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Quantum key distribution (QKD) has emerged as a secure solution of secret key distribution utilizing the well established theories of modern physics. Since its introduction in 1984, many interesting and innovative ideas have been proposed for QKD in order to improve the security and efficiency of the scheme keeping in view of its applications and practical implementation. High error rate QKD scheme for long distance communication - the so-called KMB09 protocol - is one such scheme which was designed to achieve longer communication distance in QKD, without compromising its security, by allowing the utilisation of higher dimensional photon states which is not possible with standard BB84 scheme. However the practical implementation of KMB09 protocol has not been presented yet because of its unique design. In this paper, we propose a framework for the practical implementation of QKD system that runs KMB09 protocol in two or more dimensions of photon states. We present the KMB09 based QKD system design and its simulation for practical implementation based on the encoding of secret bits in higher order Gaussian beam spatial modes. The proposed framework is specifically evaluated in terms of efficiency or success rate with two and four dimensions of photon states. We find that the simulation results of the proposed framework are inline with the numerical and analytical results of the same QKD model presented earlier. [ABSTRACT FROM AUTHOR]

Quantum key distribution (QKD) is a proven secured way to transmit shared secret keys using quantum particles. Any adversarial attempt to intercept and eavesdrop secret key results in generating errors alerting the legitimate users. Since QKD is constrained by quantum mechanics principles, the practical transmission of the key at a greater distance is an issue. In this paper, we discover and analyze the key factors associated with transmission media, hardware components and protocol implementation of the QKD system that causes hindrance in distance range. Practical implementation of BB84 and KMB09 protocols is discussed to determine the achievable distance given current technology. We find that by using ultra low loss fiber, short-pulse laser and superconducting nanowire single photon detector the maximum achievable distance for both of the quantum protocols is 250 km. [ABSTRACT FROM AUTHOR]