Experimental limit on non-linear state-dependent terms in quantum theory

Understand

We report the results of an experiment that searches for causal non-linear state-dependent terms in quantum field theory.

• Our approach correlates a binary macroscopic classical voltage with the outcome of a projective measurement of a quantum bit, prepared in a coherent superposition state.
• Measurement results are recorded in a bit string, which is used to control a voltage switch.
• Presence of a non-zero voltage reading in cases of no applied voltage is the experimental signature of a non-linear state-dependent shift of the electromagnetic field operator.