Title: Quantum Journal Club:Source-Independent Quantum Random Number Generation,Loss-tolerant measurement-device-independent quantum random number generation
Speaker: Zhu Cao Tsinghua University
Time: 2016-05-05 16:00-2016-05-05 17:00
Venue: MMW-S327


Paper: Source-Independent Quantum Random Number Generation

Authors: Zhu Cao, Hongyi Zhou, Xiao Yuan, and Xiongfeng Ma

Reference: Phys. Rev. X 6, 011020 (2016)


Quantum random number generators can provide genuine randomness by appealing to the fundamental
principles of quantum mechanics. In general, a physical generator contains two parts—a randomness
source and its readout. The source is essential to the quality of the resulting random numbers; hence, it
needs to be carefully calibrated and modeled to achieve information-theoretical provable randomness.
However, in practice, the source is a complicated physical system, such as a light source or an atomic
ensemble, and any deviations in the real-life implementation from the theoretical model may affect the
randomness of the output. To close this gap, we propose a source-independent scheme for quantum random
number generation in which output randomness can be certified, even when the source is uncharacterized
and untrusted. In our randomness analysis, we make no assumptions about the dimension of the source.
For instance, multiphoton emissions are allowed in optical implementations. Our analysis takes into
account the finite-key effect with the composable security definition. In the limit of large data size, the
length of the input random seed is exponentially small compared to that of the output random bit.
In addition, by modifying a quantum key distribution system, we experimentally demonstrate our scheme
and achieve a randomness generation rate of over 5 × 103 bit=s.


Paper: Loss-tolerant measurement-device-independent quantum random number generation

Authors: Zhu Cao, Hongyi Zhou and Xiongfeng Ma

Reference: New J. Phys. 17 125011 (2015)


Quantum random number generators (QRNGs) output genuine random numbers based upon the
uncertainty principle. AQRNGcontains two parts in general—a randomness source and a readout
detector.How to remove detector imperfections has been one of the most important questions in
practical randomness generation.Wepropose a simple solution, measurement-device-independent
QRNG, which not only removes all detector side channels but is robust against losses. In contrast to
previous fully device-independent QRNGs, our scheme does not require high detector efficiency or
nonlocality tests. Simulations show that our protocol can be implemented efficiently with a practical
coherent state laser and other standard optical components. The security analysis of ourQRNG
consists mainly of two parts: measurement tomography and randomness quantification, where several
new techniques are developed to characterize the randomness associated with a positive-operator
valued measure.