Integrated Differential Conjugate Homodyne Detection for Quantum Random Number Generation

TL;DR

This paper presents an on-chip quantum random number generator using a novel differential conjugate homodyne detection method with integrated photonics and circuits, achieving high noise clearance and validated by standard randomness tests.

Contribution

It introduces a new differential amplifier configuration for conjugate homodyne detection in QRNG, combining integrated photonics and analog circuits for improved performance.

Findings

Achieved 25.6 dB shot noise clearance

Realized 69 dB common mode rejection ratio

Validated randomness with NIST tests

Abstract

In this work, we perform on-chip quantum random number generation (QRNG) that uses a novel differential amplifier configuration for conjugate homodyne detection. Leveraging separate integrated photonics and integrated analog circuit platforms, we present an alternative method for QRNG. This approach exploits the observable $\hat{\text{Z}}$, derived from the sum of squared conjugate quadrature distributions which we compare to the traditional single quadrature approach. Utilizing this method, we report a shot noise clearance (SNC) of 25.6 dB and a common mode rejection ratio (CMRR) of 69 dB for our homodyne detection system. We used a variety of design tools to model and predict performance and compare results with our measurements. The realization of our QRNG system consists of a 90{\deg} optical hybrid, a dual differential transimpedance amplifier (TIA), and a field-programmable gate array (FPGA) used for the real-time post-processing to produce a uniform random bitstream. The randomness extraction is implemented using a Toeplitz hashing algorithm and is validated by the National Institute of Standards and Technology (NIST) randomness test suites.