2012/09/13 by Manoj K. Mishra, Mishra, Manoj K, Hari Prakash +3
Computer Science · Physics and Astronomy · #FOS: Physical sciences #Optics (physics.optics) #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum Physics (quant-ph) #Quantum optics and atomic interactions
paper · pdf · doi:10.48550/arxiv.1209.2958
openalex publication_date 2012/09/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Superposition of optical coherent states |±α⟩, possessing opposite phases, play an important role as qubits in quantum information processing (QIP) tasks and are of fundamental importance in testing quantum mechanics. Passage of such superposition of coherent states (SCS) from a 50:50 beam splitter lead to generation of entangled coherent states. Recently, ququats and qutrits defined in four and three dimensional Hilbert space respectively, have attracted much attention as they offer advantage in secure quantum communication. However, practical utilization of these advantages essentially require physical realization of quantum optical ququats and qutrits. Here, we define four new multi-photonic states (MPS) with 4n +j (here, j =0, 1, 2 or 3, and n = 0, 1, ..., ∞) numbers of photon and show how the SCS can be used to encode ququat using these MPS as basis vectors of a four dimensional Hilbert space. When these MPS fall upon a 50:50 beam splitter, the resulting states are bipartite four-component entangled coherent states (BFECS) equivalently representing the entangled ququats. We briefly discuss the photon statistical properties of such MPS and BFECS. We show that these MPS and BFECS can be synthesized using even coherent states as input to an interferometer. We give a simple linear optical protocol for almost perfect teleportation of a ququat encoded in SCS with the aid of BFECS as quantum channel. We also describe how these ququats can be used for realization of higher dimensional BB84 protocol in order to increase the security of quantum key distribution. Finally, we discuss the possible advantages of using SCS as ququats and BFECS as quantum channel in different QIP tasks.