The Binary-Outcome Detection Loophole

Understand

The detection loophole problem arises when quantum devices fail to provide an output for some of the experimental runs.

• These failures allow for the possibility of a local hidden-variable description of the resulting statistics; even if the correlations obtained from successful runs appear non-local.
• This is of particular significance in device-independent quantum cryptography, where verifiable non-locality is a necessary requirement for the security proof.
• For every scenario characterised by the amount of devices, along with the number of inputs and outputs available to them, there is a detection threshold - if the efficiency of the device falls below this no verification is possible.