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We designed and built a novel model of a deployed space telescope which can reliably align its segments to achieve the finest possible resolution. An asymmetric design of both the segment shapes and their pupil locations were tested in simulation and experiment. We optimised the sparse aperture for better spatial frequency coverage and for smoother images with less artifacts. The unique segment shapes allow for an easier identification and alignment, and the feedback is based only upon the focal image. The autonomous alignment and fine tuning are governed by mechanical simplicity and reliability., Comment: 10 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1912.00709

Heisenberg's uncertainty principle tells us that it is impossible to determine simultaneously the position of a photon crossing a telescope's aperture and its momentum. Super-resolution imaging techniques rely on modification of the observed sample, or on entangling photons. In astronomy we have no access to the object, but resolution may be improved by optical amplification. Unfortunately, spontaneous emission contributes noise and negates the possible gain from stimulated emissions. We show that it is possible to increase the weight of the stimulated photons by considering photon statistics, and observe an improvement in resolution. Most importantly, we demonstrate a method which can apply for all imaging purposes., Comment: Accepted for publications in the Journal of the Optical Society of America B Special Issue on Astrophotonics

After launching and deploying a sparse space telescope, fine tuning is required to correct for inaccurate initial placement of its elements. We selected unique shapes and locations of these telescope aperture segments, to be able to distinguish between their diffraction patterns, while at the same time having a proper spatial frequency coverage. Then we improved the combined wave front, without measuring it directly: First we correlated each segment's focal image with its distinctive template, to correct its tilt. Next we interfered them with the other segments, pair by pair, using their limited coherence, to locate their mutual optical path differences. Finally, we optimized the combined focal image for fine alignment., Comment: 5 pages, 6 figures

Evidence of exoplanets with orbits that are misaligned with the spin of the host star may suggest that not all bound planets were born in the protoplanetary disk of their current planetary system. Observations have shown that free-floating Jupiter-mass objects can exceed the number of stars in our galaxy, implying that capture scenarios may not be so rare. To address this issue, we construct a three-dimensional simulation of a three-body scattering between a free-floating planet and a star accompanied by a Jupiter-mass bound planet. We distinguish between three different possible scattering outcomes, where the free-floating planet may get captured after the interaction with the binary, remain unbound, or "kick-out" the bound planet and replace it. The simulation was performed for different masses of the free-floating planets and stars, as well as different impact parameters, inclination angles and approach velocities. The outcome statistics are used to construct an analytical approximation of the cross section for capturing a free-floating planet by fitting their dependence on the tested variables. The analytically approximated cross section is used to predict the capture rate for these kinds of objects, and to estimate that about 1\% of all stars are expected to experience a temporary capture of a free-floating planet during their lifetime. Finally, we propose additional physical processes that may increase the capture statistics and whose contribution should be considered in future simulations., Comment: The paper was submitted to MNRAS last week using their template. For this version no template was used, but the content is exactly the same

In a previous article we suggested a method to overcome the diffraction limit behind a telescope. We refer to theory and recent numerical simulations, and test whether it is indeed possible to use photon amplification to enhance the angular resolution of a telescope or a microscope beyond the diffraction limit. An essential addition is the proposal to select events with above-average ratio of stimulated to spontaneous photons. We find that the diffraction limit of a telescope is surpassed by a factor ten for an amplifier gain of 200, if the analysis is restricted to a tenth of the incoming astronomical photons. A gain of 70 is sufficient with a hundredth of the photons., Comment: Accepted for publication in Optics Letters

Being able to image the human retina in high resolution opens a new era in many important fields, such as pharmacological research for retinal diseases, researches in human cognition, nervous system, metabolism and blood stream, to name a few. In this paper, we propose to share the knowledge acquired in the fields of optics and imaging in solar astrophysics in order to improve the retinal imaging at very high spatial resolution in the perspective to perform a medical diagnosis. The main purpose would be to assist health care practitioners by enhancing retinal images and detect abnormal features. We apply a nonlinear registration method using local correlation tracking to increase the field of view and follow structure evolutions using correlation techniques borrowed from solar astronomy technique expertise. Another purpose is to define the tracer of movements after analyzing local correlations to follow the proper motions of an image from one moment to another, such as changes in optical flows that would be of high interest in a medical diagnosis., Comment: 21 pages, 7 figures, submitted to Optics Communications

An Earth-like extra-solar planet emits light which is many orders of magnitude fainter than that of the parent star. We propose a method of identifying bio-signature spectral lines in light from known extra-solar planets based on Fourier spectroscopy in the infra-red, using an off-center part of a Fourier interferogram only. This results in superior sensitivity to narrower molecular-type spectral bands, which are expected in the planet spectrum but are absent in the parent star. We support this idea by numerical simulations which include photon and thermal noise, and show it to be feasible at a luminosity ratio of 10^-6 for a Sun-like parent star in the infra-red. We also carried out a laboratory experiment to illustrate the method. The results suggest that this method should be applicable to real planet searches.

Imaging of planets is very difficult, due to the glare from their nearby, much brighter suns. Static and slowly-evolving aberrations are the limiting factors, even after application of adaptive optics. The residual speckle pattern is highly symmetrical due to diffraction from the telescope's aperture. We suggest to break this symmetry and thus to locate planets hidden beneath it. An eccentric pupil mask is rotated to modulate the residual light pattern not removed by other means. This modulation is then exploited to reveal the planet's constant signal. In well-corrected ground-based observations we can reach planets six stellar magnitudes fainter than their sun, and only 2-3 times the diffraction limit from it. At ten times the diffraction limit, we detect planets 16 magnitudes fainter. The stellar background drops by five magnitudes., Comment: Accepted for publication in Optics Express

The aim of this paper is to revisit the implications of complementarity when we inject into a Mach Zehnder interferometer particles with internal structure, prepared in special translational-internal entangled (TIE) states. This correlation causes the path distinguishability to be phase dependent in contrast to the standard case. We show that such a TIE state permits us to detect small phase shifts along with almost perfect path distinguishability, beyond the constraints imposed by complementarity on simultaneous which-way and which-phase measurements for standard cases (when distinguishability is independent of interferometric phase)., Comment: 14 pages, 5 figures

Stellar amplitude interferometry is limited by the need to have optical distances fixed and known to a fraction of the wavelength. We suggest reviving intensity interferometry, which requires hardware which is many orders of magnitude less accurate, at the cost of more limited sensitivity. We present an algorithm to use the very high redundancy of a uniform linear array to increase the sensitivity of the instrument by more than a hundredfold. When using an array of 100 elements, each almost 100m in diameter, and conservative technological improvements, we can achieve a limiting magnitude of about mb=14.4. Digitization, storage, and off-line processing of all the data will also enable interferometric image reconstruction from a single observation run, and application of various algorithms at any later time. Coronagraphy, selectively suppressing only the large scale structure of the source, can be achieved by specific aperture shapes. We conclude that after three decades of abandonment optical intensity interferometry deserves another review., Comment: The article has been accepted for publication in MNRAS

Intensity interferometry removes the stringent requirements on mechanical precision and atmospheric corrections that plague all amplitude interferometry techniques at the cost of severely limited sensitivity. A new idea we recently introduced, very high redundancy, alleviates this problem. It enables the relatively simple construction (~1cm mechanical precision) of a ground-based astronomical facility able to transform a two-dimensional field of point-like sources to a three-dimensional distribution of micro-arcsec resolved systems, each imaged in several optical bands. Each system will also have its high resolution residual timing, high quality (inside each band) spectra and light curve, emergent flux, effective temperature, polarization effects and perhaps some thermodynamic properties, all directly measured. All the above attributes can be measured in a single observation run of such a dedicated facility. We conclude that after three decades of abandonment optical intensity interferometry deserves another review, also as a ground-based alternative to the science goals of space interferometers., Comment: The article has been accepted for publication in MNRAS

A dialog with Asher Peres regarding the meaning of quantum teleportation is briefly reviewed. The Braunstein-Kimble method for teleportation of light is analyzed in the language of quantum wave functions. A pictorial example of continuous variable teleportation is presented using computer simulation., Comment: 11 pages, 8 figures