High-fidelity laser-free universal control of trapped ion qubits.

Universal control of multiple qubits-the ability to entangle qubits and to perform arbitrary individual qubit operations1-is a fundamental resource for quantum computing2, simulation3 and networking4. Qubits realized in trapped atomic ions have shown the highest-fidelity two-qubit entangling operations5-7 and single-qubit rotations8 so far. Universal control of trapped ion qubits has been separately demonstrated using tightly focused laser beams9-12 or by moving ions with respect to laser beams13-15, but at lower fidelities. Laser-free entangling methods16-20 may offer improved scalability by harnessing microwave technology developed for wireless communications, but so far their performance has lagged the best reported laser-based approaches. Here we demonstrate high-fidelity laser-free universal control of two trapped-ion qubits by creating both symmetric and antisymmetric maximally entangled states with fidelities of [Formula: see text] and [Formula: see text], respectively (68 per cent confidence level), corrected for initialization error. We use a scheme based on radiofrequency magnetic field gradients combined with microwave magnetic fields that is robust against multiple sources of decoherence and usable with essentially any trapped ion species. The scheme has the potential to perform simultaneous entangling operations on multiple pairs of ions in a large-scale trapped-ion quantum processor without increasing control signal power or complexity. Combining this technology with low-power laser light delivered via trap-integrated photonics21,22 and trap-integrated photon detectors for qubit readout23,24 provides an opportunity for scalable, high-fidelity, fully chip-integrated trapped-ion quantum computing.

Double faecal immunochemical testing in patients with symptoms suspicious of colorectal cancer.

BACKGROUND: Faecal immunochemical test (FIT)-directed pathways based on a single test have been implemented for symptomatic patients. However, with a single test, the sensitivity is 87 per cent at 10 µg haemoglobin (Hb) per g faeces. This aims of this study were to define the diagnostic performance of a single FIT, compared with double FIT in symptomatic populations. METHODS: Two sequential prospective patient cohorts referred with symptoms from primary care were studied. Patients in cohort 1 were sent a single FIT, and those in cohort 2 received two tests in succession before investigation. All patients were investigated, regardless of having a positive or negative test (threshold 10 µg Hb per g). RESULTS: In cohort 1, 2260 patients completed one FIT and investigation. The sensitivity of single FIT was 84.1 (95 per cent c.i. 73.3 to 91.8) per cent for colorectal cancer and 67.4 (61.0 to 73.4) per cent for significant bowel pathology. In cohort 2, 3426 patients completed at least one FIT, and 2637 completed both FITs and investigation. The sensitivity of double FIT was 96.6 (90.4 to 99.3) per cent for colorectal cancer and 83.0 (77.4 to 87.8) per cent for significant bowel pathology. The second FIT resulted in a 50.0 per cent reduction in cancers missed by the first FIT, and 30.0 per cent for significant bowel pathology. Correlation between faecal Hb level was only modest (rs = 0.58), and 16.8 per cent of double tests were discordant, 11.4 per cent in patients with colorectal cancer and 18.3 per cent in those with significant bowel pathology. CONCLUSION: FIT in patients with high-risk symptoms twice in succession reduces missed significant colorectal pathology and has an acceptable workload impact.

Chained Bell Inequality Experiment with High-Efficiency Measurements.

We report correlation measurements on two ^{9}Be^{+} ions that violate a chained Bell inequality obeyed by any local-realistic theory. The correlations can be modeled as derived from a mixture of a local-realistic probabilistic distribution and a distribution that violates the inequality. A statistical framework is formulated to quantify the local-realistic fraction allowable in the observed distribution without the fair-sampling or independent-and-identical-distributions assumptions. We exclude models of our experiment whose local-realistic fraction is above 0.327 at the 95% confidence level. This bound is significantly lower than 0.586, the minimum fraction derived from a perfect Clauser-Horne-Shimony-Holt inequality experiment. Furthermore, our data provide a device-independent certification of the deterministically created Bell states.

High-Fidelity Universal Gate Set for

We report high-fidelity laser-beam-induced quantum logic gates on magnetic-field-insensitive qubits comprised of hyperfine states in ^{9}Be^{+} ions with a memory coherence time of more than 1 s. We demonstrate single-qubit gates with an error per gate of 3.8(1)×10^{-5}. By creating a Bell state with a deterministic two-qubit gate, we deduce a gate error of 8(4)×10^{-4}. We characterize the errors in our implementation and discuss methods to further reduce imperfections towards values that are compatible with fault-tolerant processing at realistic overhead.

Preparation of Entangled States through Hilbert Space Engineering.

We apply laser fields to trapped atomic ions to constrain the quantum dynamics from a simultaneously applied global microwave field to an initial product state and a target entangled state. This approach comes under what has become known in the literature as "quantum Zeno dynamics" and we use it to prepare entangled states of two and three ions. With two trapped ^{9}Be^{+} ions, we obtain Bell state fidelities up to 0.990_{-5}^{+2}; with three ions, a W-state fidelity of 0.910_{-7}^{+4} is obtained. Compared to other methods of producing entanglement in trapped ions, this procedure can be relatively insensitive to certain imperfections such as fluctuations in laser intensity.

Multicentre survey of radiologically inserted gastrostomy feeding tube (RIG) in the UK.

AIMS: To evaluate the variance in current UK clinical practice and clinical outcomes for direct percutaneous radiologically inserted gastrostomy (RIG). MATERIALS AND METHODS: A prospective UK multicentre survey of RIG performed between October 2008 and August 2010 was performed through the British Society of Gastrointestinal and Abdominal Radiology (BSGAR). RESULTS: Data from 684 patients were provided by 45 radiologists working at 17 UK centres. Two hundred and sixty-three cases (40%) were performed with loop-retained catheters, and 346 (53%) with balloon-retained devices. Sixty percent of all patients experienced pain in the first 24 h, but settled in the majority thereafter. Early complications, defined as occurring in the first 24 h, included minor bleeding (1%), wound infection (3%), peritonism (2%), and tube misplacement (1%). Late complications, defined as occurring between day 2 and day 30 post-procedure, included mild pain (30%), persisting peritonism (2%), and 30 day mortality of 1% (5/665). Pre-procedural antibiotics or anti-methicillin-resistant Staphylococcus aureus (MRSA) prophylaxis did not affect the rate of wound infection, peritonitis, post-procedural pain, or mortality. Ninety-three percent of cases were performed using gastropexy. Gastropexy decreased post-procedural pain (p < 0.001), but gastropexy-related complications occurred in 5% of patients. However, post-procedure pain increased with the number of gastropexy sutures used (p < 0.001). The use of gastropexy did not affect the overall complication rate or mortality. Post-procedure pain increased significantly as tube size increased (p < 0.001). The use of balloon-retention feeding tubes was associated with more pain than the deployment of loop-retention devices (p < 0.001). CONCLUSION: RIG is a relatively safe procedure with a mortality of 1%, with or without gastropexy. Pain is the commonest complication. The use of gastropexy, fixation dressing or skin sutures, smaller tube sizes, and loop-retention catheters significantly reduced the incidence of pain. There was a gastropexy-related complication rate in 5% of patients. Neither pre-procedural antibiotics nor anti-MRSA prophylaxis affected the rate of wound infection.

Accuracy of minimal-preparation computerized tomography in the investigation of suspected colorectal cancer in frail patients: the experience of Western General Hospital, Edinburgh.

Traditional methods of investigating suspected colorectal carcinoma (CRC) such as barium enema, colonoscopy and computerized tomography (CT) pneumocolon are often poorly tolerated by frail or elderly patients. Comparatively, minimal-preparation CT (MPCT) is a non-invasive investigation that does not require bowel preparation. The aim of this study was to review MPCTs carried out at the Western General Hospital, Edinburgh, and compare findings with current published data. Retrospective analysis of 85 patients (age range 55-99 years) who underwent MPCTs at the Western General Hospital between May 2005 and June 2008 was undertaken. Results were followed up using clinical notes, pathological and surgical databases. Subsequent outcomes were analysed (average follow-up 22 months). The prevalence of CRC within the study cohort was 0.14. Sensitivity of MPCT was 1 (95% confidence interval [CI], 0.69-1) with a specificity of 0.93 (95% CI, 0.84-0.97). Thirty percent of patients were found to have extracolonic findings requiring further investigation or intervention. Of the patients, 4.7% had an extracolonic malignancy diagnosed on MPCT. MPCT is a sensitive and specific method of investigating CRC in the elderly, infirm or immobile. Our results were found to be comparable with that of current published data, validating the service provided at the Western General Hospital.

Quantum state tomography of an itinerant squeezed microwave field.

We perform state tomography of an itinerant squeezed state of the microwave field prepared by a Josephson parametric amplifier (JPA). We use a second JPA as a preamplifier to improve the quantum efficiency of the field quadrature measurement from 2% to 36%±4%. Without correcting for the detection inefficiency we observe a minimum quadrature variance which is 68(-7)(+9)% of the variance of the vacuum. We reconstruct the state's density matrix by a maximum likelihood method and infer that the squeezed state has a minimum variance less than 40% of the vacuum, with uncertainty mostly caused by calibration systematics.

The use of ultrasound to diagnose hepatic steatosis in type 2 diabetes: intra- and interobserver variability and comparison with magnetic resonance spectroscopy.

AIM: To compare ultrasound gradings of steatosis with fat fraction (FF) on magnetic resonance spectroscopy (MRS; the non-invasive reference standard for quantification of hepatic steatosis), and evaluate inter- and intraobserver variability in the ultrasound gradings. MATERIALS AND METHODS: Triple grading of hepatic ultrasound examination was performed by three independent graders on 131 people with type 2 diabetes. The stored images of 60 of these individuals were assessed twice by each grader on separate occasions. Fifty-eight patients were pre-selected on the basis of ultrasound grading (normal, indeterminate/mild steatosis, or severe steatosis) to undergo (1)H-MRS. The sensitivity and specificity of the ultrasound gradings were determined with reference to MRS data, using two cut-offs of FF to define steatosis, ≥9% and ≥6.1%. RESULTS: Median (intraquartile range) MRS FF (%) in the participants graded on ultrasound as normal, indeterminate/mild steatosis, and severe steatosis were 4.2 (1.2-5.7), 4.1 (3.1-8.5) and 19.4 (12.9-27.5), respectively. Using a liver FF of ≥6.1% on MRS to denote hepatic steatosis, the unadjusted sensitivity and specificity of ultrasound gradings (severe versus other grades of steatosis) were 71 and 100%, respectively. Interobserver agreement within one grade was observed in 79% of cases. Exact intraobserver agreement ranged from 62 to 87%. CONCLUSION: Hepatic ultrasound provided a good measure of the presence of significant hepatic steatosis with good intra- and interobserver agreement. The grading of a mildly steatotic liver was less secure and, in particular, there was considerable overlap in hepatic FF with those who had a normal liver on ultrasound.

All-optical generation of states for "Encoding a qubit in an oscillator".

Most quantum computation schemes propose encoding qubits in two-level systems. Others exploit the use of an infinite-dimensional system. In "Encoding a qubit in an oscillator" [Phys. Rev. A 64, 012310 (2001)], Gottesman, Kitaev, and Preskill (GKP) combined these approaches when they proposed a fault-tolerant quantum computation scheme in which a qubit is encoded in the continuous position and momentum degrees of freedom of an oscillator. One advantage of this scheme is that it can be performed by use of relatively simple linear optical devices, squeezing, and homodyne detection. However, we lack a practical method to prepare the initial GKP states. Here we propose the generation of an approximate GKP state by using superpositions of optical coherent states (sometimes called "Schrödinger cat states"), squeezing, linear optical devices, and homodyne detection.

Faecal Calprotectin and Magnetic Resonance Enterography in Ileal Crohn's Disease: Correlations Between Disease Activity and Long-Term Follow-Up.

BACKGROUND AND AIMS: Magnetic resonance enterography [MRE] is the gold standard for assessing ileal inflammation in Crohn's disease [CD]. The aim of the present study was to correlate faecal calprotectin [FC] to MRE via a simple score in an exclusive ileal cohort with long-term follow-up for association with time to surgery or biologic therapy. METHODS: In total, 150 MRE studies with matched FC [±30 days] were identified from the Edinburgh FC Register [2008-12; n = 18138]. Scans were re-read blinded to clinical data, independently, by two expert gastrointestinal radiologists, to generate a simple MRE score [range 0-10] from assessment of the worst intestinal segment plus total disease extent. RESULTS: In total, 119 MRE scans were evaluated from 104 patients with ileal CD [L1 or L3 with panproctocolectomy]. Receiver operating characteristic analysis showed an area under the curve of 0.77 [0.67-0.87, p < 0.0001] for FC and MRE score >1, with an optimal cut-off of 145 µg/g for severe inflammation on MRE with 69.3% [57.6-79.5] sensitivity and 71.4% [53.7-85.4] specificity. Long-term follow-up over a median [interquartile range] of 2086 days [1786-2353] revealed FC ≥ 145 µg/g was associated with reduced biologic-free survival until 3 years following MRE, whereas MRE score [severe vs absent] was associated with reduced surgery- and biologic-free survival throughout follow-up. Backwards stepwise logistic regression revealed that length of ileal disease (odds ratio [OR] 3.8, 1.1-13.2, p = 0.034) and increased bowel wall thickness at MRE [OR 4.2, 1.6-10.7, p < 0.0001] or female sex [OR 5.2, 1.5-18.7, p = 0.011] increased the risk of biologic use or surgery, respectively. CONCLUSIONS: FC correlates well with MRE assessment of ileal CD with MRE parameters associated with long-term biologic- and surgery-free remission.

Self-expanding metallic stent insertion in the proximal colon.

OBJECTIVE: Colonic obstruction may be relieved by the insertion of a self-expanding metallic stent (SEMS), either for permanent palliative relief or as a bridge to surgery. Lesions proximal to the descending colon can be more difficult to intubate and stent [1]. SEMS placement in the more proximal colon lesions has been reported in only a few cases [2,4]. The aim of this study was to review the outcome of SEMS for obstruction at the splenic flexure and above. METHOD: A study of all colonic stents inserted in one specialist unit was undertaken. Patients' demographics, site and aetiology of the underlying obstruction, success or other outcome of the procedures were collected. Thirty-day morbidity and mortality were documented. RESULTS: Seven patients had proximal lesions: four in the transverse colon and three at the splenic flexure. Six patients had colorectal carcinoma and one had extrinsic compression from a gastric carcinoma. Six of the SEMS were inserted for permanent palliation, and one as a bridge to surgery. Stent placement was technically successful in six of the seven patients. In the seventh patient, there was a failure of expansion of the stent, after successful intubation of the lesion, which was in the distal transverse colon. One patient suffered from minor self-limiting abdominal pain in the first 24 h after the procedure. There was no other SEMS related morbidity or mortality. All of the successfully stented patients were discharged from the surgical ward within 3 days after the procedure. Median survival time was 4.3 months (range 3-12 months). Three patients are still alive. CONCLUSION: The SEMS is a useful tool in managing acute bowel obstruction. Placement of colonic stents proximal to the descending colon is safe, feasible and effective.

Quadrature histograms in maximum-likelihood quantum state tomography.

Quantum state tomography aims to determine the quantum state of a system from measured data and is an essential tool for quantum information science. When dealing with continuous variable quantum states of light, tomography is often done by measuring the field amplitudes at different optical phases using homodyne detection. The quadrature-phase homodyne measurement outputs a continuous variable, so to reduce the computational cost of tomography, researchers often discretize the measurements. We show that this can be done without significantly degrading the fidelity between the estimated state and the true state. This paper studies different strategies for determining the histogram bin widths. We show that computation time can be significantly reduced with little loss in the fidelity of the estimated state when the measurement operators corresponding to each histogram bin are integrated over the bin width.

Investigating bias in maximum-likelihood quantum-state tomography.

Maximum-likelihood quantum-state tomography yields estimators that are consistent, provided that the likelihood model is correct, but the maximum-likelihood estimators may have bias for any finite data set. The bias of an estimator is the difference between the expected value of the estimate and the true value of the parameter being estimated. This paper investigates bias in the widely used maximum-likelihood quantum-state tomography. Our goal is to understand how the amount of bias depends on factors such as the purity of the true state, the number of measurements performed, and the number of different bases in which the system is measured. For this, we perform numerical experiments that simulate optical homodyne tomography of squeezed thermal states under various conditions, perform tomography, and estimate bias in the purity of the estimated state. We find that estimates of higher purity states exhibit considerable bias, such that the estimates have lower purities than the true states.

Clinically significant chronic liver disease in people with Type 2 diabetes: the Edinburgh Type 2 Diabetes Study.

BACKGROUND: Type 2 diabetes is an independent risk factor for chronic liver disease, however disease burden estimates and knowledge of prognostic indicators are lacking in community populations. AIMS: To describe the prevalence and incidence of clinically significant chronic liver disease amongst community-based older people with Type 2 diabetes and to determine risk factors which might assist in discriminating patients with unknown prevalent or incident disease. DESIGN: Prospective cohort study. METHODS: Nine hundred and thirty-nine participants in the Edinburgh Type 2 Diabetes Study underwent investigation including liver ultrasound and non-invasive measures of non-alcoholic steatohepatitis (NASH), hepatic fibrosis and systemic inflammation. Over 6-years, cases of cirrhosis and hepatocellular carcinoma were collated from multiple sources. RESULTS: Eight patients had known prevalent disease with 13 further unknown cases identified (prevalence 2.2%) and 15 incident cases (IR 2.9/1000 person-years). Higher levels of systemic inflammation, NASH and hepatic fibrosis markers were associated with both unknown prevalent and incident clinically significant chronic liver disease (allP < 0.001). CONCLUSIONS: Our study investigations increased the known prevalence of clinically significant chronic liver disease by over 150%, confirming the suspicion of a large burden of undiagnosed disease. The disease incidence rate was lower than anticipated but still much higher than the general population rate. The ability to identify patients both with and at risk of developing clinically significant chronic liver disease allows for early intervention and clinical monitoring strategies. Ongoing work, with longer follow-up, including analysis of rates of liver function decline, will be used to define optimal risk prediction tools.

Technical advances in studying cardiac electrophysiology - Role of rabbit models.

Cardiovascular research has made a major contribution to an unprecedented 10 year increase in life expectancy during the last 50 years: most of this increase due to a decline in mortality from heart disease and stroke. The majority of the basic cardiovascular science discoveries, which have led to this impressive extension of human life, came from investigations conducted in various small and large animal models, ranging from mouse to pig. The small animal models are currently popular because they are amenable to genetic engineering and are relatively inexpensive. The large animal models are favored at the translational stage of the investigation, as they are anatomically and physiologically more proximal to humans, and can be implanted with various devices; however, they are expensive and less amenable to genetic manipulations. With the advent of CRISPR genetic engineering technology and the advances in implantable bioelectronics, the large animal models will continue to advance. The rabbit model is particularly poised to become one of the most popular among the animal models that recapitulate human heart diseases. Here we review an array of the rabbit models of atrial and ventricular arrhythmias, as well as a range of the imaging and device technologies enabling these investigations.

Transient synovitis: is there a need to aspirate hip joint effusions?

There is debate as to the optimal management of children with hip joint effusions especially regarding the decision to aspirate. The objective of this study was to determine whether there is a need to aspirate hip joint effusions detected on ultrasound in patients with clinical transient synovitis (TS) and to identify the natural history of these effusions. Twenty-five children with proven hip joint effusions were followed up sequentially by clinical and radiological examination until symptom free. The mean age was 6 years with equal right/left distribution. No child underwent hip aspiration and no cases of sepsis were missed. The median size of hip effusion detected on ultrasound at presentation was 9 mm. At 7 days 60% (15/25) of patients had a normal clinical examination with no detectable effusion on ultrasound. At 14 days 16% (4/25) had an effusion detectable on ultrasound but they were all pain and limp free and their effusions were reducing in size. These results support the known benign nature of TS and that it will settle with conservative treatment.

Prevalence and markers of advanced liver disease in type 2 diabetes.

BACKGROUND: Type 2 diabetes is a risk factor for progression of non-alcoholic fatty liver disease (NAFLD) to fibrosis and cirrhosis. We examined the prevalence of advanced liver disease in people with type 2 diabetes and analysed the effectiveness of liver function tests (LFTs) as a screening tool. METHODS: Participants (n = 939, aged 61-76 years) from the Edinburgh Type 2 Diabetes Study, a randomly selected population of people with type 2 diabetes, underwent abdominal ultrasonography. Hyaluronic acid (HA) and platelet count/spleen diameter ratio (PSR) were used as non-invasive markers of hepatic fibrosis and portal hypertension. Subjects were screened for secondary causes of liver disease that excluded them from a diagnosis of NAFLD. The efficacy of LFTs [alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT)] in screening for liver disease was determined. RESULTS: Cirrhosis was identified by ultrasound in four participants (0.4%). Ten (1.1%) had evidence of portal hypertension (PSR < 909), and two (0.2%) had hepatocellular carcinoma. Fifty-three participants (5.7%) had evidence of hepatic fibrosis (HA > 100 ng/ml in the absence of joint disease); a further 169 had HA > 50 ng/ml. In participants with NAFLD-related fibrosis (HA > 100 ng/ml), 12.5% had an elevated ALT level and 17.5% had an elevated GGT level. CONCLUSION: The prevalence of hepatic fibrosis and cirrhosis were lower than expected. The use of LFTs to screen for liver disease missed most cases of fibrosis predicted by raised HA levels.

Magnetic resonance follow-through imaging for evaluation of disease activity in ileal Crohn's disease: an observational, retrospective cohort study.

BACKGROUND: Magnetic resonance follow-through (MRFT) is a new cross-sectional imaging modality with the potential to accurately stage ileal Crohn's disease (CD), while avoiding ionizing radiation and the discomfort associated with enteroclysis. We aimed to assess the reliability of this technique in assessing the extent and activity of ileal CD, and to assess its influence on subsequent management. METHODS: Out of a total of 342 patients undergoing MRFT between 2004 and 2008, 221 were performed in 191 patients with confirmed CD. Case notes were reviewed in detail with documentation of all investigations pre- and post-MRFT. Agreement between inflammatory markers, histopathology, and MRFT findings was determined. RESULTS: Overall, 116/221 (52.5%) of MRFTs showed active ileal CD, and 76/221 (34.4%) quiescent CD, while 29/221 (13.1%) were suboptimal. Overall, 66 strictures and 18 fistulae were identified. There was substantial agreement between active ileal CD on MRFT and histopathology (n = 59; kappa = 0.66; P = 0.0006; sensitivity 85.1%, specificity 85.7%) and fecal calprotectin (n = 14; kappa = 0.72; P = 0.047), while C-reactive protein (CRP) showed moderate agreement (n = 107; kappa = 0.402; P = 0.00028). Management was influenced by MRFT reports following active (52/84, 62% treated medically) or quiescent (48/62, 77.4% managed conservatively) disease. Fibrotic strictures were predominantly treated surgically (7/14, 50%). In all, 13/32 (40.6%) patients with inflammatory ileal strictures required surgery, mostly due to steroid-resistant disease. Overall, 75 MR findings were documented in 221 MRFTs, including 1 renal cancer. CONCLUSIONS: MRFT provides accurate information on ileal CD activity, with close agreement to inflammatory markers and histopathology. It represents a substantial advance in the staging of CD, while avoiding painful enteroclysis and radiation exposure in young patients.