Experimental multiphase estimation on a chip

Multiparameter estimation is a general problem that aims at measuring unknown physical quantities, obtaining high precision in the process. In this context, the adoption of quantum resources promises a substantial boost in the achievable performances with respect to the classical case. However, several open problems remain to be addressed in the multiparameter scenario. A crucial requirement is the identification of suitable platforms to develop and experimentally test novel efficient methodologies that can be employed in this general framework. We report the experimental implementation of a reconfigurable integrated multimode interferometer designed for the simultaneous estimation of two optical phases. We verify the high-fidelity operation of the implemented device, and demonstrate quantum-enhanced performances in two-phase estimation with respect to the best classical case, post-selected to the number of detected coincidences. This device can be employed to test general adaptive multiphase protocols due to its high reconfigurability level, and represents a powerful platform to investigate the multiparameter estimation scenario.Comment: 10+7 pages, 7+4 figure

An Active High Impedance Surface for Low Profile Tunable and Steerable Antennas

In this letter, an approach for designing a tunable and steerable antenna is presented. The antenna model is based on a wideband bow-tie radiating element mounted above an active Artificial Magnetic Conductor (AMC). The AMC geometry consists of a Frequency Selective Surface (FSS) printed on a thin grounded dielectric slab in which some chip-set varactor diodes are placed between the metallic elements and the backing plane through vias. The resulting antenna can be tuned over the S-Band by simply changing all varactor capacitances through an appropriate biasing voltage. Moreover, this structure can operate a beam scanning over each working frequency by applying an appropriate biasing voltage to the active elements of the AMC surface in accordance to leaky radiation principles. The low profile active antenna is characterized by an overall thickness of 5.32 mm, which corresponds to approximately lambda/24 at the centre of the operating band.Comment: 4 pages, 13 figures

Flammer Syndrome in Aesthetic Medicine: The Importance of Recognizing Signs and Symptoms

Purpose Flammer syndrome (FS), a clinical entity characterized by primary vascular dysregulation of blood flow together with various signs and symptoms, has been reported in both healthy individuals and those with certain diseases. Adequate management of FS requires personalized treatment and preventive measures. In the field of aesthetic medicine, proper regulation of blood flow is crucial for optimal wound healing. This study aims to investigate the prevalence of FS signs and symptoms among individuals seeking aesthetic intervention. Methods A total of 207 patients seeking aesthetic intervention at the Beauty2Go clinic in Lucerne answered a standardized questionnaire consisting of 15 signs and symptoms of FS. Results Overall, 189 (91.3%) patients were female and 18 (8.7%) were male. The mean age was 36.0 years (standard deviation [SD] 12.1) and the median age was 35.0 years (interquartile range [IQR]: 14.0−67.0). Several signs and symptoms of FS were present among patients undergoing aesthetic surgery. Compared to a control group patients showed a higher tendency towards cold hands (25.1% [95% confidence interval [CI]: 19.5–31.7]), feeling cold (21.7% [95% CI: 16.4–28.1]) and low blood pressure (27.3% [95% CI: 21.0–34.7]). Other signs and symptoms included Increased response to certain drugs (8.4% [95% CI: 4.8–14.3]) a low Body Mass Index (BMI) (58.0% [95% CI: 50.9–64.7]), Reversible skin blotches (7.2% [95% CI: 4.3–11.9]) and a tendency towards perfectionism (53.6% [95% CI: 46.6–60.5]). Accompanying symptoms of migraines were lower in the patient group (5.0% [95% CI: 2.2–10.4]) than in the control group. Conclusions The prevalence of FS is notable among individuals seeking aesthetic interventions. Acknowledging this fact not only enables the treatment of FS in patients but also empowers the field of aesthetic medicine to devise proactive strategies for enhancing blood flow regulation through personalized treatment in this population. This research paper emphasizes the significance of identifying FS in the context of aesthetic procedures and highlights the potential benefits of personalized preventive treatments

Super-resolution imaging for the detection of low-energy ion tracks in fine-grained nuclear emulsions

We propose a new wide-field imaging method that exploits the Localized Surface Plasmon Resonance phenomenon to produce super-resolution images with an optical microscope equipped with a custom design polarization analyzer module. In this paper we describe the method and apply it to the analysis of low-energy carbon ion tracks implanted in a nuclear emulsion film. The result is then compared with the measurements of the same tracks carried out at an electronic microscope. The images set side by side show their close similarity. The resolution achieved with the current microscope setup is estimated to be about 50 nm.Comment: 13 pages, 10 figure

Integrated sources of entangled photons at telecom wavelength in femtosecond-laser-written circuits

Photon entanglement is an important state of light that is at the basis of many protocols in photonic quantum technologies, from quantum computing, to simulation and sensing. The capability to generate entangled photons in integrated waveguide sources is particularly advantageous due to the enhanced stability and more efficient light-crystal interaction. Here we realize an integrated optical source of entangled degenerate photons at telecom wavelength, based on the hybrid interfacing of photonic circuits in different materials, all inscribed by femtosecond laser pulses. We show that our source, based on spontaneous parametric down-conversion, gives access to different classes of output states, allowing to switch from path-entangled to polarization-entangled states with net visibilities above 0.92 for all selected combinations of integrated devices

Adaptive phase estimation through a genetic algorithm

Quantum metrology is one of the most relevant applications of quantum information theory to quantum technologies. Here, quantum probes are exploited to overcome classical bounds in the estimation of unknown parameters. In this context, phase estimation, where the unknown parameter is a phase shift between two modes of a quantum system, is a fundamental problem. In practical and realistic applications, it is necessary to devise methods to optimally estimate an unknown phase shift by using a limited number of probes. Here we introduce and experimentally demonstrate a machine learning-based approach for the adaptive estimation of a phase shift in a Mach-Zehnder interferometer, tailored for optimal performances with limited resources. The employed technique is a genetic algorithm used to devise the optimal feedback phases employed during the estimation in an offline fashion. The results show the capability to retrieve the true value of the phase by using few photons, and to reach the sensitivity bounds in such small probe regime. We finally investigate the robustness of the protocol with respect to common experimental errors, showing that the protocol can be adapted to a noisy scenario. Such approach promises to be a useful tool for more complex and general tasks where optimization of feedback parameters is required

Photonic Quantum Metrology

Quantum Metrology is one of the most promising application of quantum technologies. The aim of this research field is the estimation of unknown parameters exploiting quantum resources, whose application can lead to enhanced performances with respect to classical strategies. Several physical quantum systems can be employed to develop quantum sensors, and photonic systems represent ideal probes for a large number of metrological tasks. Here we review the basic concepts behind quantum metrology and then focus on the application of photonic technology for this task, with particular attention to phase estimation. We describe the current state of the art in the field in terms of platforms and quantum resources. Furthermore, we present the research area of multiparameter quantum metrology, where multiple parameters have to be estimated at the same time. We conclude by discussing the current experimental and theoretical challenges, and the open questions towards implementation of photonic quantum sensors with quantum-enhanced performances in the presence of noise.Comment: 51 pages, 9 figures, 967 references. Comments and feedbacks are very welcom

Ambient temperature and kidney function in primary care patients

Introduction Exposure to high ambient temperatures is associated with a risk of acute kidney injury. However, evidence comes from emergency departments or extreme weather exposures. It is unclear whether temperature-related adverse kidney outcomes can also be detected at a community level in a temperate climate zone. Methods In a 9.5-year retrospective cohort study we correlated estimated glomerular filtration rate (eGFR) values of Swiss adult primary care patients from the FIRE cohort (Family medicine Research using Electronic medical records) with same-day maximum local ambient temperature data. We investigated 5 temperature groups (< 15 °C, 15–19 °C, 20–24 °C, 25–29 °C and  ≥ 30 °C) as well as possible interactions for patients with increased kidney vulnerability (chronic heart failure, diabetes, chronic kidney disease, therapy with renin–angiotensin–aldosterone-system (RAAS) inhibitors, diuretics or non-steroidal anti-inflammatory drugs). Results We included 18,000 primary care patients who altogether provided 132,176 creatinine measurements. In the unadjusted analysis, higher ambient temperatures were associated with lower eGFR across all age and vulnerability groups. In the adjusted models, we did not find a consistent association.The highest ambient temperature differences (> 25 or > 30 versus < 15 °C) were associated with marginally reduced kidney function only in patients with ≥ 3 risk factors for kidney vulnerability, with a maximum estimated glomerular filtration rate reduction of −2.9 ml/min/1.73m$^{2}$ (SE 1.0), P 0.003. Discussion In a large primary care cohort from a temperate climate zone, we did not find an association between ambient temperatures and kidney function. A marginal inverse association in highly vulnerable patients is of unclear clinical relevance