Universität zu Köln

Minoguchi, Y., Rabl, P. and Buchhold, M. (2022). Continuous gaussian measurements of the free boson CFT: A model for exactly solvable and detectable measurement-induced dynamics. SciPost Phys., 12 (1). AMSTERDAM: SCIPOST FOUNDATION. ISSN 2542-4653

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Abstract

Hybrid evolution protocols, composed of unitary dynamics and repeated, weak or projective measurements, give rise to new, intriguing quantum phenomena, including entanglement phase transitions and unconventional conformal invariance. Defying the complications imposed by the non-linear and stochastic nature of the measurement process, we introduce a scenario of measurement-induced many body evolution, which possesses an exact analytical solution: bosonic Gaussian measurements. The evolution features a competition between the continuous observation of linear boson operators and a free Hamiltonian, and it is characterized by a unique and exactly solvable covariance matrix. Within this framework, we then consider an elementary model for quantum criticality, the free boson conformal field theory, and investigate in which way criticality is modified under measurements. Depending on the measurement protocol, we distinguish three fundamental scenarios (a) enriched quantum criticality, characterized by a logarithmic entanglement growth with a floating prefactor, or the loss of criticality, indicated by an entanglement growth with either (b) an area-law or (c) a volume-law. For each scenario, we discuss the impact of imperfect measurements, which reduce the purity of the wavefunction and are equivalent to Markovian decoherence, and present a set of observables, e.g., real-space correlations, the relaxation time, and the entanglement structure, to classify the measurement-induced dynamics for both pure and mixed states. Finally, we present an experimental tomography scheme, which grants access to the density operator of the system by using the continuous measurement record only.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Minoguchi, Y. UNSPECIFIED UNSPECIFIED UNSPECIFIED Rabl, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Buchhold, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-667811
DOI:	10.21468/SciPostPhys.12.1.009
Journal or Publication Title:	SciPost Phys.
Volume:	12
Number:	1
Date:	2022
Publisher:	SCIPOST FOUNDATION
Place of Publication:	AMSTERDAM
ISSN:	2542-4653
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ERROR-CORRECTING CODES; BOUND ENTANGLEMENT; CONFORMAL SYMMETRY; QUANTUM; PHYSICS; CHAOS Multiple languages Physics, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/66781