Probing spin entanglement by gate-voltage-controlled interference of current correlation in quantum spin Hall insulators

• Spin entanglement measured all-electrically with quantum spin Hall insulators.
• Step structures of differential noise indicate the concurrence.
• Dephasing effects are also discussed.

We propose an entanglement detector composed of two quantum spin Hall insulators and a side gate deposited on one of the edge channels. For an ac gate voltage, the differential noise contributed from the entangled electron pairs exhibits the nontrivial step structures, from which the spin entanglement concurrence can be easily obtained. The possible spin dephasing effects in the quantum spin Hall insulators are also included.