In the field of quantum electronics, scientists study the interaction of radiation and matter on the quantum level. Utilizing knowledge from electronics and physics, scientists in this field have made many advancements in optics and radio physics. Machines such as the Light Amplification by Stimulated Emission of Radiation (laser) and the Microwave Amplification by Stimulated Emission of Radiation (maser) are particularly useful in the field of quantum electronics.
Quantum theory is accepted by scientists to be the basic theory of physics that unifies all physical devices. As such, any electronic device may be considered to be a quantum electronic device. Most scientists, however, understand quantum electronic devices to be only those devices that stimulate transitions between quantum energy levels. Lasers and masers are the primary devices used in quantum electronics, as each of these focuses energy into a tight, focused beam. Transistors and superconductors may use the principles of quantum mechanics, but they are not usually considered to be quantum electronic devices.
In quantum electronics, the transitions between quantum energy levels are of particular import. Atoms, molecules and other quantum systems contain excited particles. These systems can only contain certain, strictly defined, amounts of energy. When a system gives off electromagnetic radiation, in the form of light or radio waves, it moves from a higher energy level to a lower one. Lasers and masers can be used to excite these atoms or molecules into higher states of energy.
Lasers are one of the main devices used in quantum electronics. These machines radiate light waves in a focused beam within a narrow range of radiation. This makes the light that a laser emits monochromatic, whereas most light sources emit multiple colors of light, even if the light appears to the eye to contain only one color.
Lasers are important in both research and solving practical problems. The light from a laser does not diffuse heat and lacks an electric charge. A laser can operate within corrosive gases and in a vacuum. They are useful in measuring distance with great accuracy, optical communications and thermonuclear fusion.
Another tool that is commonly used in quantum electronics is the maser. These devices emit microwave radiation in a focused beam. The frequency of these microwaves is stable and does not deteriorate as readily as standard microwaves do. The application of this machine allows communication towers that emit sound waves in the microwave radiation range to send information over great distances with little distortion.