Quantum Key Distribution

PIC-Based CV-QKD Link Optimizer

Integrated photonic continuous-variable quantum key distribution simulator with Gaussian-modulated coherent states, realistic hardware modeling, and finite-size security analysis

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1.4 Gbps
Key Rate @ 25km
16 GBaud
Symbol Rate
80+ km
Max Distance
0.95
Reconciliation Efficiency

System Architecture

Alice (TX)

GMCS State Preparation

Gaussian Modulation

Quantum Channel

Fiber: 0.2 dB/km

Excess Noise: ξ

Bob (RX)

Homodyne/Heterodyne

Coherent Detection

Collective Attacks

Holevo bound χ_BE

Finite-Size Effects

Parameter estimation penalty

Secret Key Rate

K = β·I_AB - χ_BE

Interactive Tools

Explore CV-QKD system design with our interactive simulators and analyzers

Key Rate Calculator

Calculate secret key rates with adjustable channel parameters, modulation variance, and reconciliation efficiency.

Launch Tool

Link Budget Analyzer

PIC loss budget analysis with grating couplers, waveguides, splitters, and LO routing losses.

Launch Tool

Noise Analysis

Channel noise, excess noise sensitivity, and shot noise unit (SNU) characterization.

Launch Tool

Detector Modeling

Quantum efficiency, electronic noise, and detector bandwidth effects on key rate.

Launch Tool

Distance Analysis

Key rate vs distance curves with metropolitan and long-haul deployment scenarios.

Launch Tool

Security Analysis

Finite-size security analysis with composable security bounds and attack models.

Launch Tool

Technical Features

GMCS Protocol

  • Gaussian-modulated coherent states with tunable variance
  • Homodyne and heterodyne detection modes
  • Optional squeezed state enhancement
  • Reverse reconciliation for extended range

PIC Hardware Model

  • Grating coupler losses: 3-6 dB/facet
  • Waveguide propagation: 0.5-2 dB/cm
  • Component losses: splitters, interferometers
  • LO routing and power splitting analysis

Security Framework

  • Asymptotic key rate calculations
  • Finite-size effects with composable security
  • Collective attack bounds (Holevo χ_BE)
  • Parameter estimation overhead

Analysis Capabilities

  • Distance-dependent key rate optimization
  • Sensitivity analysis for all parameters
  • CSV export for further analysis
  • Reproducible results with metadata logging

Key Equations

Secret Key Rate

K = β · IAB - χBE

β: reconciliation efficiency, I_AB: mutual information, χ_BE: Holevo bound

Mutual Information (Homodyne)

IAB = ½ log2[(VA + 1) / (1 + χtot)]

V_A: modulation variance, χ_tot: total noise

System Transmittance

T = ηPIC × ηfiber × ηdet × ηLO

Total transmission including all loss sources

Total Channel Noise

χtot = (1 - T) / T + ξ

Channel-added noise plus excess noise ξ

Documentation

Theory

CV-QKD fundamentals and security proofs

API Reference

Complete Python API documentation

Tutorials

Step-by-step learning guides

Examples

Production code examples

Performance Results

Key Rate vs Distance (Standard Configuration)

Distance Key Rate (bits/symbol) Throughput @ 16 GBaud Use Case
10 km ~0.15 2,400 Mbps Data Center
25 km ~0.089 1,424 Mbps Metropolitan
50 km ~0.024 384 Mbps City-Wide
80 km ~0.003 48 Mbps Long-Haul

* Standard config: β=0.95, V_A=4 SNU, ξ=0.01 SNU, η_det=0.6, fiber loss=0.2 dB/km

Design Trade-offs

PIC Loss Impact

1 dB PIC loss ≈ 5% detector quantum efficiency loss in effective key rate.

Excess Noise Critical

0.005 SNU excess noise change roughly halves achievable transmission distance.

Squeezing Limited

Squeezing benefit limited to <2 dB due to losses in integrated photonic systems.