Continuous Gaussian Measurements of the Free Boson CFT: A model for
Exactly Solvable and Detectable Measurement-Induced Dynamics
- URL: http://arxiv.org/abs/2108.04256v2
- Date: Wed, 27 Oct 2021 18:00:01 GMT
- Title: Continuous Gaussian Measurements of the Free Boson CFT: A model for
Exactly Solvable and Detectable Measurement-Induced Dynamics
- Authors: Y. Minoguchi, P. Rabl, M. Buchhold
- Abstract summary: We introduce a scenario of measurement-induced many body evolution, which possesses an exact analytical solution: bosonic measurements.
We consider an elementary model for quantum criticality, the free boson conformal field theory, and investigate in which way criticality is modified under measurements.
For each scenario, we discuss the impact of imperfect measurements, which reduce the purity of the wavefunction and are equivalent to Markovian decoherence.
- Score: 0.0
- License: http://creativecommons.org/licenses/by/4.0/
- 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.
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