A research team at the Low Temperature Laboratory of the Aalto University based in Finland has demonstrated a novel method to detect and amplify weak electromagnetic signals such as microwaves or radio waves almost noiselessly using a nanomechanical oscillator.
Electromagnetic signals can be detected and amplified almost noiselessly using a guitar-string like mechanical vibrating wire. In the ideal case the method adds only the minimum amount of noise required by quantum mechanics. (Credit: Juha Juvonen)
The research team accidently discovered the method when it was trying to cool the nanomechanical oscillator to a temperature close to the absolute zero value of -273° C. The team observed that atoms of the nanomechanical oscillator were resonating in pace in their collective quantum state. At this extreme environment, even nearly macroscopic objects obey the quantum physics laws.
The nanomechanical resonator was produced in connection with a superconducting cavity resonator that swaps energy with the resonator, which in turn amplifies the resonant movement. The research team used a microwave laser as the energy source. The method in its ideal case includes very-low noise needed by quantum mechanics.
The research team has demonstrated the amplification of the microwave radiation at very-low noise based on the quantum resonant motion. Hence, this method is capable of determining very feeble signals. Dr. Francesco Massel explained that the cooling of the nanomechanical oscillator to its quantum ground state weakens a probing signal. However, when the team modifies the microwave laser’s frequency, there is an increase in the probing signal strength.
Mika Sillanpaa, an academy research fellow, stated that the team has fabricated a nearly quantum limited microwave amplifier. Another academy research fellow, Tero Heikkila stated that the simplified design of the amplifier comprising two coupled oscillators can be made possible in any media. The device can be used to determine terahertz radiation by utilizing a cavity with a different structure, Heikkila said. The Aalto method paves the way to the development of some real-life applications with the help of an extensive research.