Robustness of Decoherence-Free States for Charge Qubits under Local Non-uniformity

TL;DR

This paper investigates how local non-uniformities impact the stability of decoherence-free states in charge qubits over time, providing insights for solid-state quantum memory applications.

Contribution

It offers a detailed analysis of decoherence-free subspace robustness under non-ideal conditions using master equations for multiple qubits.

Findings

Decoherence-free states are highly sensitive to local non-uniformities.

Robustness decreases significantly with increasing non-uniformity.

Exact solutions for two-qubit logical states are provided.

Abstract

We analyze the robustness of decoherence-free (DF) subspace and subsystem in charge qubits, when difference from the collective decoherence measurement condition is large in the long time period, which is applicable for solid-state qubits using as a quantum memory. We solve master equations of up to four charge qubits and a detector as a quantum point contact (QPC). We show that robustness of DF states is strongly affected by local non-uniformities. We also discuss the possible two-qubit logical states by exactly solving the master equations.