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...

Quantum communication has been successfully implemented in optical fibres and through free-space.Fibre systems, though capable of fast key low error rates, are impractical communicating with destinations without an established fibre link.Free-space quantum channels can overcome such limitations reach long distances the advent satellite-toground links.However, turbulence, resulting from local fluctuations refractive index, becomes a major challenge by adding errors losses.Recently, interest...

Imaging photoelectron photoion coincidence spectroscopy was employed to explore the unimolecular dissociation of ionized polycyclic aromatic hydrocarbons (PAHs) acenaphthylene, fluorene, cyclopenta[d,e,f]phenanthrene, pyrene, perylene, fluoranthene, dibenzo[a,e]pyrene, dibenzo[a,l]pyrene, coronene and corannulene. The primary reaction is always hydrogen atom loss, with smaller species also exhibiting loss C2H2 varying extents. Combined previous work on PAH ions, trends in energies (E0) for H...

Vector modes are fully polarized of light with spatially varying polarization distributions, and they have found widespread use in numerous applications such as microscopy, metrology, optical trapping, nanophotonics, communications. The entanglement has attracted significant interest, it been shown to tremendous potential expanding existing enabling new ones. However, due the complex structure entangled vector (EVMs), a complete characterization these remains challenging time consuming....

Optical fiber links and networks are integral components within between cities' communication infrastructures. Implementing quantum cryptographic protocols on either existing or new will provide information-theoretical security to data transmissions. However, there is a need for ways increase the channel bandwidth. Using transverse spatial degree of freedom one way transmit more information tolerable error thresholds by extending common qubit high-dimensional key distribution (QKD) schemes....

Free electron beams that carry high values of orbital angular momentum (OAM) possess large magnetic moments along the propagation direction. This makes them an ideal probe for measuring electronic and properties materials, as well fundamental experiments in magnetism. However, their generation requires use complex diffractive elements, which usually take form nano-fabricated holograms. Here, we show how limitations current fabrication such holograms can be overcome by using beam lithography....

Abstract Underwater quantum communication has recently been explored using polarization and orbital angular momentum (OAM). Here, we show that spatially structured modes, e.g., a coherent superposition of beams carrying both OAM, can also be used for underwater cryptography. We use the degree freedom to investigate impact channel length on key rates applications. The proves difficult environment establishing as optical turbulence results in significant beam wandering distortions. However,...

We examine the propagation of optical beams possessing different polarization states and spatial modes through Ottawa River in Canada. A Shack-Hartmann wavefront sensor is used to record distorted beam's wavefront. The turbulence underwater channel analysed, associated Zernike coefficients are obtained real-time. Finally, we explore feasibility transmitting as well for applications quantum cryptography.

Quantum - or classically correlated light can be employed in various ways to improve resolution and measurement sensitivity. In an "interaction-free" measurement, a single photon used reveal the presence of object placed within one arm interferometer without being absorbed by it. This method has previously been applied imaging. With technique known as "ghost imaging", entangled pairs are for detecting opaque with significantly improved signal-to-noise ratio while preventing...

Nearly 30 years ago, two-photon interference was observed, marking the beginning of a new quantum era. Indeed, has no classical analogue, giving it distinct advantage for range applications. The peculiarities physics may now be used to our outperform computations, securely communicate information, simulate highly complex physical systems and increase sensitivity precise measurements. This separation from motivated physicists study two-particle both fermionic bosonic objects. So far, been...

Quantum key distribution (QKD) offers the possibility for two individuals to communicate a securely encrypted message. A common technical requirement is monitoring of signal disturbance in QKD system bound information leakage toward an unwanted eavesdropper. Recently, round-robin differential-phase-shift (RRDPS) protocol, which encodes bits high-dimensional state space, was proposed introduce upper on amount Eve's based dimensionality prepared quantum states and randomized measurement...

The dissociation of the anthracene radical cation has been studied using two different methods: imaging photoelectron photoion coincidence spectrometry (iPEPCO) and atmospheric pressure chemical ionization-collision induced mass (APCI-CID). Four reactions were investigated: (R1) C14H10(+•) → C14H9(+) + H, (R2) C14H8(+•) (R3) C12H8(+•) C2H2 (R4) C10H8(+•) C4H2. An attempt was made to assign structures each fragment ion, although there is still room for debate whether ion a...

Free electrons with a helical phase front, referred to as "twisted" electrons, possess an orbital angular momentum (OAM) and, hence, quantized magnetic dipole moment along their propagation direction. This intrinsic can be used probe material properties. Twisted thus have numerous potential applications in materials science. Measuring this quantity often relies on series of projective measurements that subsequently change the OAM carried by electrons. In Letter, we propose nondestructive way...

Liquid crystals allow for the real-time control of polarization light. We describe and provide some experimental examples types general transformations, including universal that can be accomplished with liquid in tandem fixed waveplates. Implementing these transformations an array crystals, e.g., a spatial light modulator, allows manipulation across beam's transverse plane. outline applications such generation exotic vector polarized beams, magnifier, correction aberrations fields.

Recently, a new device to measure the orbital angular momentum (OAM) electronic spectrum after elastic/inelastic scattering in transmission electron microscope has been introduced. We modified theoretical framework needed describe conventional low-loss energy loss spectroscopy (EELS) experiments microscopes (TEM) study surface plasmons metallic nanostructures, allow for an OAM post selection and devise analysis of these excitations nanostructures. found that unprecedented information on...

The characterization of quantum processes, e.g. communication channels, is an essential ingredient for establishing information systems. For key distribution protocols, the amount overall noise in channel determines rate at which secret bits are distributed between authorized partners. In particular, tomographic protocols allow full reconstruction, and thus characterization, channel. Here, we perform process tomography high-dimensional channels with dimensions ranging from 2 to 5. We can...

The polarization of a monochromatic optical beam lies in plane, and general, is described by an ellipse, known as the ellipse. ellipse tight focusing (non-paraxial) regime forms non-trivial three-dimensional topologies, such M\"obius ribbon strips, well knots. latter formed when dynamics specific states, e.g., circular are studied upon propagation. However, there alternative method to generate knots: electric field's tip can be made evolve along knot trajectory time locally. We propose...

Quantum walks present novel tools for redesigning quantum algorithms, universal computations, and simulators. Hitherto, one- two-dimensional systems (lattices) have been simulated studied with photonic systems. Here, we report the simulation of cyclic systems, such as hexagonal structures. We experimentally explore wavefunction dynamics probability distribution a particle located on six-site system, along three- four-site while under different initial conditions. Various walk employing...

Four molecules were investigated by imaging photoelectron photoion coincidence (iPEPICO) spectroscopy: 1-propynylbenzene, indene, ethynylbenzene, and benzocyclobutene. Their threshold spectrum was obtained electronic transitions assigned OVGF (outer valence Green's function) calculations. Vibrational progressions observed in the ground excited states simulated calculating Franck–Condon factors based on neutral as well cation state geometries. iPEPICO used to obtain ion dissociation data...

When an external field is applied across a liquid-crystal cell, the twist and tilt distributions cannot be calculated analytically must extracted numerically. In standard approach, Euler-Lagrange equations are derived from minimization of free energy system then solved via finite-difference methods, often implemented in commercial software. These tools iterate initial solutions that compatible with boundary conditions, providing limited to no flexibility for customization. Here, we present...

When an external field is applied across a liquid-crystal cell, the twist and tilt distributions cannot be calculated analytically must extracted numerically. In standard approach, Euler-Lagrange equations are derived from minimization of free energy system then solved via finite-difference methods, often implemented in commercial software. These tools iterate initial solutions that compatible with boundary conditions, providing limited to no flexibility for customization. Here we present...

Nematic liquid-crystal devices are a powerful tool to structure light in different degrees of freedom, both classical and quantum regimes. Most these exploit the possibility introducing position-dependent phase retardation either with homogeneous alignment optic axis—e.g., liquid-crystal-based spatial modulators—or, conversely, uniform but tunable patterned axis, e.g., q-plates. The pattern is same latter case on two layers. Here, more general considered, wherein front back layers...

Quantum communication has been successfully implemented in optical fibres and through free-space [1-3]. Fibre systems, though capable of fast key rates low quantum bit error (QBERs), are impractical communicating with destinations without an established fibre link [4]. Free-space channels can overcome such limitations reach long distances the advent satellite-to-ground links [5-8]. Shorter line-of-sight have also realized for intra-city conditions [2, 9]. However, turbulence, resulting from...

A fast and automated scheme for general polarization transformations holds great value in adaptive optics, quantum information, virtually all applications involving light-matter light-light interactions. We present an experiment that uses a liquid crystal on silicon spatial light modulator to perform field. experimentally demonstrate the point-by-point conversion of uniformly polarized fields across wavefront realize arbitrary, spatially varying states. Additionally, we field with arbitrary...