CliffordOperator constructor from PauliOperator

CHANGELOG.md

@@ -7,6 +7,8 @@
 
 ## v0.10.1-dev
 
+- Add a `CliffordOperator` constructor that builds a dense clifford from a `PauliOperator`
+- Add a `phases` getter for `CliffordOperator`
 - The generalized hypergraph product code is implemented in the ECC submodule.
 - Add novel `[[n² + m²,(n - rank([C ∣ M]))² + (m − rank([C ∣ M]ᵀ))², d]]` quantum Tillich-Zémor `random_TillichZemor_code` codes to `QECCore` and introduce `QECCoreNemoExt` for accurate matrix `rank` computation.
 - The D-dimensional Surface and Toric codes are now implemented using `Oscar`'s chain complexes and `GF2` homology in the ECC submodule.

src/dense_cliffords.jl

@@ -63,6 +63,12 @@ end
 CliffordOperator(op::CliffordOperator) = op
 CliffordOperator(paulis::AbstractVector{<:PauliOperator}) = CliffordOperator(Tableau(paulis))
 CliffordOperator(destab::Destabilizer) = CliffordOperator(tab(destab))
+function CliffordOperator(pauli::PauliOperator)
+    res = one(CliffordOperator, nqubits(pauli))
+    comm!(phases(res), pauli, tab(res))
+    tab(res).phases .*= 0x02
+    return res
+end
 
 Base.:(==)(l::CliffordOperator, r::CliffordOperator) = tab(l) == tab(r)
 Base.hash(c::T, h::UInt) where {T<:CliffordOperator} = hash(T, hash(tab(c), h))
@@ -91,6 +97,7 @@ function Base.copy(c::CliffordOperator)
 end
 
 @inline nqubits(c::CliffordOperator) = nqubits(tab(c))
+@inline phases(c::CliffordOperator) = phases(tab(c))
 
 Base.zero(c::CliffordOperator) = CliffordOperator(zero(tab(c)))
 Base.zero(::Type{<:CliffordOperator}, n) = CliffordOperator(zero(Tableau, 2n, n))

test/test_cliff.jl

@@ -23,6 +23,13 @@
         @testset "Constructors" begin
             @test_throws DimensionMismatch CliffordOperator(T"X")
         end
+        @testset "Constructor from PauliOperator" begin
+            for n in test_sizes
+                l = random_clifford(n)
+                pauli = random_pauli(n)
+                @test apply!(copy(l), pauli; phases=true) == apply!(l, CliffordOperator(pauli); phases=true)
+            end
+        end
         @testset "Permutations of qubits" begin
             for c in [tCNOT, tId1⊗tHadamard, tCNOT⊗tCNOT, tensor_pow(tCNOT,6), tensor_pow(tCNOT,7), tensor_pow(tCNOT,6)⊗tPhase, tensor_pow(tCNOT,7)⊗tPhase]
                 for rep in 1:5