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The quantum key distribution playing the role of trusted carrier to augment the symmetric key distribution and is competing with public key cryptography in case of reliability and security. It is secure against unlimited computing power. In the implementation front of quantum key distribution, there is an intersection of fields like quantum physics, optics, computer science and electronics make it more complex. In this paper, we proposed Quantum key distribution technique in which traditional cryptographic techniques are not needed for mutually authenticating the keys. We proposed the base distribution center as a third party, in which both communicating parties share their bases before communication and mutually authenticate each other by transmitting a series of bits and deduce the encryption and decryption keys.

We propose a microscopic description of the crystal symmetry deriving high-order harmonic generation selection rules by using a theory not relying on the perturbative expansion. The results give us how the contributions of different k-points forms the selection rule.

Optical angular momentum provides a useful dimension for data multiplexing and quantum entanglement. However, the demultiplexing of optical angular momentum is often performed by complex bulk optics and multiple detectors. Here we demonstrate that chiral plasmonic electrodes can be used to selectively detect optical angular momentum in a compact and integrated format. We demonstrate direct detection of photon spin and investigate methods for the detection of orbital angular momentum.

We show how the semiclassical formulas for radiation emission of Baier, Katkov and Strakhovenko for arbitrary initial and final spins of the electron and arbitrary polarization of the emitted photon can be rewritten in a form which numerically converges quickly. We directly compare the method in the case of a background plane wave with the result obtained by using the Volkov state solution of the Dirac equation, and confirm that we obtain the same result. We then investigate the interaction of a circularly polarized short laser pulse scattering with GeV electrons and see that the finite duration of the pulse leads to a lower transfer of circular polarization than that predicted by the known formulas in the monochromatic case. We also see how the transfer of circular polarization from the laser beam to the gamma ray beam is gradually deteriorated as the laser intensity increases, entering the nonlinear regime. However, this is shown to be recovered if the scattered photon beam is collimated to only allow for passage of photons emitted with angles smaller than 1/γ with respect to the initial electron direction, where γ is the approximately constant Lorentz factor of the electron. The obtained formulas also allow us to answer questions regarding radiative polarization of the emitting particles. In this respect we briefly discuss an application of the present approach to the case of a bent crystal and high-energy positrons.

Publisher's version (útgefin grein)., The transport properties of a wire-dot system coupled to a quantized single photon with linear polarization in a 3D-cavity is theoretically studied using a quantum master equation. The system is also coupled to a photon reservoir, environment. We interplay between the electron-photon coupling, gγ, and the cavity-reservoir coupling, κ, in three cases: κgγ. The current peaks due to intraband transitions between the Rabi-resonant states are formed when the electron-photon coupling is dominant, κ, This work was financially supported by the Research Fund of the University of Iceland , the Icelandic Research Fund , Grant No. 163082-051 , and the Icelandic Infrastructure Fund . The computations were performed on resources provided by the Icelandic High Performance Computing Center at the University of Iceland . NRA acknowledges support from University of Sulaimani and Komar University of Science and Technology .

The present study explored possible psychophysical interactions between focused mental intention and the electromagnetic field vector, i.e., polarization. To detect the hypothesized effect, a laser beam was passed through horizontal and vertical polarizers. Participants were asked to focus their attention on the beam between the two polarizers while holding the intention for the beam’s polarization to rotate. If the photons’ electric field vector was affected, then the illumination intensity of the beam exiting the second polarizer should increase. Two exploratory experiments both showed results contrary to the hypothesis, with illumination decreasing during periods when intention was focused toward the beam as compared to periods where attention was withdrawn. Reanalysis of data from previously published experiments, also involving mental influence of beams of light, but designed for different purposes and originally analyzed in other ways, also showed a reduction in light intensity during periods of focused attention. These studies suggest that psychophysical interactions with light appears to result in scattering or absorbing photons. Further research is warranted to confirm these results.

Trapped atomic ions are an ideal candidate for quantum network nodes, with long-lived identical qubit memories that can be locally entangled through their Coulomb interaction and remotely entangled through photonic channels. The integrity of this photonic interface is generally reliant on the purity of single photons produced by the quantum memory. Here, we demonstrate a single-photon source for quantum networking based on a trapped 138Ba+ ion with a single photon purity of g (2)(0)=(8.1±2.3)×10−5 without background subtraction. We further optimize the tradeoff between the photonic generation rate and the memory-photon entanglement fidelity for the case of polarization photonic qubits by tailoring the spatial mode of the collected light.

The Wigner representation of parametric down conversion in the Heisenberg picture is applied to the study of the Rome teleportation experiment. We investigate the physical meaning of the zeropoint inputs at the different areas of the experimental setup. In particular, we establish a quantitative relationship between the zeropoint sets of modes that are needed for the preparation of the quantum state to be teleported, the idle channels inside the one-photon polarization-momentum Bell-state analyser, and the possibility of performing teleportation of a polarization state whith certainty., 32 pages, 1 Figure

In the air-water quantum key distribution (QKD), the irregular sea surface has some influence on the photon polarization state. The wind is considered as the main factor causing the irregularity, so the model of irregular sea surface based on the wind speed is adopted. The relationships of the quantum bit error rate with the wind speed and the initial incident angle are simulated. Therefore, the maximum secure transmission depth of QKD is confirmed, and the limitation of the wind speed and the initial incident angle is determined. The simulation results show that when the wind speed and the initial incident angle increase, the performance of QKD will fall down. Under the intercept-resend attack condition, the maximum safe transmission depth of QKD is up to 105 m. To realize safe communications in the safe diving depth of submarines (100 m), the initial incident angle is requested to be not exceeding 26°, and with the initial incident angle increased, the limitation of wind speed is decreased.

In this paper, we propose a method to construct geometric-phase-based spin Hall metalens, which consists of identical metal nanoholes with spatially variant orientations. It is demonstrated that the metalens can realize simultaneous focusing for different spin states in the broad spectral range of 550–900 nm due to the extremely similar hyperbolic phase profiles at different optimized values of wavelength and focal length. The transverse and longitudinal positions of spin-dependent focal spots can be arbitrarily manipulated by adjusting the orientation angles of metal nanoholes. The intensities of the spin-dependent focal spots can be effectively controlled by the proportion of the phase profile associated with right- or left-hand circularly polarized component. In addition, our designed metalens enables the focusing beyond the optical diffraction limit across the above wavelength coverage as the phase profile only contains right or left-hand circularly polarized component. It is expected that our simple and novel metalens would be applied in polarimetric imaging, optical sensing, and photon spin splitting.

We present an experimental investigation of two-photon interference using a continuous-wave laser. We demonstrate the violation of the CHSH inequality using the phase randomized weak coherent states from a continuous wave laser. Our implementation serves as an approach to reveal the quantum nature of a source that is considered to be a classical source., 6 pages, 2 figures

We present a simplified web-based application for simulating x-ray and photoelectron spectra of transition metals, built around the notion that web-based applications lower the bar for novice users. The application provides a simple interface to simulate x-ray absorption spectroscopy, resonant inelastic x-ray scattering, and angle-resolved photoemission spectroscopy, incorporating the effects of local electronic interactions, which give rise to multiplets, spin-orbit coupling, crystal field effects, and ligand hybridization/charge transfer. Results can be obtained that highlight the key role of photon polarization., Comment: 6 pages, 10 figures. Software can be accessed at https://www-times.stanford.edu/index and https://times-webxrs.stanford.edu

On-chip controlling of photon spin is essential in developing future integrated nanophotonics with complex functionalities. Here we propose and demonstrate a robust spin-sorting nanocircuit, which consists of a spin-orbit coupler (i.e., combined nanoring and nanodisk) and an L-shaped dielectric-loaded surface plasmon (DLSPs) waveguide. The nanocircuit with optimized geometric parameters is shown to be capable of unidirectionally exciting and routing a DLSP mode along an independent waveguide. We found experimentally that the proposed device possesses an average insertion loss (extinction ratio) of 0.13 dB (14.8 dB) under complete circularly polarized incidence with opposite spin, which is in good agreement with theoretical calculations. The proposed spin-selective scheme may pave the way for applications in the manipulation of chirality with a flexible degree of freedom.

A fundamental feature of micro objects is the wave-particle duality which is addressed by Bohr’s complementarity principle. To observe the wave and particle behaviours, quantum delayed-choice experiments based on linear optics have been realized at the single-photon level. Since they were performed by using a single photon as the input, repeating measurements were required in order to obtain different experimental data and adjusting experimental parameters was necessary prior to each of measurements. Different from the previous works, we here realize a simulation of quantum delayed-choice experiment through a single shot, which employs a classical intense light beam as the input instead of a single photon. Experimentally, we demonstrate the trade-off between distinguishability and visibility of photons in a two-arm interferometer in an intuitive way by utilizing the finite beam profile of the light. We observe the morphing between wave and particle natures of photons via a single shot of a charged-coupled-device camera. Since the image is captured within the exposure time which is several milliseconds, the phase fluctuation is negligible, and therefore our experimental setup is robust against the noise. This work provides a simple and new route to inspect quantum duality, which does not require adjusting experimental parameters frequently and only needs performing measurement once.

Wavelength is an essential factor affecting polarization propagation. We investigate the polarization persistence of linearly polarized light from ultraviolet to near-IR in foggy environments. Certain spectral bands, from ultraviolet to IR wavelengths that exhibit lower path loss, were initially selected. Using polarization-tracking Monte Carlo simulations for varying particle size, wavelength, refractive index and detection range, it is shown that linear polarization exhibits different persistence performance at different wavelengths in various foggy environments. For wet haze of 0.6 µm or 1 µm droplets, parallel polarization increases persistently as the wavelength increases, and has superior persistence in the near-IR region. For radiation fog of 5 µm or 7.5 µm droplets, parallel polarization shows superior persistence in the ultraviolet region. For advection fog of 15 µm or 45 µm droplets, parallel polarization shows a superior persistence in the ultraviolet region. It is therefore shown that changing the wavelength can improve linear polarization persistence in foggy environments.

This research is a study of the photon radiation from the bilayer graphene perturbed by the electromagnetic field. Theoretically, our simulation shows vividly the asymmetry property of such bilayer graphene resulting in the outstanding attribute of the photon emission profiles. The methods employed in our work are a tight-binding model in the many-body system and Fermi’s golden rule. In this work, we show the emission profiles in various kinds such as the single-photon emission (both in linear polarization and circular polarization) and the double photon emission. Additionally, in the case of double photon emission, we illustrate the degree of entanglement between photon pairs by analyzing the certain coincident rate involved indirectly in the emission profiles. The results demonstrate that the degree of entanglement is maximum when the photon pair’s direction is perpendicular to each other (especially, in the case that one of the photons emits in the direction being perpendicular to the bilayer graphene plane). We also discover that the direction of the maximum entangled photons depends on the polarization between the photon’s pairs.

Polarization imaging can quantitatively probe the characteristic microstructural features of biological tissues non-invasively. In biomedical tissues, layered structures are common. Superposition of two simple layers can result in a complex Mueller matrix, and multi-color backscattering polarimetry can help to probe layered structures. In this work, multi-color backscattering Mueller matrix images are measured for living nude mice skins. Preliminary analysis of anisotropy parameter A and linear polarizance parameter b show signs of a layered structure in the skin. For more detailed examinations on polarization features of layered samples, we generate Mueller matrices by experimenting with two-layered thick tissues and concentrically aligned silk submerged in milk. Then we use supervised machine learning to identify polarization parameters that are sensitive to layered structure and guide the synthesis of more parameters. Monte Carlo simulation is also adopted to explore the relationship between parameters and microstructures of media. We conclude that multi-color backscattering polarimetry combined with supervised machine learning can be applied to probe the characteristic microstructure in layered living tissue samples.

In this work, we develop a design methodology to generate spectrally pure photon pairs in asymmetric heterogeneously coupled waveguides by spontaneous parametric down-conversion. Mode coupling in a system of waveguides is used to directly tailor the group velocity of a supermode to achieve group velocity matching (GVM) that is otherwise not allowed by material dispersion. Design examples based on thin film lithium niobate waveguides are provided, demonstrating high spectral purity and temperature tunability. This approach is a versatile strategy applicable to waveguides of different materials and structures, allowing more versatility in single-photon source designs., Comment: 4 pages, 5 figures

In order to obtain stable spectral data of copper plasma, a detection platform of polarization-resolved laser-induced breakdown spectroscopy (PRLIBS) was built. The PRLIBS characteristic function of copper was constructed by combining the spectral path of plasma discrete spectrum and contact spectrum. The system can not only measure the original data, but also obtain the polarization information in the spectral data. By analyzing the extraction method of spatial polarized light information, the characteristic model of S-wave intensity information in PRLIBS was derived. The results show that in the decay process of plasma energy, the anisotropy of plasma recombination under local thermal equilibrium makes the number of deflected particles of atoms and electrons different in unit time, which leads to the polarization of radiation. The polarization characteristics of the plasma spectrum decreased with the increase of laser energy density. The S-wave was very active, and the polarization of continuous media was much stronger than that of discrete line emission. The advantages were helpful to obtain more stable characteristic peak signals. As a plasma element identification method, PRLIBS makes up for the deficiency of plasma detection technology, and can provide a scientific basis for the safety and non-destructive detection of heavy metals.

Polarization sensitive quantum optical coherence tomography (PS-QOCT) is used to characterize birefringence, scattering/absorption and path length differences in a flat transparent plastic sample. In this Letter, we present the first, to the best of our knowledge, experimental technique of PS-QOCT imaging and characterization of a birefringent material. Polarization sensitive coincidence rate of the entangled photons measured for each pixel and the 2D cross-sectional images are reconstructed. The technique described in this work has many potential applications in the characterization of micro and nano structures, including biological samples.

The process of two-photon emission (Ze)* → (Ze) + 2γ of a hydrogenlike atom is considered with spin states of the electron and polarization of the photons taken into account, which had not been done before. A general expression for the probability of the process per unit time has been obtained for different polarization states of the photons with a formulation of hard and soft selection rules for the quantum numbers m and l. It is shown that by virtue of the established specifics of the properties of the two-photon emission process (absence of a Zeeman effect and dependence of the probability on the polarization states of the photons), it can in principle be identified against the background of single-photon emission (Ze)* → (Ze) + γ, despite the presence of additional small factors: 1) α = e 2/ћc ≈ 1/137 of the perturbation theory in e, and 2) the square of the atomic expansion parameter (Zα)2 in the expression for the probability.

We investigate photoproduction of charged ρ off the nucleon using ρ ( 770 ) + π ( 140 ) Regge pole exchanges by considering the ρ -meson electromagnetic multipole moments. The significance of the Ward identity at the γρρ vertex is emphasized for current conservation in the process. Given π exchange with the well-known coupling constants for γπρ and πNN , we analyze the role of the ρ exchange in the γ p → ρ + n and γ n → ρ − p processes without model-dependences except for the magnetic moment μ ρ ± = ± 2.01 and electric quadrupole moment Q ρ ± = ± 0.027 fm 2 taken from theoretical estimates. The nondiffractive feature of both cross sections is reproduced with a rapid decrease beyond the resonance region by the dominance of π exchange over the ρ . Cross sections for differential and density matrix elements are presented to compare with existing data. The parity and photon polarization asymmetries are predicted to demonstrate the apparent roles of the ρ -meson electromagnetic multipole moments.

At present, the research of single-photon is a hot topic, it has been widely applied in quantum measurement, quantum entanglement and quantum information. In this paper, we have proposed a new single photon theory, which is the vector potential A rotation at the vertical motion direction of photon, it can produce the microscopic electric field and magnetic field, and they satisfy the Maxwell equations. We have calculated photon spin, momentum, energy, and found there are left-handed and right-handed photon. In addition, we study the multi-photon theory and the dynamics theory between photons interaction. On this basis, we have further given the compound structures of electron, proton, neutron, neutrino, π meson, dark matter with the photon structural theory, and calculated their mass, charge and spin.

Precise measurements on rare radiative B decays are performed with the LHCb experiment at LHC. The LHCb results regarding the ratio of branching fractions for two radiative decays, B0 → K*0γ and Bs → ϕγ, the direct CP asymmetry in B0 → K*0γ decay channel and the observation of the photon polarization in the B± → K±π∓π±γ decay, are included. The first two measurements were performed in 1 fb–1 of pp collisions data and the third one in 3 fb–1 of data, respectively.

Double-band circular polarization conversion based on novel e -shape resonators is proposed and studied both numerically and experimentally. Both the simulated results and experimental results are in good agreement. At two resonant frequencies, i.e., 11.65 GHz and 13.02 GHz, the incident y-direction linearly polarized wave can be transformed into right- and left-handed circularly polarized waves, respectively. The proposed structure can transmit a nearly pure circularly polarized wave, with a polarization extinction ratio of greater than 30 dB. Moreover, the metasurface is compact with simple geometry, which is not only extremely thin in the propagating direction but also very small in the transverse direction. The retrieval results reveal that the effective refractive index of the e -shape structure is nearly negative in the vicinity of resonant frequencies. The surface current distributions are investigated to illustrate the polarization transformation mechanism. We also analyze the influence of several main geometric parameters for regulating the polarization properties. The proposed e -shape structure is promising for use in the design of polarization control devices.

A sizable right-handed photon polarization in b→sγ is a clear signal for new physics. In this Letter, we point out that the photon helicity in b→sγ can be unambiguously extracted by combining the measurements in B→K1γ and the Cabibbo-favored D→K1e+ν decay. We propose a ratio of up-down asymmetries in D→K1e+ν to quantify the hadronic effects. A method for measuring, in experiment, the involved partial decay widths in the ratio is discussed, and experimental facilities like BESIII, Belle-II and LHCb are likely to measure this ratio. We also give the angular distribution that is useful for extracting the photon polarization in the presence of different kaon resonances.

Publisher's version (útgefin grein)., Transport properties of a quantum dot coupled to a photon cavity are investigated using a quantum master equation in the steady-state regime. In the off-resonance regime, when the photon energy is smaller than the energy spacing between the lowest electron states of the quantum dot, we calculate the current that is generated by photon replica states as the electronic system is pumped with photons. Tuning the electron-photon coupling strength, the photocurrent can be enhanced by the influences of the photon polarization, and the cavity-photon coupling strength of the environment. We show that the current generated through the photon replicas is very sensitive to the photon polarization, but it is not strongly dependent on the average number of photons in the environment., This work was financially supported by the Research Fund of the University of Iceland, the Icelandic Research Fund, grant no. 163082-051, and the Icelandic Infrastructure Fund. The computations were performed on resources provided by the Icelandic High Performance Computing Center at the University of Iceland. NRA acknowledges support from University of Sulaimani and Komar University of Science and Technology. CST acknowledges support from Ministry of Science and Technology of Taiwan under grant No. 106-2112-M-239-001-MY3.

The interplay of photon spin and orbital angular momentum (OAM) in the optical fiber (one-dimensional waveguide) has recently risen to the forefront of quantum nanophotonics. Here, we introduce the fermionic dual of the optical fiber, the Dirac wire, which exhibits unique electronic spin and OAM properties arising from confined solutions of the Dirac equation. The Dirac wires analyzed here represent cylindrical generalizations of the Jackiw-Rebbi domain wall and the minimal topological insulator, which are of significant interest in spintronics. We show the unique longitudinal spin arising from electrons confined to propagation in a wire, an effect which is fundamentally prohibited in planar geometries. Our work sheds light on the universal spatial dynamics of electron spin in confined geometries and the duality between electronic and photonic spin.

Quantum key distribution (QKD) can generate secure key bits between remote users employing the features of quantum physics. However, a shared reference frame is necessary for QKD systems in most scenarios. A reference-frame-independent (RFI) scheme can tolerate the reference frame drifting between legitimate remote users, which is significant in the operation of relative moving terminals such as satellites and aircraft. We design and experimentally demonstrate an RFI-BB84-QKD system by joint encoding with the polarization and orbital angular momentum states of the photons. We use self-compensating fiber Sagnac interferometers to perform high-speed polarization modulation, and q-plates to passively manipulate the rotation-invariant photon states, which makes the system feasible for high-speed operation using off-the-shelf components.

The time-dependent CP asymmetry in B 0 → K resγ → π+π− K Sγ is sensitive to the photon polarisation in the quark level process b → sγ. While this polarisation is predominantly left-handed in the standard model, it could be modified by the existence of new physics contributions that may possess different CP properties. In this paper, we derive the CP violation formulae for B 0 → K resγ → π+π− K Sγ including the most dominant intermediate states. We propose a new observable that could be measured in a time-dependent amplitude analysis of B 0 → π+π− K Sγ decays, providing a stringent contraint on the photon polarisation. We discuss the future prospects for obtaining such constraints from measurements at Belle II and LHCb.

Nonlocal measurement, or instantaneous measurement of nonlocal observables, is a considerably difficult task even for a simple form of product observable since relativistic causality prohibits interaction between spacelike separate subsystems. Following a recent proposal for effectively creating the von Neumann measurement Hamiltonian of nonlocal observables [Brodutch and Cohen, Phys. Rev. Lett. 116, 070404 (2016)], here we report a proof-of-principle demonstration of nonlocally measuring a product observable using linear optics without the violation of relativistic causality. Our scheme provides a feasible approach to perform nonlocal measurements via quantum erasure with linear optics., 4 pages, 3 figures, accepted for publication in Optica

We present an efficient and robust source of photons at the $^{87}$Rb D1-line (795 nm) with a narrow bandwidth of $\delta=226(1)$ MHz. The source is based on non-degenerate, cavity-enhanced spontaneous parametric down-conversion in a monolithic optical parametric oscillator far below threshold. The setup allows for efficient coupling to single mode fibers. A heralding efficiency of $\eta_{\mathrm{heralded}}=45(5)$ % is achieved, and the uncorrected number of detected photon pairs is $3.8 \times 10^{3}/(\textrm{s mW})$. For pair generation rates up to $5\times 10^{5}/$s, the source emits heralded single photons with a normalized, heralded, second-order correlation function $g^{(2)}_{c} 2$ GHz by applying mechanical strain., Comment: 6 pages, 4 figures

We propose to measure the linear polarization of the external electromagnetic fields of a relativistic heavy ion through azimuthal asymmetries in dilepton production in ultraperipheral collisions. The asymmetries estimated with the equivalent photon approximation are shown to be sizable., The version accepted by the journal, 7 pages, 4 figures

Time reversal symmetry stands as a fundamental restriction on the vast majority of optical systems and devices. The reciprocal nature of Maxwell’s equations in linear, time-invariant media adds complexity and scale to photonic diodes, isolators, circulators and also sets fundamental efficiency limits on optical energy conversion. Though many theoretical proposals and low frequency demonstrations of nonreciprocity exist, Faraday rotation remains the only known nonreciprocal mechanism that persists down to the atomic scale. Here, we present photon-spin-polarized stimulated Raman scattering as a new nonreciprocal optical phenomenon which has, in principle, no lower size limit. Exploiting this process, we numerically demonstrate nanoscale nonreciprocal transmission of free-space beams at near-infrared frequencies with a 250 nm thick silicon metasurface as well as a fully-subwavelength plasmonic gap nanoantenna. In revealing all-optical spin-splitting, our results provide a foundation for compact nonreciprocal communication and computing technologies, from nanoscale optical isolators and full-duplex nanoantennas to topologically-protected networks., Here, the authors introduce and study theoretically and numerically a scheme for breaking time-reversal symmetry and achieving nonreciprocity on the nanoscale, using spin-selective stimulated Raman scattering. These results could pave the way for compact nonreciprocal communication and computing technologies.

Upon polarimetry the polarization state of light can be obtained for different depolarizing or non-depolarizing medias such as biological specimens. Tissue polarimetry can facilitate a differentiation between healthy and (pre)cancerous tissues, without using any contrast agents and ionizing radiation. Early cancer detection is vital to increase the life expectancy of patients. Turbid medias like biological tissues can change the state and/or decrease the initial polarization of light. Circularly polarized light is preferred as found to possess better ability to detect abnormal changes in tissues, compared to linearly polarized light. In this paper we analyse polarimetric parameters, measured with Thorlabs Stokes meter included in tissue polarimetric experimental set- up in reflection geometry and multiple ex vivo colon samples. The polarimetric device operates in the spectral range between 400 nm and 700 nm, where all experiments had been conducted with wavelength of 635 nm. By reaching reference values for the polarimetric parameters we can propose a theoretical Mueller matrix, that can be used to describe the depolarization properties of the colon samples used in the experiments. The proposed Mueller matrix is to be modelled and experimentally validated to find out if it matches the theory and can be further decomposed to three matrices of depolarization, diattenuation and retardance. All of the aforementioned experimental approaches are a step closer to a pre-clinical trial, which is a bridge to the final and the most challenging goal - tissue polarimetric set-up for in vivo diagnostics.

We discuss a class of interactions between self-confined optical beams breaking the action-reaction principle. The effective force intertwining the beams does not satisfy momentum conservation, paving the way to the potential existence of situations where both beams are pushed in the same direction, in turn leading to the so-called diametric drive. In our theoretical proposal the interaction between the two light beams is enabled by optical nonlinearity. The nonlinearity is assumed to change sign with the light polarization, in turn allowing the two light beams to be attracted or repelled by an inhomogeneous region according to the photon polarization. We demonstrate that this exotic type of nonlinear spin-orbit-like interaction can be achieved in nematic liquid crystals (NLCs). In fact, depending on the input polarization, in NLCs a change in temperature corresponds to a focusing or defocusing index change. For the polarization seeing a thermal defocusing response (corresponding to the extraordinary component), the self-confinement is ensured by the simultaneous action of reorientational nonlinearity.

Properties and applications of a plasmonic cross-shaped nano-antenna is presented and compared to those of array of holes. A simple analytical model based on the superposition of waves are proposed and compared to the numerical results. A direct consequence of unequal path for two orthogonal surface waves leads to a coherent quantum interferometer with interesting properties. Mechanism behind the rotating surface charge densities and consequently, the formation of rotating resultant dipole moments is identified and the concept of Dipole-SPP-LSP-Stokes coupling is introduced. All of which leads to the most significant findings (a) foundation of a three-level quantum system for entangled photons, based on the polarization states of the transmitted light and (b) further encapsulation of the three-level quantum system into a continuous orthonormal set of pure quantum states (c) an inference on the nonexistence of spin in a single photon, hence the requirement of two photons to create such spin states., Comment: Removed unnecessary notions/acknowledgement. Reference to the version of my thesis uploaded to arXiv (arXiv:1912.10888) was added

Gate-defined quantum dots (QDs) are such a highly-tunable quantum system in which single spins can be electrically coupled, manipulated, and measured. However, the spins in gate-defined QDs are lacking its interface to free-space photons. Here, we verify that a circularly-polarized single photon can excite a single electron spin via the transfer of angular momentum, measured using Pauli spin blockade (PSB) in a double QD. We monitor the inter-dot charge tunneling which only occur when the photo-electron spin in one QD is anti-parallel to the electron spin in the other. This allows us to detect single photo-electrons in the spin-up/down basis using PSB. The photon polarization dependence of the excited spin state was finally confirmed for the heavy-hole exciton excitation. The angular momentum transfer observed here is a fundamental step providing a route to instant injection of spins, distributing single spin information, and possibly towards extending quantum communication., Gate-defined quantum dots offer a way to engineer electrically controllable quantum systems with potential for information processing. Here, the authors transfer angular momentum from the polarization of a single photon to the spin of a single electron in a gate-defined double quantum dot.

We study the transport properties of a wire-dot system coupled to a cavity and a photon reservoir. The system is considered to be microstructured from a two-dimensional electron gas in a GaAs heterostructure. The 3D photon cavity is active in the far-infrared or the terahertz regime. Tuning the photon energy, Rabi-resonant states emerge and in turn resonant current peaks are observed. We demonstrate the effects of the cavity&ndash, photon reservoir coupling, the mean photon number in the reservoir, the electron&ndash, photon coupling and the photon polarization on the intraband transitions occurring between the Rabi-resonant states, and on the corresponding resonant current peaks. The Rabi-splitting can be controlled by the photon polarization and the electron&ndash, photon coupling strength. In the selected range of the parameters, the electron&ndash, photon coupling and the cavity-environment coupling strengths, we observe the results of the Purcell effect enhancing the current peaks through the cavity by increasing the cavity&ndash, reservoir coupling, while they decrease with increasing electron&ndash, photon coupling. In addition, the resonant current peaks are also sensitive to the mean number of photons in the reservoir.