Modelling Analytically the Dynamic Response of Thermo-Optic Phase Shifters

Thermo-optic phase shifters are widely adopted to achieve dynamical reconfiguration of integrated waveguide circuits [1], with applications encompassing diverse fields, ranging from free-space beam steering and shaping [2] to quantum information experiments [3]

High-fidelity and polarization-insensitive universal photonic processors fabricated by femtosecond laser writing

Universal photonic processors (UPPs) are fully programmable photonic integrated circuits that are key components in quantum photonics. With this work, we present a novel platform for the realization of low-loss, low-power, and high-fidelity UPPs based on femtosecond laser writing (FLW) and compatible with a large wavelength spectrum. In fact, we demonstrate different UPPs, tailored for operation at 785? nm and 1550? nm, providing similar high-level performances. Moreover, we show that standard calibration techniques applied to FLW-UPPs result in Haar random polarization-insensitive photonic transformations implemented with average amplitude fidelity as high as 0.9979 at 785? nm (0.9970 at 1550? nm), with the possibility of increasing the fidelity over 0.9990 thanks to novel optimization algorithms. Besides being the first demonstrations of polarization-insensitive UPPs, these devices show the highest level of control and reconfigurability ever reported for a FLW circuit. These qualities will be greatly beneficial to applications in quantum information processing

Universal photonic processors in a glass-based femtosecond laser writing platform

Femtosecond laser writing (FLW) can open new perspectives on universal photonic processors (UPPs). We propose here two building blocks for the realization of FLW-UPPs and we show the preliminary results obtained on a 6-mode device

Idiopathic pulmonary fibrosis telemedicine management during COVID-19 outbreak

The present report investigates the impact of a Telemedicine Service (TMS) on the management of Idiopathic Pulmonary Fibrosis (IPF) during coronavirus disease of 2019 (COVID-19) outbreak in Italy. The TMS comprised 3 phone numbers, active 12 h per day, and an email address, monitored every 4 h by trained physicians; chat-and videoconference-services were also offered. At the end of the study period, our staff contacted all patients, to get information about the final outcome (i.e. composite hospitalisations/all causes of death). Outcomes were compared with a cohort of patients who attended our unit in the same period of the previous year (when no TMS was available). 189 patients participated in the present study. From 11th March to 4th May 2020, 61% of patients made at least one TMS access, mostly by emails (53%), followed by phone calls (33%). With regard to the primary outcome, TMS patients experienced a significant lower rate of events of the 182 patients of the no-TMS cohort (p < 0.001). Specifically, a significant difference was observed for IPF hospitalisation (p < 0.001) whereas no differences were observed with regard to deaths (p = 0.64). TMS permits patients to be followed up even during COVID-19 lockdown, with an encouraging impact on outcomes

Universal photonic processors fabricated by femtosecond laser writing

Universal photonic processors (UPPs) are reconfigurable photonic integrated circuits able to implement arbitrary unitary transformations on an input photonic state. Femtosecond laser writing (FLW) allows for rapid and cost-effective fabrication of circuits with low propagation losses. A FLW process featuring thermal isolation allows for a dramatic reduction in dissipated power and crosstalk in integrated thermally-reconfigurable Mach-Zehnder interferometers (MZIs), especially when operated in vacuum, with 0.9 mW dissipation for full reconfiguration and 0.5% crosstalk at 785 nm wavelength. To demonstrate the potential of this technology we fabricated and characterized a 6-mode FLW-UPP in a rectangular MZI mesh with 30 thermal shifters

Experimental certification of contextuality, coherence, and dimension in a programmable universal photonic processor

Quantum superposition of high-dimensional states enables both computational speed-up and security in cryptographic protocols. However, the exponential complexity of tomographic processes makes certification of these properties a challenging task. In this work, we experimentally certify coherence witnesses tailored for quantum systems of increasing dimension using pairwise overlap measurements enabled by a six-mode universal photonic processor fabricated with a femtosecond laser writing technology. In particular, we show the effectiveness of the proposed coherence and dimension witnesses for qudits of dimensions up to 5. We also demonstrate advantage in a quantum interrogation task and show it is fueled by quantum contextuality. Our experimental results testify to the efficiency of this approach for the certification of quantum properties in programmable integrated photonic platforms

Efficacy and durability of multifactorial intervention on mortality and MACEs:a randomized clinical trial in type-2 diabetic kidney disease

Background: Multiple modifiable risk factors for late complications in patients with diabetic kidney disease (DKD), including hyperglycemia, hypertension and dyslipidemia, increase the risk of a poor outcome. DKD is associated with a very high cardiovascular risk, which requires simultaneous treatment of these risk factors by implementing an intensified multifactorial treatment approach. However, the efficacy of a multifactorial intervention on major fatal/non-fatal cardiovascular events (MACEs) in DKD patients has been poorly investigated. Methods: Nephropathy in Diabetes type 2 (NID-2) study is a multicentre, cluster-randomized, open-label clinical trial enrolling 395 DKD patients with albuminuria, diabetic retinopathy (DR) and negative history of CV events in 14 Italian diabetology clinics. Centres were randomly assigned to either Standard-of-Care (SoC) (n = 188) or multifactorial intensive therapy (MT, n = 207) of main cardiovascular risk factors (blood pressure 40/50 mg/dL for men/women and < 175 mg/dL, respectively). Primary endpoint was MACEs occurrence by end of follow-up phase. Secondary endpoints included single components of primary endpoint and all-cause death. Results: At the end of intervention period (median 3.84 and 3.40 years in MT and SoC group, respectively), targets achievement was significantly higher in MT. During 13.0 years (IQR 12.4–13.3) of follow-up, 262 MACEs were recorded (116 in MT vs. 146 in SoC). The adjusted Cox shared-frailty model demonstrated 53% lower risk of MACEs in MT arm (adjusted HR 0.47, 95%CI 0.30–0.74, P = 0.001). Similarly, all-cause death risk was 47% lower (adjusted HR 0.53, 95%CI 0.29–0.93, P = 0.027). Conclusion: MT induces a remarkable benefit on the risk of MACEs and mortality in high-risk DKD patients. Clinical Trial Registration ClinicalTrials.gov number, NCT00535925. https://clinicaltrials.gov/ct2/show/NCT0053592

Analytical modeling of the static and dynamic response of thermally actuated optical waveguide circuits

Thermo-optic phase shifters allow one to dynamically tune and control the operation of integrated-optics interferometers. They have been demonstrated nowadays in different waveguide platforms, and their reliable functioning has enabled the realization of reconfigurable circuits of notable complexity. The design approach to such devices is often based on finite-element numerical simulations, which provide accurate descriptions of the underlying thermal phenomena, at the price of long computational times. Here, on the contrary, we devise an analytical model for the heat diffusion in a simplified geometrical configuration. The model describes both static and dynamic regimes, and can be conveniently applied both to three-dimensional waveguide devices inscribed by femtosecond laser pulses and to planar lithographic circuits. The accuracy of the predictions of the model is validated with experimental measurements on Mach-Zehnder interferometers with different geometries, realized in both kinds of platforms

Low Power Reconfigurability and Reduced Crosstalk in Integrated Photonic Circuits Fabricated by Femtosecond Laser Micromachining

Femtosecond laser writing is a powerful technique that allows rapid and cost-effective fabrication of photonic integrated circuits with unique 3D geometries. In particular, the possibility to reconfigure such devices by thermo-optic phase shifters represents a paramount feature, exploited to produce adaptive and programmable circuits. However, the scalability is strongly limited by the flaws of current thermal phase shifters, which require hundreds of milliwatts to operate and exhibit large thermal crosstalk. In this work, thermally-insulating 3D microstructures are exploited to decrease the power needed to induce a 2π phase shift down to 37&nbsp;mW and to reduce the crosstalk to a few percent. Further improvement is demonstrated when operating in vacuum, with sub-milliwatt power dissipation and negligible crosstalk. These results pave the way toward the demonstration of complex programmable integrated photonic circuits fabricated by femtosecond laser writing, thus opening exciting perspectives in integrated quantum photonics