  Quantum entanglement between distant qubits is an important feature of
quantum networks. Distribution of entanglement over long distances can be
enabled through coherently interfacing qubit pairs via photonic channels. Here,
we report the realization of optically generated quantum entanglement between
electron spin qubits confined in two distant semiconductor quantum dots. The
protocol relies on spin-photon entanglement in the trionic $\Lambda$-system and
quantum erasure of the Raman-photon path. The measurement of a single Raman
photon is used to project the spin qubits into a joint quantum state with an
interferometrically stabilized and tunable relative phase. We report an average
Bell-state fidelity for $|\psi^{(+)}\rangle$ and $|\psi^{(-)}\rangle$ states of
$61.6\pm2.3\%$ and a record-high entanglement generation rate of 7.3 kHz
between distant qubits.
