Silicon photonics interfaced with integrated electronics for 9 GHz measurement of squeezed light

Photonic quantum technology can be enhanced by monolithic fabrication of both the underpinning quantum hardware and the corresponding electronics for classical readout and control. Here, by interfacing complementary metal–oxide–semiconductor (CMOS)-compatible silicon and germanium-on-silicon nanophotonics with silicon-germanium integrated amplification electronics, we curtail total capacitance in a homodyne detector to enhance the speed performance of quantum light measurement. The detector has a 3 dB bandwidth of 1.7 GHz, is shot-noise limited to 9 GHz and has a minaturized required footprint of 0.84 mm2. We show that the detector can measure the continuous spectrum of squeezing from 100 MHz to 9 GHz of a broadband squeezed light source pumped with a continuous-wave laser, and we use the detector to perform state tomography. This provides fast, multipurpose, homodyne detectors for continuous-variable quantum optics, and opens the way to full-stack integration of photonic quantum devices. A silicon-germanium integrated homodyne detector with a footprint of 0.84 mm2 is fabricated to enhance the speed performance of quantum light measurement. It can measure the spectrum of squeezing from 100 MHz to 9 GHz of a squeezed light source.