Coincidence imaging is a technique that extracts an image of test system from the statistics photons transmitted by reference when two systems are illuminated source possessing appropriate correlations. It has recently been argued quantum entangled sources necessary for implementation this technique. We show does not require entanglement, and we provide experimental demonstration coincidence using classical source. further find any kind which uses "bucket" detector in arm incapable...

Nonlinear optical phenomena are crucial for a broad range of applications, such as microscopy, all-optical data processing, and quantum information. However, materials usually exhibit weak nonlinearity even under intense coherent illumination. We report that indium tin oxide can acquire an ultrafast large intensity-dependent refractive index in the region spectrum where real part its permittivity vanishes. observe change 0.72 ± 0.025, corresponding to 170% linear index. This is reversible...

We demonstrate a technique for generating tunable all-optical delays in room temperature single-mode optical fibers at telecommunication wavelengths using the stimulated Brillouin scattering process. This makes use of rapid variation refractive index that occurs vicinity gain feature. The wavelength which induced delay is broadly by controlling laser pumping process, and magnitude can be tuned continuously as much 25 ns adjusting intensity pump field. applied to pulses short 15 ns. scheme...

We have observed both superluminal and ultraslow light propagation in an alexandrite crystal at room temperature. Group velocities as slow 91 meters per second to fast -800 were measured attributed the influence of coherent population oscillations involving chromium ions either mirror or inversion sites within lattice. Namely, are inversely saturable cause propagation, whereas experience conventional absorption produce light. This technique for producing large group indices is considerably...

Abstract Light beams with a helical phase-front possess orbital angular momentum along their direction of propagation in addition to the spin that describes polarisation. Until recently, it was thought these two ‘rotational’ motions light were largely independent and could not be coupled during light–matter interactions. However, is now known interactions carefully designed complex media can result spin-to-orbit coupling, where change will modify vice versa . In this work, we propose...

We have observed slow light propagation with a group velocity as low 57.5+/-0.5 m/s at room temperature in ruby crystal. A quantum coherence effect, coherent population oscillations, produces very narrow spectral "hole" the homogeneously broadened absorption profile of ruby. The resulting rapid variation refractive index leads to large value index. observe both for Gaussian-shaped pulses and amplitude modulated optical beams system that is much simpler than those previously used generating light.

Since its introduction 25 years ago, the quantum weak value has gradually transitioned from a theoretical curiosity to practical laboratory tool. While utility is apparent in recent explosion of experiments, interpretation historically been subject confusion. Here pragmatic terms measurable quantities presented, along with an explanation for how it can be determined laboratory. Further, application three distinct experimental techniques reviewed. First, as large interaction parameter amplify...

Entanglement of the properties two separated particles constitutes a fundamental signature quantum mechanics and is key resource for information science. We demonstrate strong Einstein, Podolsky, Rosen correlations between angular position orbital momentum photons created by nonlinear optical process spontaneous parametric down-conversion. The discrete nature continuous but periodic give rise to special sort entanglement these variables. resulting are found be an order magnitude stronger...

We demonstrate that a cancellation of absorption occurs on resonance for two (or any even number of) coupled optical resonators, due to mode splitting and classical destructive interference, particularly when the resonator finesse is large loss in farthest from excitation waveguide small. The linewidth group velocity collection such coupled-resonator structures may be decreased by using larger resonators equal size, unequal size where path length an integer multiple smaller one, or per...

We report on a momentum-position realization of the EPR paradox using direct detection in near and far fields photons emitted by collinear type-II phase-matched parametric down conversion. Using this approach we achieved measured two-photon variance product 0.01 variant Planck's over 2pi (2), which dramatically violates bounds for separability criteria.

Quantum key distribution (QKD) promises information-theoretically secure communication, and is already on the verge of commercialization. Thus far, different QKD protocols have been proposed theoretically implemented experimentally [1, 2]. The next step will be to implement high-dimensional in order improve noise resistance increase data rate [3-7]. Hitherto, no experimental verification single-photon regime has conducted outside laboratory. Here, we report realization such a system...

We describe a theoretical model that shows how stimulated Brillouin scattering (SBS) is initiated by thermally excited acoustic waves distributed within Brillouin-active medium. This predicts the SBS reflectivity, Stokes linewidth, and fluctuations in intensity depend upon laser physical properties of also leads to prediction value single-pass gain (i.e., G=gIL) at threshold for not universal number, but depends frequency on For typical organic liquids room temperature, G range 20--25.

Low-light-level imaging techniques have application in many diverse fields, ranging from biological sciences to security. We demonstrate a single-photon system based on time-gated inten- sified CCD (ICCD) camera which the image of an object can be inferred very few detected photons. show that ghost-imaging configuration, where is obtained photons never interacted with object, useful approach for obtaining images high signal-to-noise ratios. The use heralded single-photons ensures background...

We describe a photonic device based on high-finesse, whispering-gallery-mode disk resonator that can be used for the detection of biological pathogens. This operates by means monitoring change in transfer characteristics when materials fall onto its active area. High sensitivity is achieved because light wave interacts many times with each pathogen as consequence resonant recirculation within structure. Specificity detected substance layer antibodies or other binding material deposited area...

Light with twist and structure Möbius strips are three-dimensional structures consisting of a surface just single side. Readily demonstrated by snipping paper ring, adding twist, then joining the ends together again, these have intriguing mathematical properties in terms topology geometry. Bauer et al. used liquid crystal to engineer wavefront laser beam make an optical version strip effectively “snipping twisting” polarization light beam. Science , this issue p. 964

Coincidence, or ghost, imaging is a technique that uses two correlated optical fields to form an image of object. In this work we identify aspects coincidence which can be performed with classically light sources and require quantum entanglement. We find entangled photons allow high-contrast, high-resolution at any distance from the source. demonstrate fact by forming ghost images in near far photon source, noting product resolutions these factor 3 better than allowed classical diffraction theory.

We present an analysis of four-wave parametric amplification resulting from the nonlinear response a two-level atomic system. The dipole moment induced by weak optical fields at frequencies ${\ensuremath{\omega}}_{3}$ and ${\ensuremath{\omega}}_{4}$ in presence field arbitrary intensity frequency ${\ensuremath{\omega}}_{1}$, where ${\ensuremath{\omega}}_{3}+{\ensuremath{\omega}}_{4}=2{\ensuremath{\omega}}_{1}$, is obtained solving density-matrix equations motion with phenomenological damping...

Quantum key distribution (QKD) systems often rely on polarization of light for encoding, thus limiting the amount information that can be sent per photon and placing tight bounds error rates such a system tolerate. Here we describe proof-of-principle experiment indicates feasibility high-dimensional QKD based transverse structure field allowing transfer more than 1 bit photon. Our implementation uses orbital angular momentum (OAM) photons corresponding mutually unbiased basis position (ANG)....

We describe a method for storing sequences of optical data pulses by converting them into long-lived acoustic excitations in an fiber through the process stimulated Brillouin scattering. These stored can be retrieved later, after time interval limited lifetime excitation. In experiment reported here, smooth 2-nanosecond-long are up to 12 nanoseconds with good readout efficiency: 29% at 4-nanosecond storage and 2% nanoseconds. This thus potentially store packets that many bits long. It...

Plasmonic nanostructures hold promise for the realization of ultra-thin sub-wavelength devices, reducing power operating thresholds and enabling nonlinear optical functionality in metasurfaces. However, this is substantially undercut by absorption introduced resistive losses, causing metasurface community to turn away from plasmonics favour alternative material platforms (e.g., dielectrics) that provide weaker field enhancement, but more tolerable losses. Here, we report a plasmonic with...