Enhancing Extractable Quantum Entropy in Vacuum-Based Quantum Random Number Generator.

Xiaomin Guo,Ripeng Liu,Pu Li,Chen Cheng,Mingchuan Wu,Yanqiang Guo

doi:10.3390/e20110819

Abstract

Information-theoretically provable unique true random numbers, which cannot be correlated or controlled by an attacker, can be generated based on quantum measurement of vacuum state and universal-hashing randomness extraction. Quantum entropy in the measurements decides the quality and security of the random number generator (RNG). At the same time, it directly determines the extraction ratio of true randomness from the raw data, in other words, it obviously affects quantum random bits generating rate. In this work, we commit to enhancing quantum entropy content in the vacuum noise based quantum RNG. We have taken into account main factors in this proposal to establish the theoretical model of quantum entropy content, including the effects of classical noise, the optimum dynamical analog-digital convertor (ADC) range, the local gain and the electronic gain of the homodyne system. We demonstrate that by amplifying the vacuum quantum noise, abundant quantum entropy is extractable in the step of post-processing even classical noise excursion, which may be deliberately induced by an eavesdropper, is large. Based on the discussion and the fact that the bandwidth of quantum vacuum noise is infinite, we propose large dynamical range and moderate TIA gain to pursue higher local oscillator (LO) amplification of vacuum quadrature and broader detection bandwidth in homodyne system. High true randomness extraction ratio together with high sampling rate is attainable. Experimentally, an extraction ratio of true randomness of 85.3% is achieved by finite enhancement of the laser power of the LO when classical noise excursions of the raw data is obvious.

Highlights

Randomness is one vital ingredient in modern information science, in the regime of both classical and quantum [1,2], since encryption is founded upon the trust in random numbers [3,4,5]
An extraction ratio of true randomness of 85.3% is achieved by finite enhancement of the local oscillator (LO) power when classical noise excursions of the raw data is obvious and the extracted random sequences passed the NIST (National Institute of Standards and Technology), Diehard and the TestU01 tests
Single-mode continuous-wave laser beam from the laser incident into one port of the beamsplitter and acts as the LO, while the other port was blocked to ensure that only the vacuum state could enter in

Summary

Introduction

Randomness is one vital ingredient in modern information science, in the regime of both classical and quantum [1,2], since encryption is founded upon the trust in random numbers [3,4,5]. In the past two decades, there has been tremendous development for various types of quantum RNG [6,7,8,9,10,11,12,13,14,15] Among these proposals, random number generation based on homodyne measurement of quantum vacuum state is especially appealing in practice since highly efficient photodiodes working at room temperature can be applied [11]. Vacuum state is a pure quantum state with the lowest energy and independent of any external physical quantities. It cannot be correlated or controlled by an attacker, unique random numbers can be yielded by measuring

Results

Discussion

Conclusion