2022/04/25 by Xiao-Fu Peng, Yu-Hang Luo, Peng, Xiao-Fu +13 · 1 citation
Computer Science · Physics and Astronomy · #FOS: Physical sciences #Quantum Information and Cryptography #Quantum Physics (quant-ph) #Quantum and electron transport phenomena #Spectroscopy and Quantum Chemical Studies
paper · pdf · doi:10.48550/arxiv.2204.11656
openalex publication_date 2022/04/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We propose a model to identify the quantum/classical boundary. The model introduces a spontaneous collapse of state superposition: (d)/(dt) ρij =-(i)/(ℏ)[H,ρ]ij-ρij/τij. Different from other collapse models, the collapsing scale τij here does not contain a universal parameter, but is specified by the two states | i⟩ and | j⟩: If each state is \em in principle repeatedly readable (typically by a QND measurement), then τij is the \em potentially needed measuring time to discriminate the two states, and the collapse occurs spontaneously \em without any actual monitoring. Otherwise, τij=∞, which means no collapse and everlasting superposition. This happens if one state is not repeatedly readable, or if the two states cannot possibly be discriminated in a particular circumstance (for example in the Rabi oscillation). Detailed analysis shows that for a "trapped Schrödinger's cat", the superposition of |\rm here ⟩ and | \rm there ⟩ is forbidden if E D ≫ 4πℏ c, and allowed if E D ≤ 4πℏ c, where D is the trap separation and E is the energy gap, which can be estimated with M v2. The model also constrains a "free Schrödinger's cat" to display double-slit interference if pθD≥ 8ℏ, where p= Mv, θ is the angle spanned by the two trajectories, and D is the slit separation. In contrast, this model sets no limit on the coherent length of massless photon, thus the arm of a Michelson interferometer can be arbitrarily long. The spontaneous collapse which we propose can occur for an isolated system, and parallels the decoherence induced by interaction with environment.