Programmable optical waveform reshaping on a picosecond timescale

We experimentally demonstrate temporal reshaping of optical waveforms in the telecom wavelength band using the principle of quantum frequency conversion. The reshaped optical pulses do not undergo any wavelength translation. The interaction takes place in a nonlinear $\chi^{(2)}$ waveguide using an appropriately designed pump pulse programmed via an optical waveform generator. We show reshaping of a single-peak pulse into a double-peak pulse and vice versa. We also show that exponentially decaying pulses can be reshaped into near Gaussian shape, and vice versa, which is a useful functionality for quantum communications.Comment: Manuscript updated after comments from reviewers. Journal reference and DOI also adde

Designing Noise-Robust Quantum Networks Coexisting in the Classical Fiber Infrastructure

The scalability of quantum networking will benefit from quantum and classical communications coexisting in shared fibers, the main challenge being spontaneous Raman scattering noise. We investigate the coexistence of multi-channel O-band quantum and C-band classical communications. We characterize multiple narrowband entangled photon pair channels across 1282 nm-1318 nm co-propagating over 48 km installed standard fiber with record C-band power (>18 dBm) and demonstrate that some quantum-classical wavelength combinations significantly outperform others. We analyze the Raman noise spectrum, optimal wavelength engineering, multi-photon pair emission in entangled photon-classical coexistence, and evaluate the implications for future quantum applications

Quantum-noise--randomized data-encryption for WDM fiber-optic networks

We demonstrate high-rate randomized data-encryption through optical fibers using the inherent quantum-measurement noise of coherent states of light. Specifically, we demonstrate 650Mbps data encryption through a 10Gbps data-bearing, in-line amplified 200km-long line. In our protocol, legitimate users (who share a short secret-key) communicate using an M-ry signal set while an attacker (who does not share the secret key) is forced to contend with the fundamental and irreducible quantum-measurement noise of coherent states. Implementations of our protocol using both polarization-encoded signal sets as well as polarization-insensitive phase-keyed signal sets are experimentally and theoretically evaluated. Different from the performance criteria for the cryptographic objective of key generation (quantum key-generation), one possible set of performance criteria for the cryptographic objective of data encryption is established and carefully considered.Comment: Version 2: Some errors have been corrected and arguments refined. To appear in Physical Review A. Version 3: Minor corrections to version

Is There a Patient Profile That Characterizes a Patient With Adult Spinal Deformity as a Candidate for Minimally Invasive Surgery?

Study designRetrospective review.ObjectivesThe goal of this study was to evaluate the baseline characteristics of patients chosen to undergo traditional open versus minimally invasive surgery (MIS) for adult spinal deformity (ASD).MethodsA multicenter review of 2 databases including ASD patients treated with surgery. Inclusion criteria were age >45 years, Cobb angle minimum of 20°, and minimum 2-year follow-up. Preoperative radiographic parameters and disability outcome measures were reviewed.ResultsA total of 350 patients were identified: 173 OPEN patients and 177 MIS. OPEN patients were significantly younger than MIS patients (61.5 years vs 63.74 years, P = .013). The OPEN group had significantly more females (87% vs 76%, P = .006), but both groups had similar body mass index. Preoperative lumbar Cobb was significantly higher for the OPEN group (34.2°) than for the MIS group (26.0°, P < .001). The mean preoperative Oswestry Disability Index was significantly higher in the MIS group (44.8 in OPEN patients and 49.8 in MIS patients, P < .011). The preoperative Numerical Rating Scale value for back pain was 7.2 in the OPEN group and 6.8 in the MIS group preoperatively, P = .100.ConclusionsPatients chosen for MIS for ASD are slightly older and have smaller coronal deformities than those chosen for open techniques, but they did not have a substantially lesser degree of sagittal malalignment. MIS surgery was most frequently utilized for patients with an sagittal vertical axis under 6 cm and a baseline pelvic incidence and lumbar lordosis mismatch under 30°

Early and Late Reoperation Rates With Various MIS Techniques for Adult Spinal Deformity Correction.

Study designA multicenter retrospective review of an adult spinal deformity database.ObjectiveWe aimed to characterize reoperation rates and etiologies of adult spinal deformity surgery with circumferential minimally invasive surgery (cMIS) and hybrid (HYB) techniques.MethodsInclusion criteria were age ≥18 years, and one of the following: coronal Cobb >20°, sagittal vertical axis >5 cm, pelvic tilt >20°, and pelvic incidence-lumbar lordosis >10°. Patients with either cMIS or HYB surgery, ≥3 spinal levels treated with 2-year minimum follow-up were included.ResultsA total of 133 patients met inclusion for this study (65 HYB and 68 cMIS). Junctional failure (13.8%) was the most common reason for reoperation in the HYB group, while fixation failure was the most common reason in the cMIS group (14.7%). There was a higher incidence of proximal junctional failure (PJF) than distal junctional failure (DJF) within HYB (12.3% vs 3.1%), but no significant differences in PJF or DJF rates when compared to cMIS. Early (<30 days) reoperations were less common (cMIS = 1.5%; HYB = 6.1%) than late (>30 days) reoperations (cMIS = 26.5%; HYB = 27.7%), but early reoperations were more common in the HYB group after propensity matching, largely due to infection rates (10.8% vs 0%, P = .04).ConclusionsAdult spinal deformity correction with cMIS and HYB techniques result in overall reoperation rates of 27.9% and 33.8%, respectively, at minimum 2-year follow-up. Junctional failures are more common after HYB approaches, while pseudarthrosis/fixation failures happen more often with cMIS techniques. Early reoperations were less common than later returns to the operating room in both groups, but cMIS demonstrated less risk of infection and early reoperation when compared with the HYB group

Treatment of the Fractional Curve of Adult Scoliosis With Circumferential Minimally Invasive Surgery Versus Traditional, Open Surgery: An Analysis of Surgical Outcomes.

Study Design:Retrospective, multicenter review of adult scoliosis patients with minimum 2-year follow-up. Objective:Because the fractional curve (FC) of adult scoliosis can cause radiculopathy, we evaluated patients treated with either circumferential minimally invasive surgery (cMIS) or open surgery. Methods:A multicenter retrospective adult deformity review was performed. Patients included: age >18 years with FC >10°, ≥3 levels of instrumentation, 2-year follow-up, and one of the following: coronal Cobb angle (CCA) > 20°, pelvic incidence and lumbar lordosis (PI-LL) > 10°, pelvic tilt (PT) > 20°, and sagittal vertical axis (SVA) > 5 cm. Results:The FC was treated in 118 patients, 79 open and 39 cMIS. The FCs had similar coronal Cobb angles preoperative (17° cMIS, 19.6° open) and postoperative (7° cMIS, 8.1° open), but open had more levels treated (12.1 vs 5.7). cMIS patients had greater reduction in VAS leg (6.4 to 1.8) than open (4.3 to 2.5). With propensity matching 40 patients for levels treated (cMIS: 6.6 levels, N = 20; open: 7.3 levels, N = 20), both groups had similar FC correction (18° in both preoperative, 6.9° in cMIS and 8.5° postoperative). Open had more posterior decompressions (80% vs 22.2%, P < .001). Both groups had similar preoperative (Visual Analogue Scale [VAS] leg 6.1 cMIS and 5.4 open) and postoperative (VAS leg 1.6 cMIS and 3.1 open) leg pain. All cMIS patients had interbody grafts; 35% of open did. There was no difference in change of primary CCA, PI-LL, LL, Oswestry Disability Index, or VAS Back. Conclusion:Patients' FCs treated with cMIS had comparable reduction of leg pain compared with those treated with open surgery, despite significantly fewer cMIS patients undergoing direct decompression

Appointments, pay and performance in UK boardrooms by gender

This article uses UK data to examine issues regarding the scarcity of women in boardroom positions. The article examines appointments, pay and any associated productivity effects deriving from increased diversity. Evidence of gender-bias in the appointment of women as non-executive directors is found together with mixed evidence of discrimination in wages or fees paid. However, the article finds no support for the argument that gender diverse boards enhance corporate performance. Proposals in favour of greater board diversity may be best structured around the moral value of diversity, rather than with reference to an expectation of improved company performance