No, quantum field theory (QFT) and the concept of photons are not based on the existence of an ether. The notion of an ether, which was once proposed as a medium through which electromagnetic waves were thought to propagate, has been largely abandoned in modern physics.
In quantum field theory, the photon is considered a fundamental particle and the quantum carrier of the electromagnetic force. It is not tied to any concept of an ether or a medium for its existence or propagation. Instead, QFT describes the behavior of photons (and other particles) as excitations of their respective fields, which pervade all of spacetime. These fields are not tied to any medium but are fundamental properties of the quantum field theory framework.
According to the principles of QFT, photons are quantized excitations of the electromagnetic field. They are described as wave-particle duality, meaning they exhibit both wave-like and particle-like properties. Photons are massless particles that travel at the speed of light in vacuum, and their behavior is governed by quantum mechanics.
The concept of an ether was introduced in attempts to explain the propagation of electromagnetic waves in the 19th century. However, with the development of special relativity and the experiments of Michelson and Morley in the late 19th century, the existence of a luminiferous ether was shown to be unnecessary and inconsistent with experimental observations. Special relativity provided a new framework for understanding the behavior of light and electromagnetic waves without invoking an ether.
Since then, the understanding of photons and electromagnetic waves has evolved based on the principles of quantum mechanics and quantum field theory, which do not rely on the concept of an ether. Instead, these theories describe the behavior of particles and fields in a relativistic and quantum mechanical framework, providing a more comprehensive and successful description of the electromagnetic interactions.