project*rand! for Register

CHANGELOG.md

@@ -1,6 +1,10 @@
 # News
 
-## v0.5.8
+## v0.5.9 - 2022-08-17
+
+- `Register` now works with `traceout!` and `project*rand!`.
+
+## v0.5.8 - 2022-08-15
 
 - Implement `projectremoverand!` which besides performing a projective measurement like `projectrand!` also removes the measured qubit from the tableau, returning a smaller tableau. Not yet exported in public API.
 

Project.toml

@@ -1,7 +1,7 @@
 name = "QuantumClifford"
 uuid = "0525e862-1e90-11e9-3e4d-1b39d7109de1"
 authors = ["Stefan Krastanov <stefan@krastanov.org>"]
-version = "0.5.8"
+version = "0.5.9"
 
 [deps]
 Combinatorics = "861a8166-3701-5b0c-9a16-15d98fcdc6aa"

src/classical_register.jl

@@ -54,8 +54,29 @@ function apply!(r::Register, m::PauliMeasurement{A,B,T}) where {A,B,T}
     T==Int && (bitview(r)[m.storagebit] = iszero(res))
     r
 end
+function projectXrand!(r::Register, m)
+    q = quantumstate(r)
+    _, res = projectXrand!(q,m)
+    r, res
+end
+function projectYrand!(r::Register, m)
+    q = quantumstate(r)
+    _, res = projectYrand!(q,m)
+    r, res
+end
+function projectZrand!(r::Register, m)
+    q = quantumstate(r)
+    _, res = projectZrand!(q,m)
+    r, res
+end
 function projectrand!(r::Register, m)
     q = quantumstate(r)
     _, res = projectrand!(q,m)
     r, res
 end
+
+function traceout!(r::Register, arg)
+    q = quantumstate(r)
+    traceout!(q,arg)
+    q
+end

test/runtests.jl

@@ -41,6 +41,7 @@ doset("cliffords")          && include("./test_cliff.jl")
 doset("symbolic cliffords") && include("./test_symcliff.jl")
 doset("random")             && include("./test_random.jl")
 doset("noisy circuits")     && include("./test_noisycircuits.jl")
+doset("syndrome measure")   && include("./test_syndromemeas.jl")
 doset("bitpack")            && include("./test_bitpack.jl")
 doset("graphs")             && include("./test_graphs.jl")
 doset("hash")               && include("./test_hash.jl")

test/test_syndromemeas.jl

@@ -0,0 +1,57 @@
+using QuantumClifford.Experimental.NoisyCircuits
+
+function test_syndromemeas()
+    @testset "Syndrome Measurements" begin
+        codeˢᵗᵉᵃⁿᵉ = S"Z__Z_ZZ
+                       _Z_ZZ_Z
+                       __Z_ZZZ
+                       X__X_XX
+                       _X_XX_X
+                       __X_XXX";
+        function get_check(code,index) # TODO a fairly ugly piece of code that should just be part of the library
+            s,n = size(code)
+            @assert index<=s
+            op = code[index]
+            anc = n+1
+            circuit = AbstractOperation[]
+            measurement = nothing
+            resetgate = nothing
+            for qubit in 1:n
+                if op[qubit] == (false, true) # it is a Z
+                    if isnothing(measurement) || measurement==sMZ
+                        resetgate = Reset(S"-Z",[anc])
+                        measurement = sMZ
+                    else
+                        error("can not do mixed syndromes")
+                    end
+                    push!(circuit, sCNOT(qubit, anc))
+                elseif op[qubit] == (true, false) # it is a X
+                    if isnothing(measurement) || measurement==sMX
+                        resetgate = Reset(S"-X",[anc])
+                        measurement = sMX
+                    else
+                        error("can not do mixed syndromes")
+                    end
+                    push!(circuit, sCNOT(anc, qubit))
+                elseif op[qubit] == (true, true) # it is a Y
+                    error("can not do Y syndromes")
+                end
+            end
+            push!(circuit,measurement(anc,index))
+            circuit = AbstractOperation[resetgate,circuit...]
+        end
+        function get_all_checks(code)
+            s,n = size(code)
+            vcat([get_check(code,i) for i in 1:s]...)
+        end
+        # test the code is correct
+        state = Register(MixedDestabilizer(codeˢᵗᵉᵃⁿᵉ ⊗ S"Z"),zeros(Bool,6))
+        full_circuit = get_all_checks(codeˢᵗᵉᵃⁿᵉ)
+        for _ in 1:100
+            err = random_pauli(7;realphase=true)
+            @test mctrajectory!(apply!(copy(state),(err ⊗ P"I")),full_circuit)[1].bits == comm(err*codeˢᵗᵉᵃⁿᵉ, err)
+        end
+    end
+end
+
+test_syndromemeas()