Physical Optics Corporation

Quantum correlated states of light, such as squeezed states, are a fundamental resource for the development of quantum technologies, as they are needed for applications in quantum metrology, quantum computation, and quantum communications. It is thus critical to develop compact, efficient, and robust sources to generate such states. Here, we report on a compact, narrowband, fiber-coupled source of two-mode squeezed states of light at 795 nm based on four-wave mixing (FWM) in an 85Rb atomic vapor. The source is designed in a small modular form factor, with two input fiber-coupled beams, the seed and pump beams required for the FWM, and two output fibers, one for each of the modes of the squeezed state. The system is optimized for low pump power (135 mW) to achieve a maximum intensity-difference squeezing of 4.4 dB after the output of fibers at an analysis frequency of 1 MHz. The narrowband nature of the source makes it ideal for atomic-based quantum sensing and quantum networking configurations that rely on atomic quantum memories. Such a source paves the way for a versatile and portable platform for applications in quantum information science.

Michael Bentley weighs up the cost and benefits of infection control in a changing dental environment

The power conversion efficiency of the proton-conductive thermoelectric cell is improved by the unidirectional orientation of ionic conductivity in the electrospun Nafion cell. The thermoelectric performance of nanofibers is experimentally demonstrated.

The appearance of non-blood cells circulating in human peripheral bloodstream indicates an abnormal condition. One important category of these cells is circulating endothelial cells (CECs) shed by compromised blood vessels. Clinical applications that measure the blood level of CECs are hindered due to a lack of standardized instruments. The major challenge in detecting circulating non-blood cells is their extreme scarcity; 1 in 106 to 107. Described here is a new method for detection of rare cells in blood samples deposited on the adhesive microscopic slides and immunostained with distinct fluorescent markers. The key novelty of the proposed approach is an intelligent search principle and a dual-mode scanner to implement this principle. To begin, a fast scanning that uses a single beam is performed in the spectral channel where only rare cells produce florescence. Once a target cell is registered, the scanner switches on the imaging mode, auto-focuses and then records images in multiple spectral channels at the selected area. The instrument runs in repetitive cycles until the entire slide is scanned. The technology has been validated via detection of human umbilical vein endothelial cells spiked into human blood samples. In addition, the operational principle can be adapted for detection of other types of rare cells in blood.

To improve the resolution and field of view of high-energy Compton-scattered x-ray and gamma-ray imaging systems, we have developed and tested apodized imaging optics based on apertures with depth-dependent cross sections fabricated in an x-ray-absorbing material. Through ray-tracing modeling, we determined the optimum aperture shapes (apodizations) that maximize the field of view and/or resolution of the system. Such apodized apertures can be used either in single-aperture optics, or in coded-aperture arrays. Potential applications of this technology include nondestructive evaluation (NDE) of materials and structures, in particular Compton imaging tomography (CIT), x-ray and gamma-ray astronomy, and medical imaging.

In this paper we discuss a rather surprising result of Bayesian inference analysis: performance of a broad variety of sensors depends not only on a sensor system itself, but also on CONOPS parameters in such a way that even an excellent sensor system can perform poorly if absolute probabilities of a threat (target) are lower than a false alarm probability. This result, which we call <i>Bayesian paradox</i>, holds not only for binary sensors as discussed in the lead author's previous papers, but also for a more general class of multi-target sensors, discussed also in this paper. Examples include: ATR (automatic target recognition), luggage X-ray inspection for explosives, medical diagnostics, car engine diagnostics, judicial decisions, and many other issues.

The authors present the design and experimental results of a meta-material multilayered structure in a two-dimensional (2-D) matrix described by Torrent and Sánchez-Dehesa (2007) which can be applied to the fabrication of acoustic lenses and cloaks by tailoring the material anisotropy. The structure consists of a 2-D matrix made of two isotropic materials (low-density foam and aluminum) that are evenly spaced in air with varying diameters in order to control the acoustic impedance. We simulated a 2-D matrix in order to design an acoustic lens with a focal length of 18 cm and a gain of 13 dB in a finite element analysis program. Based on these simulation results, we designed and fabricated a 2-D acoustic lens. We measured the properties of the acoustic lens, having a focal length of 17 cm and a focal point gain of 14 dB (re 20 μPa). The excellent agreement between the simulation and experimental results supports the use of a 2-D meta-material structure for the control of acoustic signals in any arbitrary application and can be used for the design of more complex structures in the future.

Image intensifier tubes, as part of night vision devices, have been the primary devices for the detection and amplification of near infrared light for night vision operations. In this paper, we demonstrate a novel all-optical night vision amplifier device with a potential to replace the image intensifier tube in night vision goggles. This image amplifier is based on a novel structure of semiconductor and spectrally tunable liquid crystal (LC) materials within a thin cell. The LC reacts to near-infrared (NIR) radiation but is unaffected by visible light, allowing see-through capability including visible-wavelength cockpit light. The technology is made very attractive by its high sensitivity, spatial resolution, and contrast without expensive, bulky, and heavy optics or high-voltage components.

Active noise reduction (ANR) for aircrew hearing protection in harsh noise environments such as military and civilian flight operations requires a high‐performance, microsized driver that provides not only high acoustic power, at least 130 dB SPL, but also high fidelity sound quality, especially in low‐frequency ranges below 100 Hz. A new microsized smart material actuator (MSMA) is being developed by using high‐density and direct‐conversion piezoelectric exciters combined with a unique acoustic structure, unlike conventional moving coil/magnet‐type drivers. The dimensions of the MSMA are 6 mm in diameter by 7 mm long, small enough for ear‐canal application as an earplug driver, maximizing ANR effectiveness. The MSMA system consists of a microscale earplug driver, a protective package made of medical‐grade stainless steel, and a compact actuation amplifier easily connected to or embedded in an external ANR controller. Performance tests show the system produces over 130 dB SPL in a 1 cc trapped cylindrical volume with very flat frequency responses even below 100 Hz. The total harmonic distortion of the MSMA is lower than 4% over all audible frequency ranges, without phase delay or discontinuities.