fixes #77

iitis · Sep 3, 2019 · 2cf8521 · 2cf8521
1 parent 54a8e75
commit 2cf8521
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diff --git a/src/channels/compositions.jl b/src/channels/compositions.jl
@@ -86,6 +86,20 @@ function compose(::Type{T}, Φ1::T1, Φ2::T2) where {T<:AbstractQuantumOperation
     convert(T, so)
 end
 
+function compose(Φ1::UnitaryChannel{M1}, Φ2::UnitaryChannel{M2}) where {M1<:AbstractMatrix{<:Number}, M2<:AbstractMatrix{<:Number}}
+    M = promote_type(M1, M2)
+    compose(UnitaryChannel{M}, Φ1, Φ2)
+end
+
+function compose(::Type{UnitaryChannel{M}}, Φ1::UnitaryChannel{M1}, Φ2::UnitaryChannel{M2}) where {M<:AbstractMatrix{<:Number}, M1<:AbstractMatrix{<:Number}, M2<:AbstractMatrix{<:Number}}
+    Φ1.odim == Φ2.idim ? () : throw(ArgumentError("Unitaries are incompatible"))
+
+    um1 = Φ1.matrix
+    um2 = Φ2.matrix
+    um = um2 * um1
+    UnitaryChannel{M}(convert(M, um), Φ1.idim, Φ2.odim)
+end
+
 function compose(Φ1::T, Φ2::T) where {T<:AbstractQuantumOperation{<:Number}}
     compose(T, Φ1, Φ2)
 end

diff --git a/test/channels.jl b/test/channels.jl
@@ -136,6 +136,13 @@ end
 
     c = UnitaryChannel(Diagonal(ComplexF64[1 -1.0im]))
     @test c isa UnitaryChannel{<:Diagonal}
+
+    u1 = UnitaryChannel([cos(1) sin(1); -sin(1) cos(1)])
+    u2 = UnitaryChannel([cos(2) sin(2); -sin(2) cos(2)])
+    @test compose(u1, u2).matrix ≈ u2.matrix * u1.matrix
+    @test compose(UnitaryChannel{Array{Float64,2}}, u1, u2).matrix ≈ u2.matrix * u1.matrix
+
+    @test kron(u1, u2).matrix ≈ kron(u1.matrix, u2.matrix)
 end
 
 @testset "POVMMeasurement" begin