Quantum learning of coherent states

Understand

We develop a quantum learning scheme for binary discrimination of coherent states of light.

• This is a problem of technological relevance for the reading of information stored in a digital memory.
• In our setting, a coherent light source is used to illuminate a memory cell and retrieve its encoded bit by determining the quantum state of the reflected signal.
• We consider a situation where the amplitude of the states produced by the source is not fully known, but instead this information is encoded in a large training set comprising many copies of the same coherent state.