Increasing the Astrophysical Reach of the Advanced Virgo Detector via the Application of Squeezed Vacuum States of Light.

Current interferometric gravitational-wave detectors are limited by quantum noise over a wide range of their measurement bandwidth. One method to overcome the quantum limit is the injection of squeezed vacuum states of light into the interferometer's dark port. Here, we report on the successful application of this quantum technology to improve the shot noise limited sensitivity of the Advanced Virgo gravitational-wave detector. A sensitivity enhancement of up to 3.2±0.1 dB beyond the shot noise limit is achieved. This nonclassical improvement corresponds to a 5%-8% increase of the binary neutron star horizon. The squeezing injection was fully automated and over the first 5 months of the third joint LIGO-Virgo observation run O3 squeezing was applied for more than 99% of the science time. During this period several gravitational-wave candidates have been recorded.

2D photonic-crystal optomechanical nanoresonator.

We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8% over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265-nm thick membrane, is used to form a compact microcavity involving the suspended nanomembrane as an end mirror. The resulting cavity has a waist size smaller than 10 µm and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane.

Radiation-pressure cooling and optomechanical instability of a micromirror.

Recent table-top optical interferometry experiments and advances in gravitational-wave detectors have demonstrated the capability of optical interferometry to detect displacements with high sensitivity. Operation at higher powers will be crucial for further sensitivity enhancement, but dynamical effects caused by radiation pressure on the interferometer mirrors must be taken into account, and the appearance of optomechanical instabilities may jeopardize the stable operation of the next generation of interferometers. These instabilities are the result of a nonlinear coupling between the motion of the mirrors and the optical field, which modifies the effective dynamics of the mirror. Such 'optical spring' effects have already been demonstrated for the mechanical damping of an electromagnetic waveguide with a moving wall, the resonance frequency of a specially designed flexure oscillator, and the optomechanical instability of a silica microtoroidal resonator. Here we present an experiment where a micromechanical resonator is used as a mirror in a very high-finesse optical cavity, and its displacements are monitored with unprecedented sensitivity. By detuning the laser frequency with respect to the cavity resonance, we have observed a drastic cooling of the microresonator by intracavity radiation pressure, down to an effective temperature of 10 kelvin. For opposite detuning, efficient heating is observed, as well as a radiation-pressure-induced instability of the resonator. Further experimental progress and cryogenic operation may lead to the experimental observation of the quantum ground state of a micromechanical resonator, either by passive or active cooling techniques.

Backaction amplification and quantum limits in optomechanical measurements.

Optical interferometry is by far the most sensitive displacement measurement technique available, with sensitivities at the 10(-20) m/square root(Hz) level in the large-scale gravitational-wave interferometers currently in operation. Second-generation interferometers will experience a tenfold improvement in sensitivity and be mainly limited by quantum noise, close to the standard quantum limit (SQL), once considered as the ultimate displacement sensitivity achievable by interferometry. In this Letter, we experimentally demonstrate one of the techniques envisioned to go beyond the SQL: amplification of a signal by radiation-pressure backaction in a detuned cavity.

External irradiation for squamous cell carcinoma of the nasal vestibule.

A retrospective analysis of 56 patients who underwent primary external irradiation for squamous cell carcinoma of the nasal vestibule between 1958 and 1983 is presented. The overall 5 year actuarial survival and cause specific survival rates were 64 and 87%, respectively. The 5-year local relapse-free rate after primary irradiation was 80%. Prognostic factors which lowered the local control rate after irradiation included a primary tumor size of 2 cm or more, or involvement of the skin of the ala nasi, columella, lip, cartilage, or bone. Local control was improved in patients who received a tumor dose equivalent to, or greater than, 5500 cGy/25 fractions/5 weeks. Only two patients in whom the primary tumor was controlled developed regional nodal metastases, and elective regional nodal irradiation is not recommended. Four patients (9%) developed significant late morbidity after irradiation. External irradiation is effective treatment for squamous cell carcinoma of the nasal vestibule, and produces high local control and cure rates and good cosmetic results.

Nasopharyngeal angiofibroma: a twenty year study.

A control rate of approximately 80% has been obtained in 45 cases of juvenile nasopharyngeal angiofibroma treated by a single moderate dose of radiotherapy at the Princess Margaret Hospital, Toronto. The remaining patients ultimately achieved control generally after further irradiation. Immediate side-effects of the treatment have been minimal, and no late complications have been observed. In 2-20 years' follow-up, no irradiation-induced tumors have been found. Superiority of irradiation in these cases over surgery is emphasized, as well as the importance of using sophisticated techniques to limit the volume of tissues irradiated and protect vulnerable radiosenstitive structures. Because tumor regression can be expected to continue for many months after treatment has been completed, a policy of observation following radiotherapy is recommended.

Completion thyroidectomy in the management of well-differentiated thyroid carcinoma.

Completion thyroidectomy is the removal of any thyroid tissue that remains after less than total thyroidectomy. At our center, completion thyroidectomy is used when, on permanent sectioning, a frozen section diagnosis is revised from benign to malignant. We reviewed our experience with completion thyroidectomy to examine its indications and complications. We found that the carcinoma was misdiagnosed in 32 of 244 (13%) of cases. Twenty-five of these were initially designated follicular adenomas. The completion proved to be no more technically difficult than a routine hemithyroidectomy. There was one case of permanent hypoparathyroidism (3%). Transient vocal cord palsy occurred in one patient (3%) and transient hypocalcemia occurred in five patients (15%). Complete recovery occurred in all six of these patients. Focal areas of residual carcinoma were found in 8 of 32 (25%) of glands removed at completion. We found completion thyroidectomy to be a safe procedure with minimal morbidity. We recommend its use in those instances of well-differentiated thyroid carcinoma in which the frozen section diagnosis differs from the permanent section.

Xeroradiography in revisional septorhinoplasty.

Because of the continuing increase in the popularity of cosmetic nasal surgery, the revision of previous augmented septorhinoplasties has become more common. With the use of autogenous grafts and the popularization of several synthetic implant materials, a correct preoperative evaluation of the augmented nasal dorsum has become more difficult. Several such patients were examined using conventional soft tissue roentgenograms and xerograms. The latter method produced an improved image of the nasal skeleton when compared with the conventional soft tissue examination. The support for this conclusion is provided by clinical photographs, x-rays films, and xerograms of illustrative cases.

A state observer for the Virgo inverted pendulum.

We report an application of Kalman filtering to the inverted pendulum (IP) of the Virgo gravitational wave interferometer. Using subspace method system identification techniques, we calculated a linear mechanical model of Virgo IP from experimental transfer functions. We then developed a Kalman filter, based on the obtained state space representation, that estimates from open loop time domain data, the state variables of the system. This allows the observation (and eventually control) of every resonance mode of the IP mechanical structure independently.