Quantum Coherence and Pairing Mechanisms in ...

Quantum Coherence and Pairing Mechanisms in Superconductors

Author Name : Dr. Abhijit Sen

ABSTRACT Superconductivity is a quantum state of matter with zero electrical resistance and the expulsion of magnetic fields. It captivates scientists due to its complex mechanisms and diverse applications. At the core of this phenomenon are two connected processes: electron pairing and quantum coherence. The traditional view, based on the Bardeen-Cooper-Schrieffer (BCS) theory, posits that pairing results from phonon-mediated interactions in conventional metals.However, the emergence of high-temperature and unconventional superconductors, including cuprates, iron-based compounds, heavy fermion systems, and organic materials, has uncovered a variety of pairing mechanisms that often involve spin fluctuations, strong electronic correlations, and multiband effects. This article looks at the evolution of concepts and theoretical foundations of superconductivity, focusing on how electron pairing creates a coherent quantum condensate. It examines the role of coherence in effects like the Meissner effect, Josephson effect, and superconducting qubits. The review also discusses the difficulties in maintaining coherence in complex systems and the search for room-temperature superconductors. By combining insights from studies published up to 2015, it emphasizes both the fundamental physics and future prospects of superconductivity, offering a clear understanding of how quantum coherence and pairing mechanisms shape this transformative phenomenon in condensed matter physics.