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Merged
merged 10 commits into from
Sep 27, 2024
Merged

Type promotion between MixedDestabilizer, Stabilizer and others, also used in ⊗ #354

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7da1f9c
Bug fix to StackOverflowError for md ⊗ SX where typeof(md) is MixedDe…
Fe-r-oz Sep 7, 2024
bbb12df
Merge branch 'QuantumSavory:master' into i339
Fe-r-oz Sep 14, 2024
0435a8b
add code review suggestions
Fe-r-oz Sep 14, 2024
a06f66e
improve code formatting
Fe-r-oz Sep 14, 2024
be8ce6f
minor formatting
Fe-r-oz Sep 14, 2024
066d7c2
further polish
Fe-r-oz Sep 15, 2024
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remove nonsense code
Fe-r-oz Sep 15, 2024
cc5b84d
add code review suggestions: cut down on power_rules, simplify conver…
Fe-r-oz Sep 16, 2024
11376fd
revamp promote rules
Fe-r-oz Sep 17, 2024
99ab972
remove redundant comments and add back an incorrectly removed TODO
Krastanov Sep 27, 2024
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22 changes: 22 additions & 0 deletions src/QuantumClifford.jl
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Expand Up @@ -989,6 +989,28 @@ function _apply!(stab::AbstractStabilizer, p::PauliOperator, indices; phases::Va
stab
end

##############################
# Conversion and promotion
##############################

Base.promote_rule(::Type{<:MixedStabilizer{T}} , ::Type{<:Stabilizer{T}} ) where {T<:Tableau} = Stabilizer{T}
Base.promote_rule(::Type{<:MixedStabilizer{T}} , ::Type{<:MixedStabilizer{T}}) where {T<:Tableau} = Stabilizer{T}
Base.promote_rule(::Type{<:MixedStabilizer{T}} , ::Type{<:Destabilizer{T}} ) where {T<:Tableau} = MixedDestabilizer{T}
Base.promote_rule(::Type{<:Stabilizer{T}} , ::Type{<:Destabilizer{T}} ) where {T<:Tableau} = MixedDestabilizer{T}
Base.promote_rule(::Type{<:Destabilizer{T}} , ::Type{<:Destabilizer{T}} ) where {T<:Tableau} = MixedDestabilizer{T}
Base.promote_rule(::Type{<:MixedDestabilizer{T}}, ::Type{<:Stabilizer{T}} ) where {T<:Tableau} = MixedDestabilizer{T}
Base.promote_rule(::Type{<:MixedDestabilizer{T}}, ::Type{<:Destabilizer{T}} ) where {T<:Tableau} = MixedDestabilizer{T}
Base.promote_rule(::Type{<:MixedDestabilizer{T}}, ::Type{<:MixedStabilizer{T}}) where {T<:Tableau} = MixedDestabilizer{T}
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I do not agree with many of these rules. A MixedStabilizer can not be converted to Stabilizer.

From special to general the conversions would be (missing a lot of type parameterizations):

Stabilizer, T<:Union{MixedStabilizer, Destabilizer, MixedDestabilizer} -> T
Destabilizer, MixedDestabilizer -> MixedDestabilizer
MixedStabilizer, MixedDestabilizer -> MixedDestabilizer

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Thank you, I agree with you. I will remove the nonsensical rules. Also, incorporate your last comment about not missing the type parameterizations.

tensor(MixedStab(...), S"X") causes stack overflow error if a user wants to cause it, so most of the nonsensical rules were to avoid the stack overflow errors. But yeah, they result in nonsense objects which I completely overlooked. Sorry about that.

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Thank you very much for special to general conversions #354 (comment), I have added them as instructed.


Base.convert(::Type{<:Stabilizer{T}} , x::MixedStabilizer{T} ) where {T<:Tableau} = Stabilizer(tab(x))
Base.convert(::Type{<:MixedStabilizer{T}} , x::MixedStabilizer{T} ) where {T<:Tableau} = Stabilizer(tab(x))
Base.convert(::Type{<:Stabilizer{T}} , x::Destabilizer{T} ) where {T<:Tableau} = MixedDestabilizer(x)
Base.convert(::Type{<:Destabilizer{T}} , x::Destabilizer{T} ) where {T<:Tableau} = MixedDestabilizer(x)
Base.convert(::Type{<:MixedDestabilizer{T}} , x::Stabilizer{T} ) where {T<:Tableau} = MixedDestabilizer(x)
Base.convert(::Type{<:MixedDestabilizer{T}} , x::Destabilizer{T} ) where {T<:Tableau} = MixedDestabilizer(x)
Base.convert(::Type{<:Destabilizer{T}} , x::MixedStabilizer{T} ) where {T<:Tableau} = MixedDestabilizer(Stabilizer(tab(x)))
Base.convert(::Type{<:MixedDestabilizer{T}} , x::MixedStabilizer{T} ) where {T<:Tableau} = MixedDestabilizer(Stabilizer(tab(x)))
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All of these converts can be implemented as something much simpler, e.g. convert(::T, x::AbstractStabilizer) where {T<:Type{S}, S<:AbstractStabilizer} = S(x) because we already have the constructors implemented. I probable screwed up some of the type syntax or names of types, but this is the rough idea.


##############################
# Helpers for binary codes
##############################
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117 changes: 115 additions & 2 deletions src/linalg.jl
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Expand Up @@ -158,11 +158,124 @@ julia> tensor(s, s)
- ____Z_
```

Tensor product between [`MixedDestabilizer`](@ref) and [`Stabilizer`](@ref):

```jldoctest promote
julia> md = MixedDestabilizer(T"Z//X", 1)
𝒟ℯ𝓈𝓉𝒶𝒷
+ Z
𝒮𝓉𝒶𝒷
+ X

julia> tensor(S"X", md)
𝒟ℯ𝓈𝓉𝒶𝒷
+ Z_
+ _Z
𝒮𝓉𝒶𝒷
+ X_
+ _X
```

Tensor product between [`MixedDestabilizer`](@ref) and [`Destabilizer`](@ref):

```jldoctest promote
julia> d = Destabilizer(T"-Y//-X")
𝒟ℯ𝓈𝓉𝒶𝒷
- Y
𝒮𝓉𝒶𝒷
- X

julia> tensor(d, md)
𝒟ℯ𝓈𝓉𝒶𝒷
- Y_
+ _Z
𝒮𝓉𝒶𝒷
- X_
+ _X
```

Tensor product between [`MixedStabilizer`](@ref) and [`Stabilizer`](@ref):

```jldoctest promote
julia> ms = MixedStabilizer(S"-XZ//-ZX")
- XZ
- ZX

julia> tensor(S"X", ms)
+ X__
- _XZ
- _ZX
```

Tensor product between [`Stabilizer`](@ref) and [`Destabilizer`](@ref):

```jldoctest promote
julia> tensor(S"X", d)
𝒟ℯ𝓈𝓉𝒶𝒷
+ Z_
- _Y
𝒮𝓉𝒶𝒷
+ X_
- _X
```

Tensor product between [`MixedStabilizer`](@ref) and [`MixedDestabilizer`](@ref):

```jldoctest promote
julia> tensor(md, ms)
𝒟ℯ𝓈𝓉𝒶𝒷
+ Z__
+ _Z_
+ __Z
𝒮𝓉𝒶𝒷━
+ X__
- _XZ
- _ZX
```

Tensor product between [`MixedStabilizer`](@ref) and [`Destabilizer`](@ref):

```jldoctest promote
julia> tensor(d, ms)
𝒟ℯ𝓈𝓉𝒶𝒷
- Y__
+ _Z_
+ __Z
𝒮𝓉𝒶𝒷━
- X__
- _XZ
- _ZX
```

Tensor product between [`Destabilizer`](@ref) and [`Destabilizer`](@ref):

```jldoctest promote
julia> tensor(d, d)
𝒟ℯ𝓈𝓉𝒶𝒷
- Y_
- _Y
𝒮𝓉𝒶𝒷
- X_
- _X
```

Tensor product between [`MixedStabilizer`](@ref) and [`MixedStabilizer`](@ref):

```jldoctest promote
julia> tensor(ms, ms)
- XZ__
- ZX__
- __XZ
- __ZX
```

See also [`tensor_pow`](@ref)."""
function tensor end

function tensor(ops::AbstractStabilizer...) # TODO optimize this by doing conversion to common type to enable preallocation
foldl(⊗, ops[2:end], init=ops[1])
function tensor(ops::AbstractStabilizer...)
ct = promote_type(map(typeof, ops)...)
conv_ops = map(x -> convert(ct, x), ops)
return foldl(⊗, conv_ops)
end

"""Repeated tensor product of an operators or a tableau.
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22 changes: 22 additions & 0 deletions test/test_stabs.jl
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Expand Up @@ -55,6 +55,28 @@
stabs = [s[1:i] for s in [random_stabilizer(n) for n in [32,16,16,64,63,65,129,128,127]] for i in rand(1:10)];
mdstabs = MixedDestabilizer.(stabs);
@test canonicalize!(⊗(stabs...)) == canonicalize!(stabilizerview(⊗(mdstabs...)))
md = MixedDestabilizer(random_destabilizer(n))
s = random_stabilizer(n)
mds = md⊗s
@test mixed_destab_looks_good(mds)
estab = stabilizerview(md)⊗s
@test canonicalize!(copy(stabilizerview(mds))) == canonicalize!(estab)
d = random_destabilizer(n)
dmd = d⊗md
@test mixed_destab_looks_good(dmd)
ms = MixedStabilizer(random_stabilizer(n))
mss = s⊗ms
@test mixed_stab_looks_good(mss)
sd = random_stabilizer(n)⊗random_destabilizer(n)
@test mixed_destab_looks_good(sd)
mdms = md⊗ms
@test mixed_destab_looks_good(mdms)
dms = d⊗ms
@test mixed_destab_looks_good(dms)
dd = d⊗d
@test destab_looks_good(dd)
msms = ms⊗ms
@test mixed_stab_looks_good(msms)
end
end

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