Exploring entanglement resource in Si quantum dot systems with operational quasiprobability approach

TL;DR

This paper investigates the robustness of quantum entanglement in silicon quantum dot systems under charge noise using an operational quasiprobability approach, revealing that entanglement resources remain relatively stable despite noise-induced operational degradation.

Contribution

It introduces the use of marginal operational quasiprobability to characterize entanglement in noisy silicon quantum dot systems, demonstrating its invariance under charge noise.

Findings

Entanglement pattern remains stable despite charge noise.

Charge noise significantly degrades operational fidelity.

Operational quasiprobability effectively detects entanglement under noise.

Abstract

We characterize the quantum entanglement of the realistic two-qubit signals that are sensitive to charge noises. Our working example is the time response generated from a silicon double quantum dot (DQD) platform, where a single-qubit rotation and a two-qubit controlled-NOT operation are conducted sequentially in time to generate arbitrary entangled states. In order to characterize the entanglement of two-qubit states, we employ the marginal operational quasiprobability (OQ) approach that allows negative values of the probability function if a given state is entangled. While the charge noise, which is omnipresent in semiconductor devices, severely affects logic operations implemented in the DQD platform, causing huge degradation in fidelity of unitary operations as well as resulting two-qubit states, the pattern in the OQ-driven entanglement strength turns out to be quite invariant, indicating that the resource of quantum entanglement is not significantly broken though the physical system is exposed to noise-driven fluctuations in exchange interaction between quantum dots.