The way quantum propulsion works is it aims to generate it's thrust by way of manipulating the quantum vacuum which is a concept in quantum field theory in which virtual particles are constantly popping in and out of existence.
Essentially it extracts energy from the seemingly empty space to create a propulsive force which is achieved by influencing the quantum vacuum with electromagnetic fields and potentially through specially designed materials which interact with the virtual particles that create a net momentum which pushes the spacecraft forward.
An example of propulsion force is a car engine that propels a car forward or a rocket engine that launches a spacecraft into space.
To create propulsion the burning of fuel creates hot gas which is then expelled through a nozzle to generate the thrust needed to propel the rocket forward.
Any exact which pushes an object or something to move including a car engine driving a vehicle or even a person that is walking by pushing off the ground are also examples of propulsion.
When you drive your car the engine burns fuel which turns makes the engine run and turn the engines crankshaft to engage with the transmission to propel the car forward down the road.
Essentially propulsion is simply the act of driving an object forward or pushing an object forward.
When you pedal a bicycle you're propelling the bicycle forward with your feet on the pedals.
A propulsion system also uses a source of power to create thrust.
This thrust then pushes against an object like a car, airplane, rocket etc to move it forward.
The amount of thrust that is created depends on the mass flow through the engine and also the exit velocity of the gas.
Walking, flying and airplane, launching a rocket and driving a car or other vehicle are all examples of propulsion.
There are several types of propulsion systems which include rocket propulsion systems, electric propulsion systems, gas turbine engines and internal combustion engines.