Effect of decoherence on fidelity in teleportation using entangled coherent states

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2007-04, Vol.40 (8), p.1613-1626
• Main Authors: Prakash, H, Chandra, N, Prakash, R, Shivani
• Format: Article
• Language: English
• Subjects: Classical and quantum physics: mechanics and fields; Exact sciences and technology; Foundations, theory of measurement, miscellaneous theories (including aharonov-bohm effect, bell inequalities, berry's phase); Fundamental areas of phenomenology (including applications); Nonclassical field states; squeezed, antibunched and sub-poissonian states; operational definitions of the phase of the field; phase measurements; Optics; Physics; Quantum information; Quantum mechanics; Quantum optics
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/40/8/012

A scheme of teleporting a superposition of coherent states |alpha and | - alpha using a beam splitter and two phase shifters was proposed by van Enk and Hirota (2001 Phys. Rev. A 64 022313). The authors concluded that the probability for successful teleportation is 1/2. In this paper, it is shown that the authors'scheme can be altered slightly so as to obtain an almost perfect teleportation for an appreciable value of |alpha|2. For |alpha|2 = 5, the minimum of average fidelity, which is the minimum of the sum of the product of probability of occurrence of any case, and the corresponding fidelity is less than 1 by a quantity ~10-4. We also discuss the effect of decoherence on teleportation fidelity. We find that if no photons are counted in both final outputs, the minimum assured fidelity is still non-zero except when there is no decoherence and the information is an even coherent state. For non-zero photon counts, minimum assured fidelity decreases with an increase in |alpha|2 for low noise. For high noise, however, it increases, attains a maximum value and then decreases with |alpha|2. The average fidelity depends appreciably on the information for low values of |alpha|2 only.