npj Quantum Information, Published online: 21 November 2024; doi:10.1038/s41534-024-00899-6
Researchers propose a multi-particle ‘which-path’ gedanken experiment with a quantum detector. Contrary to conventional ‘which-path’ experiments, the detector maintains its quantum state during interactions with the particles.
They have showed how such interactions can create an interference pattern that vanishes on average, as in conventional ‘which-path’ schemes, but contains hidden many-body quantum correlations. Measuring the state of the quantum detector projects the joint-particle wavefunction into highly entangled states, such as GHZ’s.
Conversely, measuring the particles projects the detector wavefunction into desired states, such as Schrodinger-cat or GKP states for a harmonic-oscillator detector, e.g., a photonic cavity.
This work thus opens a new path to the creation and exploration of many-body quantum correlations in systems not often associated with these phenomena, such as atoms in waveguide QED and free electrons in transmission electron microscopy.
