Optimized generation of spatial qudits by using a pure phase spatial light modulator

We present a method for preparing arbitrary pure states of spatial qudits, namely, D-dimensional (D > 2) quantum systems carrying information in the transverse momentum and position of single photons. For this purpose, a set of D slits with complex transmission are displayed on a spatial light modulator (SLM). In a recent work we have shown a method that requires a single phase-only SLM to control independently the complex coefficients which define the quantum state of dimension D. The amplitude information was codified by introducing phase gratings inside each slit and the phase value of the complex transmission was added to the phase gratings. After a spatial filtering process we obtained in the image plane the desired qudit state. Although this method has proven to be a good alternative to compact the previously reported architectures, it presents some features that could be improved. In this paper we present an alternative scheme to codify the required phase values that minimizes the effects of temporal phase fluctuations associated to the SLM where the codification is carried on. In this scheme the amplitudes are set by appropriate phase gratings addressed at the SLM while the relative phases are obtained by a lateral displacement of these phase gratings. We show that this method improves the quality of the prepared state and provides very high fidelities of preparation for any state. An additional advantage of this scheme is that a complete 2\pi modulation is obtained by shifting the grating by one period, and hence the encoding is not limited by the phase modulation range achieved by the SLM. Numerical simulations, that take into account the phase fluctuations, show high fidelities for thousands of qubit states covering the whole Bloch sphere surface. Similar analysis are performed for qudits with D = 3 and D = 7.Comment: 12 pages, 7 figure

Conditional purity and quantum correlation measures in two qubit mixed states

We analyze and show experimental results of the conditional purity, the quantum discord and other related measures of quantum correlation in mixed two-qubit states constructed from a pair of photons in identical polarization states. The considered states are relevant for the description of spin pair states in interacting spin chains in a transverse magnetic field. We derive clean analytical expressions for the conditional local purity and other correlation measures obtained as a result of a remote local projective measurement, which are fully verified by the experimental results. A simple exact expression for the quantum discord of these states in terms of the maximum conditional purity is also derived.Comment: 16 pages, 5 figures, minor changes, to be published in J. Phys.

Scanning mechanism based on a programmable liquid crystal display

Includes bibliographical references (pages 112-113).In this work we propose a new robust optoelectronic scanning system for scanning microscopy. The device is based on a programmable liquid crystal television display (LCTV) that acts as a pixel-by-pixel controlled pure phase spatial light modulator. The computer addressed liquid crystal screen allows synthesize different diffractive optical elements at video rates. The phase shifts introduced by these elements make possible a complete control over the position and focusing of the scanning beam

Anamorphic zoom system based on liquid crystal displays

In this work we present an anamorphic zoom system, based on liquid crystal displays, which allows changing the magnification and distortion of an image very quickly, without mechanical parts and keeping the output plane stationary. The anamorphic lenses that make up the optical processor are obtained by displaying a combination of convergent-divergent cylindrical lenses, with arbitrary orientations, onto the spatial light modulators. In order to illustrate the capabilities of the system, some experimental results are show

Depth of focus increase by multiplexing programmable diffractive lenses

A combination of several diffractive lenses written onto a single programmable liquid crystal display (LCD) is proposed for increasing the Depth of Focus (DOF) of the imaging system as a whole. The lenses are spatially multiplexed in a random scheme onto the LCD. The axial irradiance distribution produced by each lens overlaps with the next one producing an extended focal depth. To compare the image quality of the multiplexed lenses, the Modulation Transfer Function (MTF) is calculated. Finally we obtain the experimental Point Spread Functions (PSF) for these multiplexed lenses and experimental results in which an extended object is illuminated under spatially incoherent monochromatic light. We compare the images obtained in the focal plane and in some defocused planes with the single lens and with three multiplexed lenses. The experimental results confirm that the multiplexed lenses produce a high increase in the depth of focus.Fil: Iemmi, Claudio Cesar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Campos, Juan. Universitat Autonoma de Barcelona; EspañaFil: Escalera, J. C.. Universitat Autonoma de Barcelona; EspañaFil: López Coronado, O. Universitat Autonoma de Barcelona; EspañaFil: Gimeno, R.. Universitat Autonoma de Barcelona; EspañaFil: Yzuel, María J.. Universitat Autonoma de Barcelona; Españ

Preparing arbitrary pure states of spatial qudits with a single phase-only spatial light modulator

We present a new method for preparing multidimensional spatial qudits by means of a single phase-only spatial light modulator (SLM). This method improves previous ones that use two SLMs, one working in amplitude regime and the other in phase regime. To that end, we addressed diffraction gratings on the slits that define the state and then we performed a spatial filtering in the Fourier plane. The amplitude of the coefficients of the quantum state are determined by the modulation deep of the diffraction gratings, and the relative phase is the mean phase value of the diffraction gratings. This encoding result to be more compact, less expensive and use the photons more efficiently.Instituto de Física La Plat

Preparing arbitrary pure states of spatial qudits with a single phase-only spatial light modulator

We present a new method for preparing multidimensional spatial qudits by means of a single phase-only spatial light modulator (SLM). This method improves previous ones that use two SLMs, one working in amplitude regime and the other in phase regime. To that end, we addressed diffraction gratings on the slits that define the state and then we performed a spatial filtering in the Fourier plane. The amplitude of the coefficients of the quantum state are determined by the modulation deep of the diffraction gratings, and the relative phase is the mean phase value of the diffraction gratings. This encoding result to be more compact, less expensive and use the photons more efficiently.Instituto de Física La Plat

‘I never realised everybody felt as happy as I do when I am around autistic people’: A thematic analysis of autistic adults’ relationships with autistic and neurotypical friends and family

AbstractMany autistic people are motivated to have friends, relationships and close family bonds, despite the clinical characterisation of autism as a condition negatively affecting social interaction. Many first-hand accounts of autistic people describe feelings of comfort and ease specifically with other autistic people. This qualitative research explored and contrasted autistic experiences of spending social time with neurotypical and autistic friends and family. In total, 12 autistic adults (10 females, aged 21–51) completed semi-structured interviews focused on time spent with friends and family; positive and negative aspects of time spent with neurotypical and autistic friends and family; and feelings during and after spending time together. Three themes were identified: cross-neurotype understanding, minority status and belonging. Investigation of these themes reveals the benefits of autistic people creating and maintaining social relationships with other autistic people, in a more systematic way than previous individual reports. They highlight the need for autistic-led social opportunities and indicate benefits of informal peer support for autistic adults.Lay abstractAlthough autistic people may struggle to interact with others, many autistic people have said they find interacting with other autistic people more comfortable. To find out whether this was a common experience, we did hour-long interviews with 12 autistic adults. We asked them questions about how it feels when spending time with their friends and family, and whether it felt different depending on whether the friends and family were autistic or neurotypical. We analysed the interviews and found three common themes in what our participants said. First, they found spending with other autistic people easier and more comfortable than spending time with neurotypical people, and felt they were better understood by other autistic people. Second, autistic people often felt they were in a social minority, and in order to spend time with neurotypical friends and family, they had to conform with what the neurotypical people wanted and were used to. Third, autistic people felt like they belonged with other autistic people and that they could be themselves around them. These findings show that having time with autistic friends and family can be very beneficial for autistic people and played an important role in a happy social life

Elastic Scattering by Deterministic and Random Fractals: Self-Affinity of the Diffraction Spectrum

The diffraction spectrum of coherent waves scattered from fractal supports is calculated exactly. The fractals considered are of the class generated iteratively by successive dilations and translations, and include generalizations of the Cantor set and Sierpinski carpet as special cases. Also randomized versions of these fractals are treated. The general result is that the diffraction intensities obey a strict recursion relation, and become self-affine in the limit of large iteration number, with a self-affinity exponent related directly to the fractal dimension of the scattering object. Applications include neutron scattering, x-rays, optical diffraction, magnetic resonance imaging, electron diffraction, and He scattering, which all display the same universal scaling.Comment: 20 pages, 11 figures. Phys. Rev. E, in press. More info available at http://www.fh.huji.ac.il/~dani