add a sugar for density matrix, cheers

QuantumBFS · Jul 4, 2018 · ce2b421 · ce2b421
1 parent d14d244
commit ce2b421
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diff --git a/src/Registers/DensityMatrix.jl b/src/Registers/DensityMatrix.jl
@@ -5,6 +5,20 @@ end
 DensityMatrix(state::MT) where {T, MT<:AbstractArray{T, 3}} = DensityMatrix{size(state, 3), T, MT}(state)
 DensityMatrix(state::MT) where {T, MT<:AbstractArray{T, 2}} = (state=state[:,:,1:1]; DensityMatrix{1, T, typeof(state)}(state))
 
+"""
+    density_matrix(register)
+
+Returns the density matrix of this register.
+"""
+function density_matrix end
+
+"""
+    ρ(register)
+
+Returns the density matrix of this register.
+"""
+const ρ = density_matrix
+
 density_matrix(reg::DefaultRegister{1}) = DensityMatrix(reg.state*reg.state')
 
 function density_matrix(reg::DefaultRegister{B}) where B

diff --git a/src/Registers/Registers.jl b/src/Registers/Registers.jl
@@ -24,7 +24,7 @@ export register, zero_state, rand_state, randn_state, stack, uniform_state
 
 # bit_str
 export @bit_str, asindex
-export DensityMatrix, density_matrix
+export DensityMatrix, density_matrix, ρ
 export fidelity, tracedist