Measurement-Induced Phase Transitions: Universal Entanglement Scaling at Quantum Criticality — E8 Intelligence Research

FINDING: Measurement-induced phase transitions (MIPT) in quantum systems reveal a sharp entanglement phase boundary driven by the competition between unitary evolution and projective measurements, with critical points often characterized by universal exponents and effective central charges. | MATH: The MIPT is typically studied via the entanglement entropy \(S = -\text{Tr}(\rho_A \ln \rho_A)\) scaling as \(S \sim \frac{c}{6} \ln L\) at criticality (for 1+1D conformal field theory), where \(c\) is the effective central charge. The critical measurement rate \(p_c\) separates volume-law (\(S \propto L\)) from area-law (\(S \propto \text{const}\)) phases. For Clifford circuits, the transition is in the percolation universality class with \(c = 0\) (or \(c = \ln 2\) for Haar random circuits). The "1/(2π)" appears in the context of the quantum Zeno effect: for a system measured at rate \(\gamma\), the effective Hamiltonian is \(H_{\text{eff}} = H - i \frac{\gamma}{2} \sum_m |m\rangle\langle

Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com