Sensitivity of the decay of entanglement of quantum dot spin qubits to the magnetic field

TL;DR

This paper investigates how the decay of entanglement in quantum dot spin qubits is affected by magnetic fields, revealing a transition between two decoherence regimes and proposing a new method for precise magnetic field measurement.

Contribution

It demonstrates the magnetic field dependence of entanglement decay regimes in quantum dot spin qubits and suggests using Bell states for sensitive magnetic field measurements.

Findings

Entanglement decay exhibits two regimes depending on magnetic field strength.

Oscillations in entanglement decay are suppressed at certain magnetic fields.

Proposes Bell states as candidates for precise magnetic field sensing.

Abstract

We study the decay of entanglement of quantum dot electron-spin qubits under hyperfine interaction mediated decoherence. We show that two qubit entanglement of a single entangled initial state may exhibit decay characteristic of the two disentanglement regimes in a single sample, when the external magnetic field is changed. The transition is manifested by the supression of time-dependent entanglement oscillations which are superimposed on the slowly varying entanglement decay related to phase decoherence (which result in oscillatory behaviour of entanglement sudden death time as a function of the magnetic field). This unique behaviour allows us to propose the double quantum dot two-electron spin Bell state as a promising candidate for precise measurements of the magnetic field.