Noninvasive measurement of dynamic correlation functions
Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
American Physical Society
Abstract
The measurement of dynamic correlation functions of quantum systems is complicated by measurement
backaction. To facilitate such measurements we introduce a protocol, based on weak ancilla-system couplings,
that is applicable to arbitrary (pseudo)spin systems and arbitrary equilibrium or nonequilibrium initial states.
Different choices of the coupling operator give access to the real and imaginary parts of the dynamic correlation
function. This protocol reduces disturbances due to the early-time measurements to a minimum, and we quantify
the deviation of the measured correlation functions from the theoretical, unitarily evolved ones. Implementations
of the protocol in trapped ions and other experimental platforms are discussed. For spin-1/2 models and single-site
observables we prove that measurement backaction can be avoided altogether, allowing for the use of ancilla-free
protocols.
Description
CITATION: Uhrich, P., et al. 2017. Noninvasive measurement of dynamic correlation functions. Physical Review A, 96(2):022127, doi:10.1103/PhysRevA.96.022127.
The original publication is available at http://journals.aps.org/pra
The original publication is available at http://journals.aps.org/pra
Keywords
Measurement, Quantum systems, Correlation functions, Hamiltonian mechanics
Citation
Uhrich, P., et al. 2017. Noninvasive measurement of dynamic correlation functions. Physical Review A, 96(2):022127, doi:10.1103/PhysRevA.96.022127