequency conversion in ultrastrong cavity QED.

We propose a new method for frequency conversion of photons which is both versatile and deterministic. We show that a system with two resonators ultrastrongly coupled to a single qubit can be used to realise both single- and multiphoton frequency-conversion processes. The conversion can be exquisitely controlled by tuning the qubit frequency to bring the desired frequency-conversion transitions on or off resonance. Considering recent experimental advances in ultrastrong coupling for circuit QED and other systems, we believe that our scheme can be implemented using available technology.

Common and rare variants in SCN10A modulate the risk of atrial fibrillation.

BACKGROUND: Genome-wide association studies have shown that the common single nucleotide polymorphism rs6800541 located in SCN10A, encoding the voltage-gated Nav1.8 sodium channel, is associated with PR-interval prolongation and atrial fibrillation (AF). Single nucleotide polymorphism rs6800541 is in high linkage disequilibrium with the nonsynonymous variant in SCN10A, rs6795970 (V1073A, r(2)=0.933). We therefore sought to determine whether common and rare SCN10A variants are associated with early onset AF. METHODS AND RESULTS: SCN10A was sequenced in 225 AF patients in whom there was no evidence of other cardiovascular disease or dysfunction (lone AF). In an association study of the rs6795970 single nucleotide polymorphism variant, we included 515 AF patients and 2 control cohorts of 730 individuals free of AF and 6161 randomly sampled individuals. Functional characterization of SCN10A variants was performed by whole-cell patch-clamping. In the lone AF cohort, 9 rare missense variants and 1 splice site donor variant were detected. Interestingly, AF patients were found to have higher G allele frequency of rs6795970, which encodes the alanine variant at position 1073 (described from here on as A1073, odds ratio =1.35 [1.16-1.54]; P=2.3×10(-5)). Both of the common variants, A1073 and P1092, induced a gain-of-channel function, whereas the rare missense variants, V94G and R1588Q, resulted in a loss-of-channel function. CONCLUSIONS: The common variant A1073 is associated with increased susceptibility to AF. Both rare and common variants have effect on the function of the channel, indicating that these variants influence susceptibility to AF. Hence, our study suggests that SCN10A variations are involved in the genesis of AF.

Orthodontic therapy and third party in Europe.

This paper is an attempt to individuate some principles and guidelines apt to regulate the relationship between orthodontists and financing third parties, applicable to most western European Countries. The concepts of orthodontic treatment need, orthodontic treatment request and orthodontic screening are discussed, alongside with a short overview of some of the most common indexes to assess the severity of the malocclusion and/or the treatment priority. The screening method introduced by the Danish Ministry of Health is presented; its importance lies in the fact that for the first time a direct correlation between health risk and individual malocclusions is recognized and assessed. In the discussion, it is stressed how the screening system tightly depends on the chosen general model for orthodontic care. Different models of orthodontic care organization as presently used in many European countries are presented and shortly discussed; among these, the Norwegian model is described more in details, because of its simplicity. Eventually, some guidelines considered necessary in order to achieve satisfactory standards of quality and efficiency are presented and discussed.