Implementation of a Walsh-Hadamard Gate in a Superconducting Qutrit.

We have implemented a Walsh-Hadamard gate, which performs a quantum Fourier transform, in a superconducting qutrit. The qutrit is encoded in the lowest three energy levels of a capacitively shunted flux device, operated at the optimal flux-symmetry point. We use an efficient decomposition of the Walsh-Hadamard gate into two unitaries, generated by off-diagonal and diagonal Hamiltonians, respectively. The gate implementation utilizes simultaneous driving of all three transitions between the three pairs of energy levels of the qutrit, one of which is implemented with a two-photon process. The gate has a duration of 35 ns and an average fidelity over a representative set of states, including preparation and tomography errors, of 99.2%, characterized with quantum-state tomography. Compensation of ac-Stark and Bloch-Siegert shifts is essential for reaching high gate fidelities.

Publisher Correction: Probing the strongly driven spin-boson model in a superconducting quantum circuit.

The original PDF and HTML versions of this Article omitted the ORCID ID of the authors L. Magazzù and P. Forn-Díaz. (L. Magazzù: 0000-0002-4377-8387; P. Forn-Diaz: 0000-0003-4365-5157).The original PDF version of this Article contained errors in Eqs. (2), (6), (13), (14), (25), (26). These equations were missing all instances of 'Γ' and 'Δ', which are correctly displayed in the HTML version.Similarly, the inline equation in the third sentence of the caption of Fig. 2 was missing the left hand term 'Ω'.The original HTML version of this Article contained errors in Table 1. The correct version of the sixth row of the first column states 'Figure 2' instead of the original, incorrect 'Figure'. And the correction version of the ninth row of the first column states 'Figure 3' instead of the original, incorrect 'Figure'.This has been corrected in both the PDF and HTML versions of the Article.

Probing the strongly driven spin-boson model in a superconducting quantum circuit.

Quantum two-level systems interacting with the surroundings are ubiquitous in nature. The interaction suppresses quantum coherence and forces the system towards a steady state. Such dissipative processes are captured by the paradigmatic spin-boson model, describing a two-state particle, the "spin", interacting with an environment formed by harmonic oscillators. A fundamental question to date is to what extent intense coherent driving impacts a strongly dissipative system. Here we investigate experimentally and theoretically a superconducting qubit strongly coupled to an electromagnetic environment and subjected to a coherent drive. This setup realizes the driven Ohmic spin-boson model. We show that the drive reinforces environmental suppression of quantum coherence, and that a coherent-to-incoherent transition can be achieved by tuning the drive amplitude. An out-of-equilibrium detailed balance relation is demonstrated. These results advance fundamental understanding of open quantum systems and bear potential for the design of entangled light-matter states.

Biomarkers of low-grade inflammation in primary varicose veins of the lower limbs.

OBJECTIVE: To analyze serum biomarkers of CVD in selected patients with primary axial reflux of great saphenous vein in one or both lower limbs. PATIENTS AND METHODS: Ninety-six patients affected by uncomplicated varicose veins, were enrolled in the study. A unilateral, primary axial reflux in great saphenous veins was detected in 54 patients (U-CVD group) and a bilateral one in 42 (B-CVD group). Sixty-five age and sex-matched subjects without venous reflux were enrolled as controls. Mean venous pressure of both lower limbs at the distal great saphenous vein (mGSVP) and venous reflux were measured by continuous-wave Doppler ultrasound and echoduplex scanning, respectively. Reactive Oxygen Species (ROS), tissue Plasminogen Activator (t-PA) and its Inhibitor 1 (PAI-1) activities, Hematocrit (HTC), White Blood Cells (WBC), Neutrophyls (NEU), Platelets (PLT), Fibrinogen (FIB) and Blood Viscosity (BV) were assessed in blood samples drawn from the antecubital vein. RESULTS: B-CVD group showed higher fibrinogen values (p < 0.005) and higher mean venous pressure (0 < 0.0001) in comparison to controls, while U-CVD did not. No difference was found between both groups and controls for all the other parameters. CONCLUSIONS: Increased fibrinogen levels in patients with bilateral varicose veins may represent an early warning signal, as it could be associated to the long-term progression of chronic venous disease.

Tuning magnetic coupling in Sr2IrO4 thin films with epitaxial strain.

We report x-ray resonant magnetic scattering and resonant inelastic x-ray scattering studies of epitaxially strained Sr2IrO4 thin films. The films were grown on SrTiO3 and (LaAlO3)0.3(Sr2AlTaO6)0.7 substrates, under slight tensile and compressive strains, respectively. Although the films develop a magnetic structure reminiscent of bulk Sr2IrO4, the magnetic correlations are extremely anisotropic, with in-plane correlation lengths significantly longer than the out-of-plane correlation lengths. In addition, the compressive (tensile) strain serves to suppress (enhance) the magnetic ordering temperature TN, while raising (lowering) the energy of the zone-boundary magnon. Quantum chemical calculations show that the tuning of magnetic energy scales can be understood in terms of strain-induced changes in bond lengths.

Something more to say about calcium homeostasis: the role of vitamin K2 in vascular calcification and osteoporosis.

BACKGROUND: Vascular calcification and osteoporosis share similar etiopathogenetic mechanisms. Vitamin K2 deficiency could be responsible of the so called "calcium paradox", that is the lack of calcium in the bone and its storage in the vessel wall. These events may have clinically relevant consequences, such as cardiovascular accidents, and bone fractures. AIM: To review the biological function of vitamin K2 metabolism, the main factors related to its deficiency and the consequent clinical significance. DISCUSSION: Vitamin K2 is essential for the function of several proteins, involved in the maintenance of the normal structure of arterial wall, osteoarticular system, teeth, and for the regulation of cell growth. It has been demonstrated to have a pivotal role in the inhibition of vascular foci of calcification, and in the regulation of calcium deposition in the bone. Vitamin K2 deficiency is often subclinic in a large part of healthy population. This deficiency is related to the interaction of various factors, such as the reduced dietary intake, the alteration of intestinal absorption or production, with a possible role of intestinal microbiota and the increased consumption at the vessel wall. CONCLUSIONS: Vitamin K2 deficiency has recently been recognized as a protagonist in the development of vascular calcification and osteoporosis. Data reported so far are promising and, dietary supplementation seems a useful tool to contrast these diseases. However, large studies or solid clinical correlations regarding vitamin K2 deficiency and its pathologic consequences are needed to confirm these preliminary experiences.

Ultrasensitive magnetic field detection using a single artificial atom.

Efficient detection of magnetic fields is central to many areas of research and technology. High-sensitivity detectors are commonly built using direct-current superconducting quantum interference devices or atomic systems. Here we use a single artificial atom to implement an ultrasensitive magnetometer with micron range size. The artificial atom, a superconducting two-level system, is operated similarly to atom and diamond nitrogen-vacancy centre-based magnetometers. The high sensitivity results from quantum coherence combined with strong coupling to magnetic field. We obtain a sensitivity of 3.3 pT Hz(-1/2) for a frequency at 10 MHz. We discuss feasible improvements to increase sensitivity by one order of magnitude. The intrinsic sensitivity of this detector at frequencies in the 100 kHz-10 MHz range compares favourably with direct-current superconducting quantum interference devices and atomic magnetometers of equivalent spatial resolution. This result illustrates the potential of artificial quantum systems for sensitive detection and related applications.

Magnetic-field-induced nematic-nematic phase separation and droplet formation in colloidal goethite.

We demonstrate the suitability of polarization microscopy to study the recently discovered (parallel) nematic-(perpendicular) nematic phase separation. This novel type of phase transition is induced by applying an external magnetic field to a nematic liquid crystal of boardlike colloidal goethite and is due to an interplay between the intrinsic magnetic properties of goethite and the collective effect of liquid crystal formation. It is shown that the intense ochre colour of goethite does not preclude the use of polarization microscopy and interference colours, and that dichroism can give valuable qualitative information on the nature of the phases, their anchoring and their sedimentation and order parameter profiles. We also apply these techniques to study 'nematic-nematic tactoids': nematic droplets sedimenting within a nematic medium with mutually perpendicular orientations.

The isotropic-nematic interface of colloidal goethite in an external magnetic field.

Polarization microscopy was used to study the behavior around the isotropic-nematic interface of colloidal goethite dispersions in a magnetic field. It has been found before that the nematic phase is favored in an external field. In the case of goethite this was also observed; nematic droplets formed inside the isotropic phase and coalesced with the nematic phase. However, the behavior was found to be much richer because of the particle rotation around a certain critical field strength. The simultaneous occurrence of (parallel)nematic-(perpendicular)nematic phase separation under the influence of a magnetic field also plays a role here.

Probiotics: which and when?

There is a natural feeling between our intestinal flora and the gut. These microorganisms, living in the various tracts of human intestine, may affect the host homeostasis. Some of these bacteria can perhaps be a source of infection and sepsis when the bowel barrier is physically or functionally breached. The term 'probiotic' dates from the beginning of the last century and in the last years a market for probiotics worldwide, estimated to be worth billions of pounds, has developed. Although there is persuasive advertising for probiotics and there have been methodological advances in the study of the intestinal microbiota, much remains unproven, e.g. how probiotics work, which strains are effective, what can be expected to be achieved, and what dosage is required for effectiveness. This review of the literature is an evidence-based guide through the developing microbial universe affecting our life.

High dosage rifaximin for the treatment of small intestinal bacterial overgrowth.

BACKGROUND: Rifaximin is a broad spectrum non-absorbable antibiotic used for treatment of small intestinal bacterial overgrowth. Doses of 1200 mg/day showed a decontamination rate of 60% with low side-effects incidence. AIMS: To assess efficacy, safety and tolerability of rifaximin 1600 mg with respect to 1200 mg/day for small intestinal bacterial overgrowth treatment. METHODS: Eighty consecutive small intestinal bacterial overgrowth patients were enrolled. Diagnosis of small intestinal bacterial overgrowth based the clinical history and positivity to H(2)/CH(4) glucose breath test. Patients were randomized in two 7-day treatment groups: rifaximin 1600 mg (group 1); rifaximin 1200 mg (group 2). Glucose breath test was reassessed 1 month after. Compliance and side-effect incidence were also evaluated. RESULTS: One drop-out was observed in group 1 and two in group 2. Glucose breath test normalization rate was significantly higher in group 1 with respect to group 2 both in intention-to-treat (80% vs. 58%; P < 0.05) and per protocol analysis (82% vs. 61%; P < 0.05). No significant differences in patient compliance and incidence of side effects were found between groups. CONCLUSIONS: Rifaximin 1600 mg/day showed a significantly higher efficacy for small intestinal bacterial overgrowth treatment with respect to 1200 mg with similar compliance and side-effect profile.

Characterization of gene expression profile in rat Kupffer cells stimulated with IFN-alpha or IFN-gamma.

BACKGROUND AND AIM: Kupffer cells are intrasinusoidal space located macrophages with phagocytic capacity. Interferons are cytokines with antiviral, antiproliferative and immunomodulatory activities which may influence the activity of Kupffer cells. Aim of this study was to evaluate Kupffer cell gene expression after interferon-alpha or interferon-gamma stimulation in order to investigate a link between these cytokines and macrophage activation. METHODS: Rat Kupffer cells were cultured for 24 h and divided into three groups: unstimulated; stimulated with interferon-alpha and stimulated with interferon-gamma. After 8 h stimulation total RNA was extracted and processed according to Affymetrix protocols and hybridised on R34A microarray gene set. Data analyses was performed using Microarray Analysis Suite 5.0 software. Genes showing remarkably different expression in microarray analysis were confirmed by real-time PCR. RESULTS: Nearly 4000 out of the 8800 genes represented in the array were expressed by Kupffer cells. Among these, interferon-alpha up-regulates 91 genes by over two-fold (antiviral, antigen processing and presentation, and tumour suppressor/proapoptotic genes) and down-regulates 72 genes by 50% or more. Interferon-gamma up-regulates 70 genes by over two-fold and down-regulates 78 genes by 50% or more. Most of the genes induced by interferon-alpha are also induced by interferon-gamma. Down-regulated genes include growth factors and genes involved in cell cycle/proliferation. Real-time PCR confirms the results of the array. CONCLUSION: Interferons directly target rat Kupffer cells and are involved in the regulation of a wide variety of genes. Their expression profile shed light onto molecular mechanism of Kupffer cells activation in specific pathways such as antiviral and antitumour processes.

High-contrast dispersive readout of a superconducting flux qubit using a nonlinear resonator.

We demonstrate high-contrast state detection of a superconducting flux qubit. Detection is realized by probing the microwave transmission of a nonlinear resonator, based on a SQUID. Depending on the driving strength of the resonator, the detector can be operated in the monostable or the bistable mode. The bistable operation combines high-sensitivity with intrinsic latching. The measured contrast of Rabi oscillations is as high as 87%; of the missing 13%, only 3% of the loss of contrast is unaccounted for. Experiments involving two consecutive detection pulses are consistent with preparation of the qubit state by the first measurement.

Growth hormone in inflammatory bowel disease.

Crohn's disease and ulcerative colitis are inflammatory diseases of the gastrointestinal tract characterized by chronic relapsing inflammation and catabolism. Growth hormone/insulin-like growth factor-I axis is important in inflammatory bowel disease, because of the effects on epithelial cell kinetics, collagen deposition and immunomodulation. The potential of growth hormone as a therapeutic option in inflammatory bowel disease has been proven in various clinical settings. Acquired growth hormone resistance in inflammatory bowel disease seems to be mediated by a combination of undernutrition and active inflammation. In particular, proinflammatory cytokines, such as TNF-a and interleukin-6, have been implicated as potential mediators of growth hormone resistance. The introduction of anti-TNF-alpha monoclonal antibodies has proven very efficacious in patients with inflammatory bowel disease. By reducing cytokines levels in inflammatory cells of intestinal mucosa, infliximab could interfere with cytokine-induced growth hormone resistance. Recent in vivo data have shown that acquired growth hormone resistance in patients with inflammatory bowel disease may be reversed after the administration of anti-TNF-alpha therapy.

Hydrogen glucose breath test to detect small intestinal bacterial overgrowth: a prevalence case-control study in irritable bowel syndrome.

BACKGROUND: Studies assessing the prevalence of small intestinal bacterial overgrowth in irritable bowel syndrome gave contrasting results. Differences in criteria to define irritable bowel syndrome patients and methods to assess small intestinal bacterial overgrowth may explain different results. Moreover, no data exist on small intestinal bacterial overgrowth prevalence in a significant population of healthy non-irritable bowel syndrome subjects. AIM: To assess the prevalence of small intestinal bacterial overgrowth by glucose breath test in patients with irritable bowel syndrome symptoms with respect to a consistent control group. METHODS: Consecutive patients with irritable bowel syndrome according to Rome II criteria were enrolled. The control population consisted of 102 sex- and age-matched healthy subjects without irritable bowel syndrome symptoms. All subjects underwent glucose breath test. A peak of H2 values >10 p.p.m above the basal value after 50 g of glucose ingestion was considered suggestive of small intestinal bacterial overgrowth. RESULTS: A total of 65 irritable bowel syndrome patients and 102 healthy controls were enrolled. Positivity to glucose breath test was found in 31% of irritable bowel syndrome patients with respect to 4% in the control group, the difference between groups resulting statistically significant (OR: 2.65; 95% CI: 3.5-33.7, P < 0.00001). CONCLUSIONS: The present case-control study showed an epidemiological association between irritable bowel syndrome and small intestinal bacterial overgrowth. Placebo-controlled small intestinal bacterial overgrowth-eradication studies are necessary to clarify the real impact of small intestinal bacterial overgrowth on irritable bowel syndrome symptoms.

Hepatic steatosis and vascular disease.

Nonalcoholic fatty liver disease (NAFLD) refers to a wide picture of liver damage, ranging from steatosis to steatohepatitis, fibrosis and cirrhosis. The epidemiological studies demonstrated an association of NAFLD with obesity, type 2 diabetes and hyperlipidemia. Under this light the metabolic syndrome (MS), including NAFLD, obesity, central fat distribution, diabetes, dyslipidemia, hypertension and atherosclerotic cardiovascular disease (CVD) can be considered the link to explain the presence of vascular diseases in patients with NAFLD. In NHANES III, the authors demonstrated that the presence of MS was associated with increased risk of myocardial infarction, stroke or both. In a prospective study on 1209 Finnish middle-aged men without CVD or diabetes at baseline, Lakka showed that MS per se is associated with an increased risk of CVD and all-cause mortality. Finally the Atherosclerosis Risk in Communities (ARIC) confirmed that subjects with MS were 2 times more likely to have prevalent coronary heart disease. From a pathophysiological point of view, growing evidences implicate the oxidative stress as the unifying mechanism for many CVD risk factors. Under this light there is emerging evidence suggesting that there is a significant increase in vascular oxidative stress in patients with MS, with the presence of endothelial dysfunction in the early stage of the syndrome. Indeed, the inflammation process evidentiated in these patients is initiated at the endothelial level, stressing the key role of this active and dynamic tissue in the pathophysiological pathways. Under this light the endothelium can be considered as the last effector of a multi-syndrome and the main target of all the future studies focused on the underlying mechamisms of this complex network. Because of the potential serious public health impact, the comprehension of these patophysiological pathways will be crucial to design new preventive measures and therapeutic strategies.

Rifaximin dose-finding study for the treatment of small intestinal bacterial overgrowth.

BACKGROUND: Few controlled studies assessing choice and duration of antibiotic therapy for small intestinal bacterial overgrowth are available. AIM: To assess efficacy, safety and tolerability of different doses of rifaximin, a broad spectrum non-absorbable antibiotic, for intestinal bacterial overgrowth eradication. METHODS: We enrolled 90 consecutive patients affected by small intestinal bacterial overgrowth. The presence of small intestinal bacterial overgrowth was based on the occurrence of a rise of H2 values >12 p.p.m. above the basal value after 50 g glucose ingestion. Patients were randomized in three 7-day treatment groups: rifaximin 600 mg/day (group 1); rifaximin 800 mg/day (group 2) and rifaximin 1200 mg/day (group 3). Glucose breath test was reassessed 1 month after the end of therapy. Compliance to the treatment and incidence of side-effects were also evaluated. RESULTS: No drop-outs were observed in the three groups. Glucose breath test normalization rate was significantly higher in group 3 (60%) with respect to group 1 (17%; P < 0.001) and group 2 (27%, P < 0.01). No significant differences in patient compliance and incidence of side-effects were found among groups. CONCLUSIONS: Higher doses of rifaximin lead to a significant gain in terms of therapeutic efficacy in small intestinal bacterial overgrowth eradication without increasing the incidence of side-effects.

Abnormal breath tests to lactose, fructose and sorbitol in irritable bowel syndrome may be explained by small intestinal bacterial overgrowth.

BACKGROUND: Small intestinal bacterial overgrowth and sugar malabsorption (lactose, fructose, sorbitol) may play a role in irritable bowel syndrome. The lactulose breath test is a reliable and non-invasive test for the diagnosis of small intestinal bacterial overgrowth. The lactose, fructose and sorbitol hydrogen breath tests are widely used to detect specific sugar malabsorption. AIM: To assess the extent to which small intestinal bacterial overgrowth may influence the results of hydrogen sugar breath tests in irritable bowel syndrome patients. METHODS: We enrolled 98 consecutive irritable bowel syndrome patients. All subjects underwent hydrogen lactulose, lactose, fructose and sorbitol hydrogen breath tests. Small intestinal bacterial overgrowth patients were treated with 1-week course of antibiotics. All tests were repeated 1 month after the end of therapy. RESULTS: A positive lactulose breath test was found in 64 of 98 (65%) subjects; these small intestinal bacterial overgrowth patients showed a significantly higher prevalence of positivity to the lactose breath test (P < 0.05), fructose breath test (P < 0.01) and sorbitol breath test (P < 0.01) when compared with the small intestinal bacterial overgrowth-negatives. Small intestinal bacterial overgrowth eradication, as confirmed by negative lactulose breath test, caused a significant reduction in lactose, fructose and sorbitol breath tests positivity (17% vs. 100%, 3% vs. 62%, and 10% vs. 71% respectively: P < 0.0001). CONCLUSIONS: In irritable bowel syndrome patients with small intestinal bacterial overgrowth, sugar breath tests may be falsely abnormal. Eradication of small intestinal bacterial overgrowth normalizes sugar breath tests in the majority of patients. Testing for small intestinal bacterial overgrowth should be performed before other sugar breath tests tests to avoid sugar malabsorption misdiagnosis.

Helicobacter pylori infection and ischaemic heart disease: an overview of the general literature.

In the last years, a considerable number of studies have been performed on the correlation between Helicobacter pylori infection and ischaemic heart disease. The reason is the supposed role of some chronic infections in the genesis and development of vessel wall injury and atheromatous plaque, as already reported for Chlamydia pneumoniae and herpes viruses. While this association may be theoretically conceivable, it still remains debated from a practical point of view. Epidemiological and animal studies as well as some eradicating trials gave conflicting results, while studies investigating the specific molecular mimicry mechanisms induced by H. pylori strongly support the association. Moreover, none of the studies performed so far did take into account the effect of the genetic susceptibility to develop ischaemic heart disease or to respond to H. pylori infection. In particular, while the exposure to some known risk factor for atherosclerosis should lead to develop ischaemic heart disease, no condition or exposure, either individual or in combination, completely explains the occurrence and the progression of the disease, as many patients develop ischaemic heart disease in the absence of any risk factor. Based on these concepts, can we state that H. pylori infection may cause the same effect in patients with ischaemic heart disease as in healthy subjects? Further studies are needed in order to clarify this issue.

Nondestructive readout for a superconducting flux qubit.

We present a new readout method for a superconducting flux qubit, based on the measurement of the Josephson inductance of a superconducting quantum interference device that is inductively coupled to the qubit. The intrinsic flux detection efficiency and backaction are suitable for a fast and nondestructive determination of the quantum state of the qubit, as needed for readout of multiple qubits in a quantum computer. We performed spectroscopy of a flux qubit and we measured relaxation times of the order of 80 micros.