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DWC Seminar Series 2017

21 November 2017

The Dodd-Walls Centre is proud to present a series of seminars hosted by our themes on different topics and everyone is welcome to attend.   

Friday’s Photonic Sensors and Imaging (QMI) seminar is presented by Gabriel A. Santamaria-BotelloUniversidad Carlos III de Madrid, Leganés, Spain.   This presentation will also be available via Zoom. 

Title:      Cosmic microwave background and microwave up-conversion: Limitations and quantum noise

When:    Friday 24 November, 12noon (sharp) 

Venues:  303.610 Auckland

    Room 312, 3rd floor, Science III, University of Otago (please note the change of venue!)

    Anyone can join remotely via Zoom ID # 325 816 342


A radiometer concept based on the photonic up-conversion of microwave radiation into the optical domain within nonlinear whispering-gallery mode (WGM) resonators is proposed. Since the parametric up-conversion is intrinsically noiseless for the anti-Stokes generated sideband, this detection technique can potentially achieve a high sensitivity even at room temperature. This technique finds applications in radio astronomy such as the observation of the temperature and spectral characteristics of the cosmic microwave background (CMB) upon which many cosmological predictions rely. The sensitivity of the radiometer is limited by thermal noise coupled to the WGM resonator, and by quantum noise originated from low photon conversion efficiencies. Thermal noise can be reduced by radiatively cooling the microwave mode, whereas high efficiencies can be achieved by engineering the cavities such that the modal overlap is maximized. Other challenges such as the realization broadband up-conversion have to be overcome in order to observe the CMB with high temperature sensitivity. Thus, on the basis of a thermal and quantum noise study, the sensitivity limitations of the radiometer are discussed, while some approaches currently under research to achieve efficient and broadband up-conversion are presented.