Quantum complementarity ad infinitum: Switching higher-order coherence from infinity to zero
Phys. Rev. A 112, 063723 – Published 22 December, 2025
DOI: https://doi.org/10.1103/gxzt-164h
Abstract
We reveal a sharp form of complementarity in the Janus state: a coherent superposition of two squeezed vacua. Using a compact generating-function formalism, we derive closed-form expressions for at all orders and introduce squeezing polynomials that factorize the moments and expose phase-dependent scaling. The Janus state operates as a phase-tunable quantum switch for multiphoton correlations: when which-path or which-state information is available (trivial interference), the higher-order coherences reproduce the single-squeezed limit and diverge; when path information is erased and genuine interference from coherent superposition is enabled, multiphoton events are extinguished, driving for all . We obtain a hierarchy of suppression with exponents set by the interference phase and the parity of , and we visualize the mechanism via pronounced Wigner-function negativity. The framework is general and experimentally accessible, enabling engineered nonclassical light with tailored higher-order statistics.