Impact of imperfect homodyne detection on measurements of vacuum states shot noise

Quantum random number generators (QRNGs) are currently in high demand across a large number of cryptographic applications as secure sources of true randomness. In this work, we characterize the conditions from which randomness can be extracted in a QRNG based on homodyne measurements of vacuum fluctuations by assessing the impact of experimental limitations, such as the digitizer resolution or the presence of excess local oscillator (LO) noise due to an unbalanced detection. Moreover, we propose an estimation method to quantify the excess entropy contribution introduced by an unbalanced detection and analyze the implementation of the post-processing algorithm. Finally, we submitted the generated numbers to a set of statistical tests to assess the quality of its output randomness and verified that it passes the standard libraries.

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“…where n is the filter-order, and ∆ f is the detector's bandwidth [36]. In its turn, the strong coherent laser signal can be described as:…”

Section: Theoretical Descriptionmentioning

confidence: 99%

“…where k B is the Boltzmann constant, T the temperature, R the load resistance of the TIA, and RIN represents the average relative intensity noise (RIN) over the detector's bandwidth [36], the autocovariance function can be calculated through Equations ( 3) and (6) as:…”

Section: Theoretical Descriptionmentioning

confidence: 99%

Characterization of a Quantum Random Number Generator Based on Vacuum Fluctuations

et al. 2021

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“…These imperfections can be minimised by fine-tuning the coupling of each photodiode to ensure the detector remains balanced. A full analysis of the imperfect case can be found in references [30,31].…”

Section: Homodyne Theory and Design Considerationsmentioning

confidence: 99%

Shot-Noise Limited Homodyne Detection for MHz Quantum Light Characterisation in the 2 μm Band

Biele,

Tasker,

Silverstone

et al. 2021

Preprint

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Characterising quantum states of light in the 2 µm band requires high-performance shot-noise limited detectors. Here, we present the characterisation of a homodyne detector that we use to observe vacuum shot-noise via homodyne measurement with a 2.07 µm pulsed mode-locked laser. The device is designed primarily for pulsed illumination. It has a 3 dB bandwidth of 13.2 MHz, total conversion efficiency of 58% at 2.07 µm and a common-mode rejection ratio of 48 dB at 39.5 MHz. The detector begins to saturate at 1.8 mW with 9 dB of shot-noise clearance at 5 MHz. This demonstration enables the characterisation of megahertz-quantum optical behaviour in the 2 µm band.

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“…In [9], the authors studied the relative contributions of different sources of noise to the final observed excess noise and their subsequent impact on the security of the protocol, in the case of a balanced optical system. Meanwhile, in [24][25][26], the authors studied the impact of different receiver imbalances on multiple parameters of the output voltage of the receiver. Nevertheless, the role of device imperfections on the performance and security of a heterodyne based LLO CV-QKD transmission system has not been explored.…”

Section: Introductionmentioning

confidence: 99%

Impact of receiver imbalances on the security of continuous variables quantum key distribution

Pereira

Almeida

Facão

et al. 2021

EPJ Quantum Technol.

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Continuous-variable quantum key distribution (CV-QKD) provides a theoretical unconditionally secure solution to distribute symmetric keys among users in a communication network. However, the practical devices used to implement these systems are intrinsically imperfect, and, as a result, open the door to eavesdropper attacks. In this work, we show the impact of receiver device imperfections on the estimated channel parameters, performance and security of a CV-QKD system. The presented results show that, due to the erroneously estimated channel parameters, non-monitored imbalances can pose a security risk or even reduce the system’s performance. Our results show the importance of monitoring these imbalances and hint at the possibility of compensating for some receiver imbalances by tuning other components.

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Impact of imperfect homodyne detection on measurements of vacuum states shot noise

Cited by 18 publications

References 22 publications

Characterization of a Quantum Random Number Generator Based on Vacuum Fluctuations

Characterization of a Quantum Random Number Generator Based on Vacuum Fluctuations

Shot-Noise Limited Homodyne Detection for MHz Quantum Light Characterisation in the 2 μm Band

Impact of receiver imbalances on the security of continuous variables quantum key distribution

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