test_nonclifford.jl

@testitem "NonClifford" begin
    using QuantumClifford: StabMixture, rowdecompose, PauliChannel, mul_left!, mul_right!
    using InteractiveUtils
    using Random

    @testset "Pauli decomposition into destabilizers" begin
        for n in [1,2,63,64,65,66,300]
            p = random_pauli(n; nophase=true)
            s = random_destabilizer(n)
            phase, b, c = rowdecompose(p,s)
            p0 = zero(p)
            for (i,f) in pairs(b)
                f && mul_right!(p0, destabilizerview(s), i)
            end
            for (i,f) in pairs(c)
                f && mul_right!(p0, stabilizerview(s), i)
            end
            @test (im)^phase*p0 == p
        end
    end

    ##

    @testset "PauliChannel T gate ^4 = Id" begin
        tgate = pcT
        state = StabMixture(S"X")

        apply!(state, tgate)
        apply!(state, tgate)
        apply!(state, tgate)
        apply!(state, tgate)

        @test isapprox(state.destabweights |> values |> collect, [1])
        @test state.destabweights |> keys |> collect == [([1],[1])]
    end

    ##

    @test_throws ArgumentError StabMixture(S"XX")
    @test_throws ArgumentError PauliChannel(((P"X", P"Z"), (P"X", P"ZZ")), (1,2))
    @test_throws ArgumentError PauliChannel(((P"X", P"Z"), (P"X", P"Z")), (1,))
    @test_throws ArgumentError UnitaryPauliChannel((P"X", P"ZZ"), (1,2))
    @test_throws ArgumentError UnitaryPauliChannel((P"X", P"Z"), (1,))
end