What are Low Noise Cryogenic Microwave Amplifiers?
Low Noise Cryogenic Microwave Amplifiers are Cryogenic cooled low-noise amplifiers (LNAs) and have had a profound impact in science. These amplifiers allow methods of communication with distant spacecraft or probe the history and composition of the universe through radio astronomy. It is also used to study basic phenomena through low-temperature physics research as we have seen with the growth in quantum computing. These devices can achieve noise performance that push beyond the limits of classical physics into the quantum realm. Cryogenics LNA’s find use from low frequencies through several hundreds of gigahertz fo ruse in a variety of technologies. Without cryogenic low noise amplifiers, entire branches of experimental science simply would not exist.
Temperatures that are very cold are not measured in degrees Fahrenheit or Celsius, but in Kelvins. Kelvins use the unit symbol K. Zero degrees Kelvin (0 K) is the theoretically coldest possible temperature. Cryogenic temperatures range much lower; from -150°C to -273° C. The temperature -273° C is the absolute lowest that can be achieved. At this temperature the actions of all molecules stop, causing the molecules to be at the lowest possible state of energy.
Why Do Quantum Computers Require Cryogenic Temperatures?
Instead of using regular bits, quantum computers use quantum bits or “Qubits” which can only be detected at extremely low energy levels and at temperatures close to absolute zero. Qubits are extremely delicate, requiring cryogenic temperatures for stability. This requires cryogenic refrigeration systems with multiple stages of cooling and numerous RF cryogenic cables of significant length, all of which introduce thermal noise, harming the integrity of the qubit.
To be ‘read’, a qubit must be isolated from all possible interference. The cryogenic chambers needed for this function can reach temperatures down to 4mK (milli-Kelvin).
We know that quantum state is extremely fragile, and it requires cryogenic temperatures to reduce atomic movement and provide a vibration-free environment. Cryogenic conditions are required because thermal energy and subsequent vibrations can disturb quantum operations. Thermal energy can also introduce unwanted internal RF transitions. This is where the need for cryogenic RF components arises in quantum computing. Classical electronics and RF circuitry are usually designed to operate at temperatures ranging from -40°C to +80°C. This is a decent operating temperature for most commercial, military, and industrial applications; however, it is nowhere near the cryogenic temperature that is required to keep a quantum system stable. A cryogenic system can require temperatures as low as 4mK (-273 Degrees C).
