Parametric Amplification of a Terahertz Quantum Plasma Wave

TL;DR

This paper demonstrates the parametric amplification of terahertz Josephson plasma waves in cuprate superconductors using their inherent cubic tunneling nonlinearity, enabling potential applications in quantum terahertz devices.

Contribution

It introduces a method to amplify terahertz plasma waves in layered superconductors via parametric processes, leveraging their nonlinear tunneling properties.

Findings

Terahertz JPWs can be parametrically amplified in cuprate superconductors.

Amplification depends on the phase relationship between pump and seed waves.

Potential for squeezing phase fluctuations or creating single-photon terahertz devices.

Abstract

Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support weakly damped plasma waves, involving oscillatory tunneling of the superfluid between capacitively coupled planes. Such Josephson plasma waves (JPWs) are also highly nonlinear, and exhibit striking phenomena like cooperative emission of coherent terahertz radiation, superconductor-metal oscillations and soliton formation. We show here that terahertz JPWs in cuprate superconductors can be parametrically amplified through the cubic tunneling nonlinearity. Parametric amplification is sensitive to the relative phase between pump and seed waves and may be optimized to achieve squeezing of the order parameter phase fluctuations or single terahertz-photon devices.