Towards feasible long-distance DI QKD

Device-independent quantum key distribution offers the highest level of information security which can be monitored and verified by users by performing a Bell test. Despite its recent demonstrations, its feasible photonic long-distance realization, which allows one to close the detection loophole, has not yet been proposed. Here, we outline a fully photonic secure DI QKD protocol based on heralded entanglement distribution which allows simultaneous elimination of loopholes in nonlocality tests and high key rates that scale with a square root of channel transmittance (known as twin-field scaling). This makes the protocol suitable for long-range communications, free from the assumption that fully characterized devices are used. The protocol is secure against general attacks performed by an eavesdropper which is limited only by the laws of quantum physics. Our solution is an enabler for secure implementations of a wide range of distributed quantum applications.