Fewer interfaces, longer coherence: inverting the multi-shell design rule for quantum-information colloidal quantum dots
Year: 2026
Type: article
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 quantum-information 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, acoustic-phonon pure dephasing, single-particle interface-trap dephasing, and a measurement-induced dephasing channel of dimensionless strength η = γ meas T 2 ( 0 ) . Three independent geometric sweeps—over core radius, CdTe interlayer thickness, and ZnTe outer-shell 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 coherence-preservation fidelity by up to Δ F = 0.16 at η = 1 . At the smallest total radius examined, the spatial electron–hole separation Δ 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. For coherence-limited applications in trap-dominated structures with compositionally sharp interfaces, interface minimization therefore takes precedence over band-alignment optimization, inverting the design rule established for optical and photovoltaic performance.
Source: Quantum Science and Technology
Author: Fatih Koç
Institution: Ahi Evran University
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,895
OpenAlex ID: W7203976709
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