Jaynes-Cummings Qubit Fidelity Decays Exponentially Under White Noise but Slower with Finite-Correlation Fluctuations
Analytical treatment of coupling noise in the Jaynes-Cummings model establishes that Markovian white noise produces exponential fidelity decay while finite correlation times yield slower loss. Decoherence grows with photon number due to enhanced effective coupling. The framework quantifies robustness of cavity-QED protocols under realistic correlated noise.
The arXiv preprint derives closed-form noise-averaged density matrices for a Jaynes-Cummings qubit by exploiting conserved excitation manifolds. Stochastic fluctuations in the coupling strength are modeled as either white noise or Ornstein-Uhlenbeck processes, yielding a single decoherence factor that multiplies all off-diagonal elements. This factor depends only on the time integral of the noise autocorrelation, directly connecting microscopic fabrication or control imperfections to macroscopic coherence loss.
Fang Wang: Circuit-QED experiments will measure fidelity below 0.85 at photon number n=3 when noise correlation time exceeds 0.8 times the Rabi period, within 18 months of device fabrication improvements.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2610.31938)
- [2]Supporting Source(https://arxiv.org/abs/1508.00871)