TY - JOUR
AU - Michael Perlin
AU - Ana Maria Rey
AB - We present an efficient method to compute short-time expectation values in large collective spin systems with typical forms of Markovian decoherence. Our method is based on a Taylor expansion of a formal solution to the equations of motion for Heisenberg operators. This expansion can be truncated at finite order to obtain virtually exact results at short times that are relevant for metrological applications such as spin squeezing. In order to evaluate the expansion for Heisenberg operators, we compute the relevant structure constants of a collective spin operator algebra. We demonstrate the utility of our method by computing spin squeezing, two-time correlation functions, and out-of-time-ordered correlators for 10<sup>4</sup> spins in strong-decoherence regimes that are otherwise inaccessible via existing numerical methods. Our method can be straightforwardly generalized to the case of a collective spin coupled to bosonic modes, relevant for trapped ion and cavity QED experiments, and may be used to investigate short-time signatures of quantum chaos and information scrambling.
BT - Physical Review A
DA - 2020-02
DO - 10.1103/PhysRevA.101.023601
N2 - We present an efficient method to compute short-time expectation values in large collective spin systems with typical forms of Markovian decoherence. Our method is based on a Taylor expansion of a formal solution to the equations of motion for Heisenberg operators. This expansion can be truncated at finite order to obtain virtually exact results at short times that are relevant for metrological applications such as spin squeezing. In order to evaluate the expansion for Heisenberg operators, we compute the relevant structure constants of a collective spin operator algebra. We demonstrate the utility of our method by computing spin squeezing, two-time correlation functions, and out-of-time-ordered correlators for 10<sup>4</sup> spins in strong-decoherence regimes that are otherwise inaccessible via existing numerical methods. Our method can be straightforwardly generalized to the case of a collective spin coupled to bosonic modes, relevant for trapped ion and cavity QED experiments, and may be used to investigate short-time signatures of quantum chaos and information scrambling.
PB - American Physical Society
PY - 2020
EP - 023601
T2 - Physical Review A
TI - Short-time expansion of Heisenberg operators in open collective quantum spin systems
UR - https://link.aps.org/doi/10.1103/PhysRevA.101.023601
VL - 101
ER -