Uhrich, PCastrignano, SUys, HermannKastner, M2017-09-292017-09-292017-08Uhrich, P., Castrignano, S., Uys, H. et al. 2017. Noninvasive measurement of dynamic correlation functions. Physical Review A, vol. 96: DOI: 10.1103/PhysRevA.96.0221271050-2947DOI: 10.1103/PhysRevA.96.022127https://journals.aps.org/pra/abstract/10.1103/PhysRevA.96.022127http://hdl.handle.net/10204/9612Physical Review A, vol. 96: DOI: 10.1103/PhysRevA.96.022127The 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.enNoninvasive measurementsCorrelation functionQuantum simulationArticleUhrich, P., Castrignano, S., Uys, H., & Kastner, M. (2017). Noninvasive measurement of dynamic correlation functions. http://hdl.handle.net/10204/9612Uhrich, P, S Castrignano, Hermann Uys, and M Kastner "Noninvasive measurement of dynamic correlation functions." (2017) http://hdl.handle.net/10204/9612Uhrich P, Castrignano S, Uys H, Kastner M. Noninvasive measurement of dynamic correlation functions. 2017; http://hdl.handle.net/10204/9612.TY - Article AU - Uhrich, P AU - Castrignano, S AU - Uys, Hermann AU - Kastner, M AB - 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. DA - 2017-08 DB - ResearchSpace DP - CSIR KW - Noninvasive measurements KW - Correlation function KW - Quantum simulation LK - https://researchspace.csir.co.za PY - 2017 SM - 1050-2947 T1 - Noninvasive measurement of dynamic correlation functions TI - Noninvasive measurement of dynamic correlation functions UR - http://hdl.handle.net/10204/9612 ER -