Source experimental setup – DI QRNG. (a) Entanglement source: Time-energy entangled photon pairs are generated from a Ti:PPLN waveguide pumped by a pulsed laser with a duration of 5 ns, separated by a PBS. (b) Measurement device: Photons are passively selected to measure Tδ or Dδ by a 90:10 beam splitter (BS) after being coupled to the fibers at Alice and Bob sides. computer, polarization controller; FI, filter; C-BG, Bragg grating; OC, optical circular; SNSPD superconducting nanowire single-photon detector; and TDC, a time-to-digital converter. credit: advanced photonics (2023). DOI: 10.1117/1.AP.5.3.036003
Quantum random number generators (QRNGs) produce true randomness based on the unpredictability inherent in quantum mechanics. They have important applications in quantum information processing and computation tasks. In practice, any defect or inaccurate characterization of quantum source devices in a real application greatly affects the security and generation rate of QRNGs, and may even lead to the disappearance of quantum randomness.
Device-independent (source-DI) QRNGs work with unreliable sources but well-characterized measuring devices, to positively address these issues.
As stated in advanced photonicsRecently, researchers from Nanjing University proposed and experimentally demonstrated a secure and fast-source DI QRNG protocol that is simple and effective for practical implementation. The DI QRNG source is realized in this work by a single photon detection technique with the help of entangled photons.
The random numbers are extracted through a process that measures the arrival time of a photon from a pair of entangled time-energy photons. The time-energy entangled pairs of photons are produced by a spontaneous parametric conversion (SPDC) process.
The researchers were able to confirm the scheme’s security by validating the time-energy entanglement by observing non-local dispersion cancellation. To improve security, they use a modified entropy uncertainty relationship to quantify randomness, taking into account a well-known problem of limited measurement range.
They report a safe generation rate of random bits of 4 megabits per second (Mbps), which they note can reach the gigabit-per-second level with advanced single-photon detectors, due to its faster detection speed and lower temporal resolution. Based on the PPLN waveguide SPDC source, the DI QRNG source they realized can be further developed as an integrated chip-scale device by exploring on-chip photon generation, processing and detection technologies.
According to corresponding author Yan Xiaogong, a professor at Nanjing University, “Compared to many existing semi-DI QRNGs, our work achieves an excellent balance of safety, speed, and practicality.” He adds, “This research paves the way for practical applications of secure quantum information tasks and promotes the development of high-performance, high-security quantum random number generators.”
more information:
Ji-Ning Zhang et al, Realization of a source-independent quantum random number generator by non-local dispersion cancellation, advanced photonics (2023). DOI: 10.1117/1.AP.5.3.036003
the quote: Quantum Random Number Generator Works Safely and Hardware Independent Source (2023, May 17) Retrieved May 17, 2023 from https://phys.org/news/2023-05-quantum-random-generator-independently-source.html
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