Simple and secure quantum key distribution with biphotons

Abstract

The best qubit one-way quantum key distribution (QKD) protocol can tolerate up to 14.1% in the error rate. It has been shown how this rate can be increased by using larger quantum systems. The polarization state of a biphoton can encode a three level quantum system - a qutrit. The realization of a QKD system with biphotons encounters several problems in generating, manipulating and detecting such photon states. We define those limitations and find within them a few protocols that perform almost as well as the ideal qutrit protocol. One advantage is that these protocols can be implemented with minor modifications into existing single photon systems. The security of one protocol is proved for the most general coherent attacks and the largest acceptable error rate for this protocol is found to be around 17.7%. This is the first time, to the best of our knowledge, that the security of qutrit QKD protocols is rigorously analyzed against general attacks.

4 pages, 4 figures, calculation error corrected, new Fig. 4, 2 new Refs. and 2 omitted

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Cited by in corpus (10)

• Coherence and Decay of Higher Energy Levels of a Superconducting Transmon Qubit
• Photon spin-to-orbital angular momentum conversion via an electrically tunable $q$-plate
• Polarization-controlled evolution of light transverse modes and associated Pancharatnam geometric phase in orbital angular momentum
• Phase-space interference of states optically truncated by quantum scissors: Generation of distinct superpositions of qudit coherent states by displacement of vacuum
• Projection of two biphoton qutrits onto a maximally entangled state
• A heralded two-qutrit entangled state
• Efficient and flexible generation of entangled qudits with cross phase modulation
• Mutually Unbiased Bases and Complementary Spin 1 Observables
• Three dimensional quantum key distribution in the presence of several eavesdroppers
• The relation between nonlocality and contextuality for a biphoton