We analyze the one-dimensional potential barrier scattering problem of two-mode squeezed vacuum state and entangled coherent state. We show that the entanglement of both the scattering states exhibits a parabolic relation with the transmission coefficient of the barrier, and valley of the parabola corresponds with a semi-anti-semi-permeable barrier. In addition, the entanglement of the former has a similar parabolic relation with the incident squeezed factor, and the entanglement of the latter has a linear relation with the incident entanglement. The fidelities of both the scattering states increase as the transmission coefficient increases, but the former decreases as the incident squeezed factor increases and the latter decreases as the incident module of coherent state increases.
The struggle of the hour in quantum computing research is achieving effective suppression of the error mechanisms induced by the interaction of external radiation with superconducting quantum devices. Despite the rapid advancements in quantum error correction (QEC) of recent years, radiation-induced faults are yet to be fully addressed. These events are known to be the cause of simultaneous correlated defects in qubits that lie onto a single substrate, ultimately jeopardising QEC code effectiveness.
In this paper, we propose to selectively combine substrate-level phonon barriers and QEC interleaving via a planar-mesh tiling algorithm, TETRIS-Q, reaching efficient and effective suppression of radiation events. Our cross-layer solution comes at no extra cost in terms of QEC code execution or decoding time. We model and simulate radiation-induced transient faults over a plethora of barrier and QEC interleaving configurations. Through more than 51 million quantum circuit simulations, we show peak logical error reductions of more than
99.8%, together with an
80% reduction of the observable transient duration with permeable barriers. We find that sparser tiling can reach comparable performance to single qubit tiling, prompting cost reductions of upwards of
87% in barrier tracing. By leveraging independent QEC code interleaving, we measure up to one order of magnitude average logical error rate reductions without the use of permeable barriers, and up to three orders of magnitude with the joint usage of barriers.