Quantum enhanced positioning and clock synchronization

A wide variety of positioning and ranging procedures are based on repeatedly sending electromagnetic pulses through space and measuring their time of arrival. This paper shows that quantum entanglement and squeezing can be employed to overcome the classical power/bandwidth limits on these procedures, enhancing their accuracy. Frequency entangled pulses could be used to construct quantum positioning systems (QPS), to perform clock synchronization, or to do ranging (quantum radar): all of these techniques exhibit a similar enhancement compared with analogous protocols that use classical light. Quantum entanglement and squeezing have been exploited in the context of interferometry, frequency measurements, lithography, and algorithms. Here, the problem of positioning a party (say Alice) with respect to a fixed array of reference points will be analyzed.Comment: 4 pages, 2 figures. Accepted for publication by Natur

Quantum interferometry with three-dimensional geometry

Quantum interferometry uses quantum resources to improve phase estimation with respect to classical methods. Here we propose and theoretically investigate a new quantum interferometric scheme based on three-dimensional waveguide devices. These can be implemented by femtosecond laser waveguide writing, recently adopted for quantum applications. In particular, multiarm interferometers include "tritter" and "quarter" as basic elements, corresponding to the generalization of a beam splitter to a 3- and 4-port splitter, respectively. By injecting Fock states in the input ports of such interferometers, fringe patterns characterized by nonclassical visibilities are expected. This enables outperforming the quantum Fisher information obtained with classical fields in phase estimation. We also discuss the possibility of achieving the simultaneous estimation of more than one optical phase. This approach is expected to open new perspectives to quantum enhanced sensing and metrology performed in integrated photonic.Comment: 7 pages (+4 Supplementary Information), 5 figure

Photonic quantum technologies

The first quantum technology, which harnesses uniquely quantum mechanical effects for its core operation, has arrived in the form of commercially available quantum key distribution systems that achieve enhanced security by encoding information in photons such that information gained by an eavesdropper can be detected. Anticipated future quantum technologies include large-scale secure networks, enhanced measurement and lithography, and quantum information processors, promising exponentially greater computation power for particular tasks. Photonics is destined for a central role in such technologies owing to the need for high-speed transmission and the outstanding low-noise properties of photons. These technologies may use single photons or quantum states of bright laser beams, or both, and will undoubtably apply and drive state-of-the-art developments in photonics

Recommended care received by geriatric hip fracture patients: where are we now and where are we heading?

INTRODUCTION: Despite the availability of clinical guidelines on the prevention and treatment of geriatric hip fractures, the percentage of recommended care received by patients is low. We conducted an importance-performance analysis for prioritizing interventions to improve the in-hospital management of these patients. MATERIALS AND METHODS: A secondary data analysis was conducted on the in-hospital treatment of 540 geriatric hip fracture patients in 34 hospitals in Belgium, Italy, and Portugal. First, we assessed the level of expert consensus on the process indicators composing international guidelines on hip fracture treatment. Second, guideline adherence on in-hospital care was evaluated within and across hospitals. Third, an importance-performance analysis was conducted, linking expert consensus to guideline adherence. RESULTS: Level of expert consensus was high (above 75%) for 12 of 22 process indicators identified from the literature. There is large between and within hospital variation in guideline adherence for these indicators and for none of the 540 patients were all 22 process indicators adhered to. Importance-performance analysis demonstrated that three indicators that had a high level of expert consensus also had a high level of adherence (above 80%). Nine indicators, most of which have been previously linked to patient outcomes, had a high level of expert consensus but a consistently low level of adherence across hospitals and are identified as priority areas for improvement. CONCLUSIONS: Guideline adherence for the treatment of geriatric hip fracture patients is remarkably suboptimal. Importance-performance analysis is a useful strategic approach to assist practitioners and healthcare managers to improve the quality of care.status: publishe

III–V quantum light source and cavity-QED on Silicon

Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects, is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon’s indirect band-gap. III–V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III–V material grown directly on silicon substrates. The high quality of the III–V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems

Minimal impact of a care pathway for geriatric hip fracture patients

BACKGROUND: Adherence to guidelines for patients with proximal femur fracture is suboptimal. OBJECTIVE: To evaluate the effect of a care pathway for the in-hospital management of older geriatric hip fracture patients on adherence to guidelines and patient outcomes. DESIGN: The European Quality of Care Pathways study is a cluster randomized controlled trial. SETTING: 26 hospitals in Belgium, Italy and Portugal. SUBJECTS: Older adults with a proximal femur fracture (n = 514 patients) were included. METHODS: Hospitals treating older adults (>65) with a proximal femur fracture were randomly assigned to an intervention group, i.e. implementation of a care pathway, or control group, i.e. usual care. Thirteen patient outcomes and 24 process indicators regarding in-hospital management, as well as three not-recommended care activities were measured. Adjusted and unadjusted regression analyses were conducted using intention-to-treat procedures. RESULTS: In the intervention group 301 patients in 15 hospitals were included, and in the control group 213 patients in 11 hospitals. Sixty-five percent of the patients were older than 80 years. The implementation of this care pathway had no significant impact on the thirteen patient outcomes. The preoperative management improved significantly. Eighteen of 24 process indicators improved, but only two improved significantly. Only for a few teams a geriatrician was an integral member of the treatment team. DISCUSSION: Implementation of a care pathway improved compliance to evidence, but no significant effect on patient outcomes was found. The impact of the collaboration between surgeons and geriatricians on adherence to guidelines and patient outcomes should be studied. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00962910.status: Published onlin