Single Microwave Photon Detector
The concept of the photon was developed by Albert Einstein at the beginning of the 20th century to explain the observation of several effects, including the photoelectric effect, which were incompatible with the former wave description of radiation. Photons are the elementary packet of electromagnetic radiation and have a dual particle/wave nature. The discrete particle like character is related to the measurement process, which appears in the "click" that a photomultiplier or a photodiode produces when detecting a high energy photon such as those in the x-ray or optical parts of the spectrum. It should be carefully noted that low frequency radiation like radio is also composed of photons. However, the photon character of RF radiation is usually obscured since energies of individual photons are much lower than the typical thermal energy at room temperature (300K).
For this project, our goal is to build a single photon detector for the microwave frequencies (say 1 – 20 GHz or 109 - 1010 Hz). Such a detector would have numerous applications, for instance the detection of small numbers of nuclear spins or the readout of quantum bits, in astronomical detection and elsewhere.
The development of a quantum sensitive microwave detector would also help shed light on the mechanism that underlies the measurement of a quantum system, where open questions such as the ‘collapse of the wave packet’ remain.