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Contextuality-based quantum key distribution with deterministic single-photon sources

Yu Meng, Debashis Saha, Mikkel Thorbjørn Mikkelsen, Clara Henke, Ying Wang, Nikolai Bart, Arne Ludwig, Peter Lodahl, Adán Cabello, Leonardo Midolo

Abstract

Photons are central to quantum technologies, with photonic qubits offering a promising platform for quantum communication. Semiconductor quantum dots stand out for their ability to generate single photons on demand, a key capability for enabling long-distance quantum networks. In this work, we utilize high-purity single-photon sources based on self-assembled InAs(Ga)As quantum dots as quantum information carriers. We demonstrate that such on-demand single photons can generate quantum contextuality. This capability enables a novel protocol for semi-device-independent quantum key distribution over free-space channels. Crucially, our method does not require ideal or perfectly projective measurements, opening a new pathway for robust and practical quantum communication.

Contextuality-based quantum key distribution with deterministic single-photon sources

Abstract

Photons are central to quantum technologies, with photonic qubits offering a promising platform for quantum communication. Semiconductor quantum dots stand out for their ability to generate single photons on demand, a key capability for enabling long-distance quantum networks. In this work, we utilize high-purity single-photon sources based on self-assembled InAs(Ga)As quantum dots as quantum information carriers. We demonstrate that such on-demand single photons can generate quantum contextuality. This capability enables a novel protocol for semi-device-independent quantum key distribution over free-space channels. Crucially, our method does not require ideal or perfectly projective measurements, opening a new pathway for robust and practical quantum communication.
Paper Structure (9 sections, 14 equations, 7 figures, 3 tables)

This paper contains 9 sections, 14 equations, 7 figures, 3 tables.

Table of Contents

  1. Experimental implementation
  2. Optical Setup Summary
  3. Projective Measurement and Detection
  4. The dimension witness
  5. Experimental Data
  6. key analysis for the experimental results for S1 and S2
  7. Application for Quantum Key Distribution
  8. The case when S = S1+S2 > Sc = 32 and S1 < 30
  9. Application for Quantum randomness generation

Figures (7)

  • Figure 1: (a) The architecture of contextuality-based QKD protocol prototype in free space using the hybrid of path and polarization encoding. A photonic crystal waveguide collects the emitted photons from the quantum dot and guides the photons to the shallow etched grating out-couplers in the cold chamber (AutoDry 1000). (b) Experimental result of the HBT experiment: $g^2(0) = 3.6\% \pm 0.2\%.$ It is done by the Hanbury Brown and Twiss (HBT) experiment.
  • Figure 2: Experimental violation of the KCBS inequality using quantum dot single-photon states (red) and weak coherent states (blue) at various average photon numbers $\mu$. For fair comparison, the quantum dot source is assumed to emit exactly one photon per pulse, corresponding to $\mu = 1$. Error bars are estimated using a Monte Carlo method, but are smaller than the marker size and not visible at this scale.
  • Figure 3: Secure key rate analysis for weak-coherent lasers and quantum dot single photon sources with different $S_2$ values, when assuming $S_1$ to be the same as in the single photon source case.
  • Figure S1: The 2d experimental setup
  • Figure S2: The construction of the extended graph from the 5-cycle graph.
  • ...and 2 more figures

Theorems & Definitions (1)

  • proof