On-demand generation of higher-order Fock states in quantum-dot--cavity systems

TL;DR

This paper proposes and compares protocols for on-demand generation of higher-order Fock states in quantum-dot--cavity systems, accounting for realistic loss and dephasing effects, and predicts achievable fidelities above 40%.

Contribution

It introduces new protocols for generating higher-order Fock states in solid-state systems and analyzes their performance considering realistic physical effects.

Findings

Protocols can achieve >40% fidelity for Fock state |5>

Impact of exciton state and polarization on fidelity analyzed

Resonant cavity protocol performs well under realistic conditions

Abstract

The on-demand preparation of higher-order Fock states is of fundamental importance in quantum information sciences. We propose and compare different protocols to generate higher-order Fock states in solid state quantum-dot--cavity systems. The protocols make use of a series of laser pulses to excite the quantum dot exciton and off-resonant pulses to control the detuning between dot and cavity. Our theoretical studies include dot and cavity loss processes as well as the pure-dephasing type coupling to longitudinal acoustic phonons in a numerically complete fashion. By going beyond the two-level approximation for quantum dots, we study the impact of a finite exchange splitting, the impact of a higher energetic exciton state, and an excitation with linearly polarized laser pulses leading to detrimental occupations of the biexciton state. We predict that under realistic conditions, a protocol which keeps the cavity at resonance with the quantum dot until the desired target state is reached is able to deliver fidelities to the Fock state $| 5\rangle$ well above $40\,\%$.