num_expect=0 although evolution can run

[ferrispnugraha]

Bug Description

Run a simple evolution, not recording the expectation value

Code to Reproduce the Bug

using QuantumToolbox

H = 2 * π * 0.1 * sigmax()
ψ0 = basis(2, 0) # spin-up
tlist = LinRange(0.0, 10.0, 20)

prob = sesolveProblem(H, ψ0, tlist, e_ops = [sigmaz()])
sol = sesolve(prob)

Code Output

Progress: [==============================] 100.0% --- Elapsed Time: 0h 00m 02s (ETA: 0h 00m 00s)

Solution of time evolution
(return code: Success)
--------------------------
num_states = 1
num_expect = 0
ODE alg.: OrdinaryDiffEqTsit5.Tsit5{typeof(OrdinaryDiffEqCore.trivial_limiter!), typeof(OrdinaryDiffEqCore.trivial_limiter!), Static.False}(OrdinaryDiffEqCore.trivial_limiter!, OrdinaryDiffEqCore.trivial_limiter!, static(false))
abstol = 1.0e-8
reltol = 1.0e-6

Expected Behaviour

As in https://qutip.org/QuantumToolbox.jl/stable/users_guide/time_evolution/sesolve

Solution of time evolution
(return code: Success)

num_states = 1
num_expect = 1
ODE alg.: OrdinaryDiffEqTsit5.Tsit5{typeof(OrdinaryDiffEqCore.trivial_limiter!), typeof(OrdinaryDiffEqCore.trivial_limiter!), Static.False}(OrdinaryDiffEqCore.trivial_limiter!, OrdinaryDiffEqCore.trivial_limiter!, static(false))
abstol = 1.0e-8
reltol = 1.0e-6

Your Environment

QuantumToolbox.jl: Quantum Toolbox in Julia
≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡
Copyright © QuTiP team 2022 and later.
Current admin team:
    Alberto Mercurio and Yi-Te Huang

Package information:
====================================
Julia              Ver. 1.11.1
QuantumToolbox     Ver. 0.22.0
SciMLOperators     Ver. 0.3.12
LinearSolve        Ver. 2.38.0
OrdinaryDiffEqCore Ver. 1.13.0

System information:
====================================
OS       : Windows (x86_64-w64-mingw32)
CPU      : 20 × 12th Gen Intel(R) Core(TM) i7-12700H
Memory   : 31.679 GB
WORD_SIZE: 64
LIBM     : libopenlibm
LLVM     : libLLVM-16.0.6 (ORCJIT, alderlake)
BLAS     : libopenblas64_.dll (ilp64)
Threads  : 1 (on 20 virtual cores)

Additional Context

expt_z = real(sol.expect[1,:]) 
expt_y = real(sol.expect[2,:])

returns the following error (expect is empty):

MethodError: no method matching getindex(::Nothing, ::Int64, ::Colon)
The function `getindex` exists, but no method is defined for this combination of argument types.

[albertomercurio]

Very strange, the code works for me.

julia> sol = sesolve(prob)
Progress: [==============================] 100.0% --- Elapsed Time: 0h 00m 04s (ETA: 0h 00m 00s)
Solution of time evolution
(return code: Success)
--------------------------
num_states = 1
num_expect = 1
ODE alg.: OrdinaryDiffEqTsit5.Tsit5{typeof(OrdinaryDiffEqCore.trivial_limiter!), typeof(OrdinaryDiffEqCore.trivial_limiter!), Static.False}(OrdinaryDiffEqCore.trivial_limiter!, OrdinaryDiffEqCore.trivial_limiter!, static(false))
abstol = 1.0e-8
reltol = 1.0e-6

julia> QuantumToolbox.versioninfo()

 QuantumToolbox.jl: Quantum Toolbox in Julia
≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡
Copyright © QuTiP team 2022 and later.
Current admin team:
    Alberto Mercurio and Yi-Te Huang

Package information:
====================================
Julia              Ver. 1.11.2
QuantumToolbox     Ver. 0.23.0
SciMLOperators     Ver. 0.3.11
LinearSolve        Ver. 2.38.0
OrdinaryDiffEqCore Ver. 1.13.0

System information:
====================================
OS       : Linux (x86_64-linux-gnu)
CPU      : 32 × 13th Gen Intel(R) Core(TM) i9-13900KF
Memory   : 62.514 GB
WORD_SIZE: 64
LIBM     : libopenlibm
LLVM     : libLLVM-16.0.6 (ORCJIT, alderlake)
BLAS     : libopenblas64_.so (ilp64)
Threads  : 16 (on 32 virtual cores)

I see that you are using Windows. Maybe it's related to that. But I doubt because we should have runtests also for windows machines.

[ytdHuang]

@ferrispnugraha

Thank you for reporting this bug.

There is an incompatibility issue between QuantumToolbox>=0.22.0 and DiffEqCallbacks.jl<4.2.1

Solution 1

This issue can be solved quickly by updating DiffEqCallbacks.jl>=4.2.1 in your local Julia environment:

just open Julia, change to package mode by ], and then

pkg> update DiffEqCallbacks

or

using Pkg; Pkg.update("DiffEqCallbacks")

Solution 2

We will also update the [compat] of DiffEqCallbacks.jl in the next patch release (v0.23.1).

So you can also solve this problem by updating QuantumToolbox.jl to v0.23.1 (but this needs to wait PR #335 to be merged)