Proof-of-Concept of Real-World Quantum Key Distribution with Quantum Frames

We propose and experimentally investigate a fibre-based quantum key distribution system, which employs polarization qubits encoded into faint laser pulses. As a novel feature, it allows sending of classical framing information via sequences of strong laser pulses that precede the quantum data. This allows synchronization, sender and receiver identification, and compensation of time-varying birefringence in the communication channel. In addition, this method also provides a platform to communicate implementation specific information such as encoding and protocol in view of future optical quantum networks. Furthermore, we report on our current effort to develop high-rate error correction.Comment: 25 pages, 14 figures, 4 table

Non-linear signal processing using index calculus DBNS arithmetic

This paper discusses the use of a recently introduced index calculus Double-Base Number System (IDBNS) for representing and processing numbers for non-linear digital signal processing; the target application is a digital hearing aid processor. The IDBNS representation uses 2 orthogonal bases (2 and 3) to represent real numbers with arbitrary precision. By restricting the number of digits to one or two, it is possible to efficiently represent the real number using the indices of the bases rather than the distribution of the digits. In this paper we discuss the use of the two-digit form of this representation (2-IDBNS) to efficiently perform arithmetic associated with the non-linear processing required to correct the usual forms of hearing loss in a digital hearing aid. The non-linear processing takes the form of dynamic range compression as a function of frequency band. Currently developed digital hearing instrument processors require large dynamic range representations (20-24 bits) in order to accurately generate the dynamic range compression associated with typical hearing loss. We show that the natural non-linear representation afforded by the IDBNS provides both a more efficient signal representation and a more efficient technique for processing the dynamic range compression. We pay particular attention to a novel technique of converting from a linear binary input directly to the 2-IDBNS representation using an observation of partial cyclic repetition in the indices along with near unity approximants. Keywords: Computer arithmetic; Non-linear number representation; double-base number system; Hearing loss digital processing. 1

On Efficient Techniques for Difficult Operations in One and Two-digit

The Double Base Number System (DBNS), using orthogonal bases of 2 and 3, has similar properties to the logarithmic number system (LNS) if an index calculus is used. The DBNS provides more degrees of freedom than the LNS by virtue of both the orthogonal bases and the ability to use multiple digits. As with the LNS, multiplication and division are easy but addition and subtraction are difficult. This paper introduces a technique that uses a map to a DBNS "index sequence domain", removing the need for the relatively large look-up table solution of the LNS