# Calculation of two-time correlation function and spectrum in quantumoptics.jl

**URL:** <https://discourse.julialang.org/t/calculation-of-two-time-correlation-function-and-spectrum-in-quantumoptics-jl/97009>\
**Category:** Specific Domains\
**Tags:** package, quantum\
**Created:** [April 3, 2023, 10:52am UTC](https://discourse.julialang.org/t/calculation-of-two-time-correlation-function-and-spectrum-in-quantumoptics-jl/97009 "2023-04-03T10:52:26Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![arpan\_chatterjee](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/arpan_chatterjee/32/47433_2.png) [@arpan\_chatterjee](https://discourse.julialang.org/u/arpan_chatterjee)\
**Post date:** [April 3, 2023, 10:52am UTC](https://discourse.julialang.org/t/calculation-of-two-time-correlation-function-and-spectrum-in-quantumoptics-jl/97009/1 "2023-04-03T10:52:26Z")

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If I have some time-dependent Hamiltonian whose frequency is time dependent not amplitude as described in the example of the documentation in quantumoptics.jl. Then How can I construct two-time correlation function for such time-dependent evolution. Also How to get the spectrum from there. Clearly  
such cases do not directly pose any steady-state if evolved with a master equation.