Local measurements can alter long-range correlations in gapless quantum matter. We propose a theory of weakly-monitored Tomonaga-Luttinger liquids, a broad class of quantum critical states in one dimension. In order to address the intrinsic randomness of the measurement record, we develop a replica instanton calculation to study Born-averaged observables. We find that when measurements are relevant, average correlators of density and phase fluctuations decay at long distances as universal power laws with logarithmic corrections, a feature we argue is peculiar to measurement-induced randomness. We characterize the full multifractal spectrum of moments of correlations functions, revealing broad, strongly non-gaussian fluctuations across the ensemble of post-measurement states. We support these analytic results with matrix-product-state calculations, and provide a general picture of measurement-altered criticality for ground states described by 1+1d conformal field theories. Our results establish that physical measurements alter critical quantum states in a manner that lies beyond both forced measurements and conventional critical scaling.
The impact of projective measurements on a many-body quantum state is tightly linked to its underlying entanglement structure. Critical states are particularly sensitive, as long-range entanglement allows local measurements to have global consequences. This has been extensively studied in the context of critical states...
The critical behavior of a system near a continuous phase transition is commonly characterized by power laws and a set of universal critical exponents. Yet universality at phase transitions has even more fundamental manifestations. It dictates that all observables follow universal scaling functions, which may extend be...
Paul Paquiez, Géraud Dupuy, Maxime Allemand et al.· 0 citations
Entanglement phase transitions driven by quantum measurements have emerged as a central paradigm in open quantum many-body physics. Such phase transitions are well established for systems with finite local Hilbert-space dimensions, such as qubits and fermions, while their realization in bosonic systems with unbounded l...
I. Komissarov, Emanuele G. Dalla Torre, Ahana Chakraborty· 0 citations
Weak measurements have been predicted to dramatically alter universal properties of quantum critical wave functions, though experimental validation remains an open problem. Here we devise a practical scheme for realizing measurement-altered criticality in a chain of Rydberg atoms tuned to Ising and tricritical Ising ph...
Stephen Naus, Yue Liu, S. Murciano et al.· Physical Review Letters· 0 citations
Conformal field theories (CFTs) feature prominently in high-energy physics1,2, statistical mechanics3 and condensed matter4, 5–6. For example, CFTs govern emergent universal properties of systems tuned to quantum phase transitions4,7, including their entanglement, correlations and low-energy excitation spectra. Much of...
Xiang-Kai Sun, Yuan Le, Stephen Naus et al.· Nature· 19 citations· ⚡1
We find that the measurement-induced phase transition generated by deterministic global measurements, previously observed in the integrable transverse-field Ising model (TFIM), persists in non-integrable variants of the same. To address this question, we consider the TFIM with longitudinal field and the axial next-near...
Paranjoy Chaki, P. Nandi, S. Dasgupta et al.· 0 citations
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