We report on an experimental demonstration of light transfer in an engineered triple-well optical waveguide structure which provides a classic analog of coherent tunneling by adiabatic passage (CTAP) recently proposed for coherent transport in space of neutral atoms or electrons among tunneling-coupled optical traps or quantum wells [A. D. Greentree et al., Phys. Rev. B 70, 235317 (2004); K. Eckert et al., Phys. Rev. A 70, 023606 (2004)]. The direct visualization of CTAP wave-packet dynamics enabled by our simple optical system clearly shows that in the counterintuitive passage scheme light waves tunnel between the two outer wells without appreciable excitation of the middle well

Parity-Time (PT) symmetric quantum mechanics is a complex extension of conventionalHermitian quantum mechanics in which physical observables possess a real eigenvalue spectrum. However, an experimental demonstration of the true quantum nature of PT symmetry has been elusive thus far, as only single-particle physics has been exploited to date. In our work, we demonstrate two-particle quantum interference in a PT-symmetric system. We employ integrated photonic waveguides to reveal that PT-symmetric bunching of indistinguishable photons shows strongly counterintuitive features. We substantiate our experimental results by modelling the system by a quantum master equation, which we analytically solve using Lie algebra methods. Our work paves the way for nonlocal PT-symmetric quantum mechanics as a novel building block for future quantum devices.One Sentence Summary: Counterintuitive photon bunching characteristics in PT-symmetric quantum mechanics.

We study the classical optics effects known as Goos-Hänchen and Imbert-Fedorov shifts, occurring when reflecting a bounded light beam from a planar surface, by using a quantum-mechanical formalism. This new approach allows us to naturally separate the spatial shift into two parts, one independent on orbital angular momentum (OAM) and the other one showing OAM-induced spatial-versus-angular shift mixing. In addition, within this quantum-mechanical-like formalism, it becomes apparent that the angular shift is proportional to the beams angular spread, namely to the variance of the transverse components of the wave vector. Moreover, we extend our treatment to the enhancement of beam shifts via weak measurements and relate our results to the recent experiments.

Tracking the kinematics of fast-moving objects is an important diagnostic tool for science and engineering. Existing optical methods include high-speed CCD/CMOS imaging [1], streak cameras [2], lidar [3], serial time-encoded imaging [4] and sequentially timed all-optical mapping [5]. Here, we demonstrate an entirely new approach to positional and directional sensing based on the concept of classical entanglement [6][7][8] in vector beams of light. The measurement principle relies on the intrinsic correlations existing in such beams between transverse spatial modes and polarization. The latter can be determined from intensity measurements with only a few fast photodiodes, greatly outperforming the bandwidth of current CCD/CMOS devices. In this way, our setup enables two-dimensional real-time sensing with temporal resolution in the GHz range. We expect the concept to open up new directions in metrology and sensing.Vector beams of light with cylindrical, non-uniform polarization patterns [9] have found application in diverse areas of optics such as improved focusing [10], laser machining [11], plasmon excitation [12], metrology [13], optical trapping [14] and nano-optics [15][16][17]. Recently, vector beams have attracted attention [18][19][20][21][22] due to a simple but striking property: when viewed as a superposition of transverse electromagnetic modes with orthogonal linear polarizations, the nonseparable mode function of a radially polarized vector beam is mathematically equivalent to a maximally entangled Bell state of two qubits known from quantum mechanics. In contrast with the canonical Bell states in quantum optics, where two photons are entangled in polarization and exhibit non-local correlations when spatially separated, this "classical entanglement" in vector beams is necessarily local as it exists only between different degrees of freedom of one and the same physical system [23].However, these correlations have recently been shown to represent a valuable resource. Vector beams have been used to violate an analogue of Bell's inequality for spin-orbit modes [19,20] and have led to continuousvariable entanglement between different degrees of freedom [24]. In addition, vector beams have been used to implement classical counterparts of quantum protocols [25,26]. Promising proposals include an application to the study of quantum random walks [27] and realtime single-shot Mueller matrix measurements [28], and a scheme for measuring the depolarization strength of a material has been implemented [29]. In the present work, we demonstrate for the first time a fully operational application of classical entanglement to high-speed kinematic sensing. Several techniques are nowadays available for sensing the kinematics of fast-moving objects [1][2][3][4][5]. Each arXiv:1504.00697v2 [quant-ph]

We introduce a new class of nondiffracting optical pulses possessing orbital angular momentum. By generalizing the X-wave solution of the Maxwell equation, we discover the coupling between angular momentum and the temporal degrees of freedom of ultrashort pulses. The spatial twist of propagation invariant light pulse turns out to be directly related to the number of optical cycles. Our results may trigger the development of novel multilevel classical and quantum transmission channels free of dispersion and diffraction. They may also find application in the manipulation of nanostructured objects by ultrashort pulses and for novel approaches to the spatiotemporal measurements in ultrafast photonics.

The concept of quasi- symmetry in an optical wave-guiding system is elaborated by comparing the evolution dynamics of a -symmetric directional coupler and a passive directional coupler. In particular, we show that in the low-loss regime, apart from an overall exponentially damping factor that can be compensated via a dynamical renormalization of the power flow in the system along the propagation direction, the dynamics of the passive coupler fully reproduce the one in the -symmetric system.

An experimental demonstration of a classical analogue of the quantum Zeno effect for light waves propagating in engineered arrays of tunneling-coupled optical waveguides is reported. Quantitative mapping of the flow of light, based on scanning tunneling optical microscopy, clearly demonstrates that the escape dynamics of light in an optical waveguide side-coupled to a tight-binding continuum is slowed down when projective measurements, mimicked by sequential interruptions of the decay, are performed on the system.

We propose and demonstrate a femtosecond laser inscribed micro-optical device for broadband beam splitting based on the interruption of the stimulated Raman adiabatic passage. For the spectral characterization waveguide fluorescence microscopy is applied by exciting nonbridging oxygen holes and exciton defects at several wavelengths. Additionally, spectrally resolved nearfield imaging shows octave spanning 50:50 beam splitting