Towards Integrating True Random Number Generation in Coherent Optical Transceivers

Abstract

The integration of quantum communication functions often requires dedicated opto-electronic components that do not bode well with the technology roadmaps of telecom systems. We investigate the capability of commercial coherent transceiver subsystems to support quantum random number generation next to classical data transmission, and demonstrate how the quantum entropy source based on vacuum fluctuations can be potentially converted into a true random number generator for this purpose. We discuss two possible implementations, building on a receiver-and a transmitter-centric architecture. In the first scheme, balanced homodyne broadband detection in a coherent intradyne receiver is exploited to measure the vacuum state at the input of a 90-degree hybrid. In our proof-ofprinciple demonstration, a clearance of >2 dB between optical and electrical noise is obtained over a wide bandwidth of more than 11 GHz. In the second scheme, we propose and evaluate the re-use of monitoring photodiodes of a polarization-multiplexed inphase/quadrature modulator for the same purpose. Time-interleaved random number generation is demonstrated for 10 Gbaud polarizationmultiplexed quadrature phase shift keyed data transmission. The availability of detailed models will allow to calculate the extractable entropy and we accordingly show randomness extraction for our two proof-of-principle experiments, employing a two-universal strong extractor.

Cryptographically strong random number generation using integrated CMOS photodiodes for low-cost microcontroller based applications

“…In the literature, using optical components as quantum entropy source for a TRNG is commonly reported [22,[29][30][31][32][33]. For example, an intradyne receiver is utilized to achieve wide noise bandwidth of 11GHz [22].…”

“…These implementations provide high performance and strong randomness due to the quantum nature of the entropy source. However, they mostly require advanced setups, high perfromance computing units (DSP [22], FPGA [29,30], PC CPU [32], and methods that are not easily available for low-cost embedded system implementations.…”

“…Then various statistical tests are performed for measuring the strength of the generator. As the entropy source thermal noise on electrical components [9,10], phase jitter in oscillators [11][12][13][14],chaos [15,[17][18][19][20], spintronic [21] or optical sources [22] can be utilized. These implementations require advanced setups that require complex instrumentation and cover a large area.…”

Time-interleaved quantum random number generation within a coherent classical communication channel

“…On the other hand, balanced homodyne detectors have been widely adopted in the field of optical communications, and are easily commercially available. Coherent receivers in particular can easily be re-purposed for randomness generation, which allows the integration of a vacuum-based QRNG into optical communication links [Milovančev et al 2020].…”

Quantum RNG Integration in an NG-PON2 Transceiver

“…We have recently demonstrated the multi-purpose use of coherent optics such as balanced receivers or optical I/Q modulators [7] for QRNG, by measurement of the vacuum state through mixing with a local laser field in a balanced homodyne detector configuration. However, coherent component technology is mainly applied to metro and core networks, while direct detection still prevails in short-reach networks by virtue of its cost efficiency.…”