Fewer Interfaces, Longer Coherence: Inverting the Multi-Shell Design Rule for Quantum-Information Colloidal Quantum Dots

Abstract Cascaded type-II core/shell/shell colloidal quantum dots are widely studied as a route to extended radiative lifetimes, suppressed Auger losses, and tunable near-infrared emission. To test whether the same architecture remains advantageous for coherence-limited quantuminformation applications, the cascaded core/shell/shell CdSe/CdTe/ZnTe is compared with the conventional core/shell CdSe/ZnTe at fixed core and total radii. The wave functions of the electron and the hole are obtained from a self-consistent Schrödinger-Poisson solve with experimental band offsets and BenDaniel-Duke matching. They enter as inputs to a five-channel Lindblad master equation that includes radiative recombination, two-particle Shockley-Read-Hall non-radiative recombination, optical-phonon pure dephasing, single-particle interface-trap dephasing, and a partial-measurement channel of dimensionless strength η = γ meas T (0) 2 . Three independent geometric sweeps-over core radius, CdTe interlayer thickness, and ZnTe outershell thickness-show that the core/shell/shell architecture underperforms the core/shell architecture in coherence time by a factor of two to three and in measurement fidelity by up to ∆F = 0.16 at η = 1. At the smallest total radius examined, the spatial electron-hole separation ∆r eh is matched between the two architectures to within 2 Å, yet the fidelity gap persists. The gap therefore originates not from the spatial separation that motivated the cascaded design, but from the interface count alone. For coherence-limited applications, interface minimization therefore takes precedence over band-alignment optimization, inverting the design rule established for optical and photovoltaic performance.