Cyclotron emission imaging of quantum Hall devices

The current state of highly sensitive terahertz imaging microscopes is reported in the context of applications for cyclotron emission studies of quantum Hall devices. Without external excitation other than the transport current, the microscope maps the distribution of nonequilibrium electrons generated in quantum devices by detecting weak cyclotron emission. Firstly, we present the imaging results to discuss the origin of nonequilibrium electrons. Finally, we describe our attempts towards photon counting terahertz microscope with quantum-dot photon detectors utilizing single electron transistors.