Menlo Systems’ Post

Fig. 5: Advanced optical technique assisting structured light multiplexing. a A perfect optical system and an aberrated system, as well as vectorial-AO-enhanced optical system. b Electrically tunable disclination line—visualisation of the movement of different topological defect states under different control voltages. c Metasurface-based techniques for complex beam multiplexing https://lnkd.in/gqEtSXtC

The polarization of a light beam gives rise to multiple phenomena and as many interpretations Good morning, In this post I will avoid confusing the polarization which produces polarized light and that which is associated with the electric field propagating in one direction. Polarized light is the basis of optical experiments such as Newton's rings, multi-colored areas, developing around the point of contact of a hemispherical lens with a plane support: quarter-wave or half-wave plates, bottom rotate the plane of polarization proportionally to the thickness of the blade so that by skilfully crossing two blades, we can modify the transparency of the whole; it is the law of Malus. Polarized light associated with the electric field of an electromagnetic wave is present in radioelectricity courses and the ground wave of an antenna can be received in horizontal or vertical polarization of the receiving antenna, and it goes without saying that reception is optimal when the antennas are aligned in polarization. The interpretation of these experiments gives rise to a formatting, for example, in the radio experiment, the polarization is closely linked to the propagation and to the Fresnel or Fraunhofer zones describing it, that is to say -say the distance from the observer to a “source point”, related to a wavelength. Diffraction appears for wavelengths a factor of 10 or 20 less than the distance of the zone. In direct view, propagation will be better and it is in the band of a few GHz that radio beams develop. Otherwise, we seek to optimize the path of the wave through reflections or repeaters. I can only recommend reading the book « Optique » of the course by G. Bruhat with a preface by A. Kastler (Masson, 1954 for example) to refine the notions of Optics linked to polarization in white light (fluted spectrum). But I mention here the thin reading lens making it possible to magnify the field observed from a zoned Fresnel lens: in white light, there would be, at least from a certain wavelength of the spectrum, appearance of iridescence and rainbow effects. Attached photo with domestic lighting. Good reception, thank you for any comments Eric Umdenstock

New virtual particles could be clearly signalled by a right-handed contribution to the photon polarization This result showcases the exceptional capability of the LHCb experiment to study b → sγ transitions. The uncertainty is currently dominated by the data sample size, and thus more accurate studies are foreseen with the large data sample expected in Run 3 of the LHC. More precise measurements may yet unravel a small right-handed polarisation. https://lnkd.in/gVnwfqGe

A very nice treatise from UNM on microwave phase noise, and how it affects high-performance NV-diamond quantum sensing at the picotesla level. https://lnkd.in/ecX3Z5z5

*new paper* These results are so exciting that I had to break my tradition of not submitting to preprint journals. The story for this work goes back to 2018 when I was lying next to the pool looking up at a clear sky (clearly not Scotland) through polarisation sunglasses. Tilting my head, I realised I never appreciated just how polarised the scattered reflection was; it is a strange phenomenon like that that stays in your mind. Fast forward to 2021/22 in the lab where my team are developing and demonstrating multimode free-space interferometer optical receivers for time- and phase-based quantum communication protocols with satellite application in mind. Traditionally, that area has been dominated by polarisation-based protocols due to the robustness of the encoding to atmospheric impacts, so polarisation filtering of the background noise wasn't ever considered. However, time- and phase-based protocols only require a single linear polarisation, thus polarisation filtering can be applied. In a previous paper, we showed a 3dB improvement to the signal-to-noise for time- and phase-based protocols but filtering with unpolarised white-light background. However, with the background scattered light from the sky partially polarised (depending on the wavelength, position in the sky, and the sun's position as well), that signal-to-noise ratio could be improved further, allowing us to perform satellite-to-ground quantum communications with more noise, pushing us towards the daytime operation. The paper is simulation-based and highlights the difference between applying and not applying the polarisation filtering mechanism at dawn and dusk. Here it is: https://lnkd.in/eBuvGvKE Note: Clouds and other obscurants cause the scatter to be unpolarised, negating any benefit in aiding quantum communications through obscurants. The simulation tool used was Qrackling: https://lnkd.in/d4AX52Gj #quantum #quantumtechnology #quantumspace #satellite

What Is O-PTIR? The O-PTIR technique overcomes the IR diffraction limit associated with traditional IR microscopy techniques by illuminating the sample with a mid-IR pulsed tunable quantum cascade laser (QCL) and measuring infrared absorption indirectly with a visible laser beam. When the QCL laser is tuned to a wavelength that excites molecular vibrations in the sample, absorption occurs, creating photothermal effects, e.g., sample surface expansion and a change in refractive index. The visible probe laser, focused to a sub-micron spot size, measures this photothermal response via a modulation induced in the scattered light, as shown in the video. The IR laser can be swept through the entire range in under two seconds to obtain an IR spectrum. @photothermalspectroscopy

Now published in @PRXQuantum: Our work on engineered nonlinearities and controllable pair-hopping processes in optics and quantum gases !

Optimum quantum detection - key is the density operator rho that captures the signal and noise model. To me it is truly analogous to the covariance matrix which plays a role in so many classical detection problems. In the simplest case , its just |phi><phi| where |phi> is the wavefunction describing the signal. But more generally with composite signals and noise, it s a matrix of terms, with on diagonal terms, rho_ii = |phi_i><phi_i|, describing the probability or strength of the i-th component. Its the off diagonal terms, rho_ij = |phi_i><phi_j|, that may hold the most interest in signal processing because its here that the coherence between components is modelled. Coherence due to the photons being from the same laser would be captured here. Less than ideal performance in a quantum computer’s generation of cubits can also be reflected in weaker off diagonal terms.