Low Noise Balanced Homodyne Detector for Quantum Noise Measurement

This is the authors' abstract. We don't add key points for this paper.

The research of quantum noise in the interaction of laser and atoms plays a critical role in quantum optical experiments. The measurement of quantum noise is mainly based on the balanced homodyne detection method. Here, we reported a balanced homodyne detector with low noise, high gain, and high common-mode rejection ratio (CMRR) at the wavelength of 795 nm. By optimizing the selection of components and printed circuit board (PCB) layout, a minimum electronic noise of −96.7 dBm is obtained. Over the range of 1 MHz to 5 MHz, we get a flat CMRR above 59 dB and a linear gain regime, which can enable a shot noise measurement with the laser power of100~μ w. The developed detector can be used in quantum coherent experiments with a weak probe laser of power down to tens of microwatts.