Narrow Results

On the basis of the Rytov approximation, we investigate the effects of non-Kolmogorov turbulence on the spread of the spiral spectrum and the received power of multi-modified Bessel–Gaussian Schell (MMBGS) beams carrying orbital angular momentum. Numerical results show that the spread of the spiral spectrum increases as the azimuthal index of the source increases and that an optimal value of the beam waist is obtained. We find that the spread of partially coherent MMBGS beams with short wavelength is more robust than that of beams with long wavelength. The complete reverse is true for fully coherent MMBGS beams.

Secure exchange of cryptographic keys is extremely important for any communication system where security and privacy of data is desirable. Although classical cryptographic algorithms provide computationally secure methods for secret key exchange, quantum key distribution (QKD) provides an extraordinary means to this end by guaranteeing unconditional security. Any malicious interception of communication by a man-in-the-middle on a QKD link immediately alerts sender and receiver by introducing an unavoidable error-rate. Higher-dimensional QKD protocols such as KMB09 exhibit higher eavesdropping error-rates with improved intrusion detection but their practical implementation is still awaited. In this paper, we present the design and implementation of KMB09 protocol using Laguerre–Gaussian orbital angular momentum to demonstrate and highlight the advantages of using dynamic spatial modes in QKD system. A complete error-rate analysis of KMB09 protocol implementation is presented with two different types of eavesdropping error-rates. Furthermore, we also demonstrate the decoy state method to show the robustness of the protocol against photon-number-splitting attack.

The difference between the quark orbital angular momentum (OAM) defined in light-cone gauge (Jaffe-Manohar) compared to defined using a local manifestly gauge invariant operator (Ji) is interpreted in terms of the change in quark OAM as the quark leaves the target in a DIS experiment. We also discuss the possibility to measure quark OAM directly using twist 3 GPDs, and to calculate quark OAM in lattice QCD.

‘Ethernet over WDM’ is very promising as a next-generation network technology. After some prospective Ethernet-based services are introduced, a novel WDM-based wide-area access network, combined with a regional transport network, is introduced. This network enables the efficient deployment of such services. We show a detailed system configuration of the network and OAM information channels that are effective for it. We then present its management information model in reference to the architectural transport model. This model will be useful in building network management systems.

The widespread use of DWDM technology has presented service providers with a new challenge: how to manage increasing optical channels (OChs) to provide fast, reliable services to their end customers cost effectively. OCh-level operation, administration and maintenance (OAM) function in optical are important to effective management, and digital wrapper can provide these functions.

In this paper, we propose an ITU-T Rec. Draft G.709 and G.798 based overhead processing model for OCh-level OAM.