Fig. 1: Experimental setup for characterizing the quantum dot emission.
From: Deterministic and highly indistinguishable single photons in the telecom C-band
An InAs/InAlGaAs quantum dot (QD) in a circular bragg grating resonator (CBG) inside a cryostat at 4 K is used for photon generation. The QD is excited optically using a ps-laser that is tunable in wavelength and linewidth (repetition rate τrep = 80 MHz). The laser is sent to the QD through a 90:10 beam splitter (BS). The QD emission can be spectrally filtered (see Supplementary Fig. 4 for a more detailed sketch of the setup). In order to assess the properties of the photons emitted from the QD, we perform a series of measurements. a The generated photons are sent to a spectrometer for spectral characterization. b, c The generated photons pass an active demultiplexing setup, where consecutively emitted photons can be deterministically separated into two spatial modes using a 40 MHz electro-optical modulator (EOM) and a polarizing beam splitter (PBS). For the autocorrelation measurement (b), the photons are then sent to one input of a fiber-based 50:50 beam splitter (whilst the second input is blocked). The output statistics are then measured using time taggers connected to superconducting nanowire single-photon detectors (SNSPDs). For the measurement of two-photon interference (c), consecutively emitted photons are sent to either input of the BS and coincidences are recorded.
