adding all missing types of two qubit SWAP gates and sSQRTZZ/sInvSQRTZZ gate (#336)

---------

Co-authored-by: Stefan Krastanov <[email protected]>
Co-authored-by: Stefan Krastanov <[email protected]>

Author: Fe-r-oz

CHANGELOG.md

@@ -5,6 +5,11 @@
 
 # News
 
+## v0.9.13 - dev
+
+- Implementing additional named two-qubit gates: `sSWAPCX, sInvSWAPCX, sCZSWAP, sCXSWAP, sISWAP, sInvISWAP,
+    sSQRTZZ, sInvSQRTZZ`
+
 ## v0.9.12 - 2024-10-18
 
 - Minor compat fixes for julia 1.11 in the handling of `hgp`

src/QuantumClifford.jl

@@ -51,7 +51,8 @@ export
     sHadamardXY, sHadamardYZ, sSQRTX, sInvSQRTX, sSQRTY, sInvSQRTY, sCXYZ, sCZYX,
     sCNOT, sCPHASE, sSWAP,
     sXCX, sXCY, sXCZ, sYCX, sYCY, sYCZ, sZCX, sZCY, sZCZ,
-    sZCrY, sInvZCrY,
+    sZCrY, sInvZCrY, sSWAPCX, sInvSWAPCX, sCZSWAP, sCXSWAP, sISWAP, sInvISWAP,
+    sSQRTZZ, sInvSQRTZZ,
     # Misc Ops
     SparseGate,
     sMX, sMY, sMZ, PauliMeasurement, Reset, sMRX, sMRY, sMRZ,

src/symbolic_cliffords.jl

@@ -308,6 +308,16 @@ macro qubitop2(name, kernel)
 end
 #                 x1   z1      x2      z2
 @qubitop2 SWAP   (x2 , z2    , x1    , z1    , false)
+
+@qubitop2 SWAPCX    (x2    , z2⊻z1 , x2⊻x1 , z1    , ~iszero((x1 & z1 & x2 & z2) | (~x1 & z1 & x2 & ~z2)))
+@qubitop2 InvSWAPCX (x2⊻x1 , z2    , x1    , z2⊻z1 , ~iszero((x1 & z1 & x2 & z2) | ( x1 &~z1 &~x2 &  z2)))
+
+@qubitop2 ISWAP    (x2       , x1⊻z2⊻x2 , x1       , x1⊻x2⊻z1 , ~iszero((x1 & z1 & ~x2) | (~x1 & x2 & z2)))
+@qubitop2 InvISWAP (x2       , x1⊻z2⊻x2 , x1       , x1⊻x2⊻z1 , ~iszero((x1 &~z1 & ~x2) | (~x1 & x2 &~z2)))
+
+@qubitop2 CZSWAP (x2    , z2⊻x1 , x1    , x2⊻z1 , ~iszero((x1 & ~z1 & x2 & z2) | (x1 & z1 & x2 & ~z2)))
+@qubitop2 CXSWAP (x2⊻x1 , z2    , x1    , z2⊻z1 , ~iszero((x1 & ~z1 &~x2 & z2) | (x1 & z1 & x2 &  z2)))
+
 @qubitop2 CNOT   (x1 , z1⊻z2 , x2⊻x1 , z2    , ~iszero( (x1 & z1 & x2 & z2)  | (x1 & z2 &~(z1|x2)) ))
 @qubitop2 CPHASE (x1 , z1⊻x2 , x2    , z2⊻x1 , ~iszero( (x1 & z1 & x2 &~z2)  | (x1 &~z1 & x2 & z2) ))
 
@@ -326,6 +336,9 @@ end
 @qubitop2 ZCrY    (x1, x1⊻z1⊻x2⊻z2, x1⊻x2, x1⊻z2, ~iszero((x1 &~z1 & x2) | (x1 & ~z1 & ~z2) | (x1 & x2 & ~z2)))
 @qubitop2 InvZCrY (x1, x1⊻z1⊻x2⊻z2, x1⊻x2, x1⊻z2, ~iszero((x1 & z1 &~x2) | (x1 &  z1 &  z2) | (x1 &~x2 &  z2)))
 
+@qubitop2 SQRTZZ    (x1       , x1⊻x2⊻z1 , x2       , x1⊻z2⊻x2 , ~iszero((x1 & z1 & ~x2) | (~x1 & x2 & z2)))
+@qubitop2 InvSQRTZZ (x1       , x1⊻x2⊻z1 , x2       , x1⊻z2⊻x2 , ~iszero((x1 &~z1 & ~x2) | (~x1 & x2 &~z2)))
+
 #=
 To get the boolean formulas for the phase, it is easiest to first write down the truth table for the phase:
 for i in 0:15
@@ -370,20 +383,28 @@ function Base.show(io::IO, op::AbstractTwoQubitOperator)
     end
 end
 
-LinearAlgebra.inv(op::sSWAP) = sSWAP(op.q1, op.q2)
-LinearAlgebra.inv(op::sCNOT) = sCNOT(op.q1, op.q2)
-LinearAlgebra.inv(op::sCPHASE) = sCPHASE(op.q1, op.q2)
-LinearAlgebra.inv(op::sZCX) = sZCX(op.q1, op.q2)
-LinearAlgebra.inv(op::sZCY) = sZCY(op.q1, op.q2)
-LinearAlgebra.inv(op::sZCZ) = sZCZ(op.q1, op.q2)
-LinearAlgebra.inv(op::sXCX) = sXCX(op.q1, op.q2)
-LinearAlgebra.inv(op::sXCY) = sXCY(op.q1, op.q2)
-LinearAlgebra.inv(op::sXCZ) = sXCZ(op.q1, op.q2)
-LinearAlgebra.inv(op::sYCX) = sYCX(op.q1, op.q2)
-LinearAlgebra.inv(op::sYCY) = sYCY(op.q1, op.q2)
-LinearAlgebra.inv(op::sYCZ) = sYCZ(op.q1, op.q2)
-LinearAlgebra.inv(op::sZCrY) = sInvZCrY(op.q1, op.q2)
-LinearAlgebra.inv(op::sInvZCrY) = sZCrY(op.q1, op.q2)
+LinearAlgebra.inv(op::sSWAP)      = sSWAP(op.q1, op.q2)
+LinearAlgebra.inv(op::sCNOT)      = sCNOT(op.q1, op.q2)
+LinearAlgebra.inv(op::sCPHASE)    = sCPHASE(op.q1, op.q2)
+LinearAlgebra.inv(op::sZCX)       = sZCX(op.q1, op.q2)
+LinearAlgebra.inv(op::sZCY)       = sZCY(op.q1, op.q2)
+LinearAlgebra.inv(op::sZCZ)       = sZCZ(op.q1, op.q2)
+LinearAlgebra.inv(op::sXCX)       = sXCX(op.q1, op.q2)
+LinearAlgebra.inv(op::sXCY)       = sXCY(op.q1, op.q2)
+LinearAlgebra.inv(op::sXCZ)       = sXCZ(op.q1, op.q2)
+LinearAlgebra.inv(op::sYCX)       = sYCX(op.q1, op.q2)
+LinearAlgebra.inv(op::sYCY)       = sYCY(op.q1, op.q2)
+LinearAlgebra.inv(op::sYCZ)       = sYCZ(op.q1, op.q2)
+LinearAlgebra.inv(op::sZCrY)      = sInvZCrY(op.q1, op.q2)
+LinearAlgebra.inv(op::sInvZCrY)   = sZCrY(op.q1, op.q2)
+LinearAlgebra.inv(op::sSWAPCX)    = sInvSWAPCX(op.q1, op.q2)
+LinearAlgebra.inv(op::sInvSWAPCX) = sSWAPCX(op.q1, op.q2)
+LinearAlgebra.inv(op::sCZSWAP)    = sCZSWAP(op.q1, op.q2)
+LinearAlgebra.inv(op::sCXSWAP)    = sSWAPCX(op.q1, op.q2)
+LinearAlgebra.inv(op::sISWAP)     = sInvISWAP(op.q1, op.q2)
+LinearAlgebra.inv(op::sInvISWAP)  = sISWAP(op.q1, op.q2)
+LinearAlgebra.inv(op::sSQRTZZ)    = sInvSQRTZZ(op.q1, op.q2)
+LinearAlgebra.inv(op::sInvSQRTZZ) = sSQRTZZ(op.q1, op.q2)
 
 ##############################
 # Functions that perform direct application of common operators without needing an operator instance

test/test_symcliff.jl

@@ -99,6 +99,19 @@
             @test CliffordOperator(inv(sXCZ(n₁, n₂)), n₁) == inv(CliffordOperator(sCNOT(n₂, n₁), n₁))
             @test CliffordOperator(inv(sZCrY(n₁, n₂)), n₁) == inv(CliffordOperator(sZCrY(n₁, n₂), n₁))
             @test CliffordOperator(inv(sInvZCrY(n₁, n₂)), n₁) == inv(CliffordOperator(sInvZCrY(n₁, n₂), n₁))
+            @test CliffordOperator(inv(sCXSWAP(n₁, n₂)), n₁) == inv(CliffordOperator(sInvSWAPCX(n₁, n₂), n₁))
         end
     end
+
+    @testset "Consistency check with STIM conventions" begin
+        # see https://github.com/quantumlib/Stim/blob/main/doc/gates.md
+        @test CliffordOperator(sSWAPCX)    == C"IX XX ZZ ZI"
+        @test CliffordOperator(sInvSWAPCX) == C"XX XI IZ ZZ"
+        @test CliffordOperator(sCZSWAP)    == C"ZX XZ IZ ZI"
+        @test CliffordOperator(sCXSWAP)    == C"XX XI IZ ZZ"
+        @test CliffordOperator(sISWAP)     == C"ZY YZ IZ ZI"
+        @test CliffordOperator(sInvISWAP)  == C"-ZY -YZ IZ ZI"
+        @test CliffordOperator(sSQRTZZ)    == C"YZ ZY ZI IZ"
+        @test CliffordOperator(sInvSQRTZZ) == C"-YZ -ZY ZI IZ"
+    end
 end