diff --git a/src/general_functions.jl b/src/general_functions.jl
index 1f418bfa..6a02ed2c 100644
--- a/src/general_functions.jl
+++ b/src/general_functions.jl
@@ -110,6 +110,12 @@ function vec2mat(A::AbstractVector)
     reshape(A, newsize, newsize)
 end
 
+@doc raw"""
+    vec2mat(A::QuantumObject)
+
+Convert a quantum object from vector (`OperatorKetQuantumObject`-type) to matrix (`OperatorQuantumObject`-type)
+"""
+vec2mat(A::QuantumObject{<:AbstractArray{T},OperatorKetQuantumObject}) where {T} = QuantumObject(vec2mat(A.data), OperatorQuantumObject, A.dims)
 
 @doc raw"""
     gaussian(x::Number, μ::Number, σ::Number)
@@ -387,4 +393,11 @@ function mat2vec(::Type{M}) where M <: Union{Adjoint{<:BlasFloat,<:SparseMatrixC
     npar = length(par)
     (2 == npar) || error("Type $M is not supported.")
     return SparseVector{par[1], par[2]}
-end
\ No newline at end of file
+end
+
+@doc raw"""
+    mat2vec(A::QuantumObject)
+
+Convert a quantum object from matrix (`OperatorQuantumObject`-type) to vector (`OperatorKetQuantumObject`-type)
+"""
+mat2vec(A::QuantumObject{<:AbstractArray{T},OperatorQuantumObject}) where {T} = QuantumObject(mat2vec(A.data), OperatorKetQuantumObject, A.dims)
\ No newline at end of file
diff --git a/test/quantum_objects.jl b/test/quantum_objects.jl
index 0f01baac..2c9ce581 100644
--- a/test/quantum_objects.jl
+++ b/test/quantum_objects.jl
@@ -59,11 +59,11 @@
     # Operator-Ket, Operator-Bra tests
     H  = 0.3 * sigmax() + 0.7 * sigmaz()
     L  = liouvillian(H)
-    a4 = rand(ComplexF64, 2, 2)
-    ρ  = Qobj(a4)
-    ρ_ket = Qobj(mat2vec(a4), type=OperatorKetQuantumObject)
+    ρ  = Qobj(rand(ComplexF64, 2, 2))
+    ρ_ket = mat2vec(ρ)
     ρ_bra = ρ_ket'
-    @test ρ_bra == Qobj(mat2vec(a4)', type=OperatorBraQuantumObject)
+    @test ρ_bra == Qobj(mat2vec(ρ.data)', type=OperatorBraQuantumObject)
+    @test ρ == vec2mat(ρ_ket)
     @test isket(ρ_ket) == false
     @test isbra(ρ_ket) == false
     @test isoper(ρ_ket) == false