Quantum Breathers in Klein-Gordon Lattice: Non-Periodic Boundary Condition Approach

Abstract:

The presence of classical breathers and two-phonon bound state (TPBS) or quantum breather (QB) state through detailed quantum calculations have already been shown in technologically important ferroelectric materials, such as lithium niobate with antisite niobium charge defects concerning  pinning transition, its control and application. The latter was done in a periodic boundary condition with Bloch function in terms of significant variations of TPBS parameters against impurity, which is related to nonlinearity. In further extension of this work, in a non-periodic boundary condition and number conserving approach, apart from various techniques available, only the temporal evolution of the number of quanta (i.e. phonons) in more sites is detailed in this present investigation for a generalized Klein-Gordon system with applications in ferroelectrics, metamaterials, and DNA. The critical time of redistribution of quanta that is proportional to QB’s lifetime in these materials show different types of behaviour in the femtosecond range, which give rise to the possibilities for making various devices.

Keywords: Quantum Breathers, Klein-Gordon Lattice, Non-Periodic Boundary Condition, Temporal Evolution of Quanta.

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In a non-periodic boundary condition, making our generalized Hamiltonian in Klein-Gordon lattice time dependent, the temporal evolution of quanta shows criticality that is proportional to QB’s lifetime in femtoseconds. The responses in the femtosecond regime of ferroelectrics, metamaterials and DNA are studied together to get an overview of different materials. This effort paves the way for various applications in the THz frequency as well as in quantum computation.

(J. Appl. Phys., Vol. 110 (2011) 124106)