diff --git a/Project.toml b/Project.toml
index b505d9d..9e2539d 100644
--- a/Project.toml
+++ b/Project.toml
@@ -39,7 +39,7 @@ PrecompileTools = "1"
 QuantumClifford = "0.8"
 QuantumInterface = "0.3.0"
 QuantumOptics = "1.0.5"
-QuantumOpticsBase = "0.4"
+QuantumOpticsBase = "0.4.16"
 QuantumSymbolics = "0.2.4"
 Reexport = "1.2.2"
 ResumableFunctions = "0.6.1"
diff --git a/src/CircuitZoo/CircuitZoo.jl b/src/CircuitZoo/CircuitZoo.jl
index 0e0b91a..114fb96 100644
--- a/src/CircuitZoo/CircuitZoo.jl
+++ b/src/CircuitZoo/CircuitZoo.jl
@@ -4,7 +4,8 @@ using QuantumSavory
 using DocStringExtensions
 
 export EntanglementSwap, Purify2to1, Purify2to1Node, Purify3to1, Purify3to1Node,
-    PurifyStringent, PurifyStringentNode, PurifyExpedient, PurifyExpedientNode
+    PurifyStringent, PurifyStringentNode, PurifyExpedient, PurifyExpedientNode,
+    SDDecode, SDEncode
 
 abstract type AbstractCircuit end
 
@@ -851,4 +852,77 @@ function (circuit::PurifyExpedientNode)(purified,sacrificed...)
     [a..., b..., c..., d...]
 end
 
+"""
+$TYPEDEF
+
+Fields:
+
+$FIELDS
+
+The circuit for [Superdense Coding](https://en.wikipedia.org/wiki/Superdense_coding) to encode the 2 (classical) bit message
+to its corresponding Bell pair representation. It takes as argumes a single qubit register containing
+Alice's half of the entangled Bell pair and the 2 bit message Alice intends to send to Bob.
+
+```jldoctest
+julia> regA = Register(1); regB = Register(2);
+
+julia> initialize!((regA[1], regB[1]), (L0⊗L0+L1⊗L1)/√2);
+
+julia> message = [1, 1];
+
+julia> SDEncode()(regA, message);
+```
+
+See also [`SDDecode`](@ref)
+"""
+struct SDEncode <: AbstractCircuit
+end
+
+function (circuit::SDEncode)(reg, message)
+    if message[2] == 1
+        apply!(reg[1], X)
+    end
+    if message[1] == 1
+        apply!(reg[1], Z)
+    end
+end
+
+
+"""
+$TYPEDEF
+
+Fields:
+
+$FIELDS
+
+The circuit for Superdense Coding to decode the 2 (classical) bit message
+using the entangled bell pair stored in the registers regA and regB after Alice's encoding of the first qubit.
+Returns a Tuple of the decoded message.
+
+```jldoctest
+julia> regA = Register(1); regB = Register(2);
+
+julia> initialize!((regA[1], regB[1]), (L0⊗L0+L1⊗L1)/√2);
+
+julia> message = [1, 1];
+
+julia> SDEncode()(regA, message);
+
+julia> SDDecode()(regA, regB)
+(1, 1)
+```
+
+See also [`SDEncode`](@ref)
+"""
+struct SDDecode <: AbstractCircuit
+end
+
+function (circuit::SDDecode)(regA, regB)
+    apply!((regA[1], regB[1]), CNOT)
+    apply!(regA[1], H)
+    b1 = project_traceout!(regA, 1, Z)
+    b2 = project_traceout!(regB, 1, Z)
+    return b1-1, b2-1
+end
+
 end # module
diff --git a/src/backends/quantumoptics/quantumoptics.jl b/src/backends/quantumoptics/quantumoptics.jl
index 6ec699f..d2b081b 100644
--- a/src/backends/quantumoptics/quantumoptics.jl
+++ b/src/backends/quantumoptics/quantumoptics.jl
@@ -37,6 +37,7 @@ function observable(state::Union{<:Ket,<:Operator}, indices, operation)
     expect(op, state)
 end
 
+
 function project_traceout!(state::Union{Ket,Operator},stateindex,psis::Base.AbstractVecOrTuple{<:Ket})
     if nsubsystems(state) == 1 # TODO is there a way to do this in a single function, instead of _overlap vs _project_and_drop
         _overlaps = [_overlap(psi,state) for psi in psis]
diff --git a/test/runtests.jl b/test/runtests.jl
index 1b1e3c0..9bc2c8f 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -28,6 +28,7 @@ println("Starting tests with $(Threads.nthreads()) threads out of `Sys.CPU_THREA
 @doset "observable"
 @doset "noninstant_and_backgrounds_qubit"
 @doset "noninstant_and_backgrounds_qumode"
+@doset "circuitzoo_superdense"
 @doset "circuitzoo_purification"
 @doset "examples"
 get(ENV,"QUANTUMSAVORY_PLOT_TEST","")=="true" && @doset "plotting_cairo"
diff --git a/test/test_circuitzoo_purification.jl b/test/test_circuitzoo_purification.jl
index 2005cbd..0977ffa 100644
--- a/test/test_circuitzoo_purification.jl
+++ b/test/test_circuitzoo_purification.jl
@@ -104,19 +104,15 @@ end
                     r = Register(6, rep())
                     initialize!(r[1:6], bell⊗bell⊗bell)
 
-                    @testset "$leaveout1, $leaveout2" begin
-                        @test Purify3to1(leaveout1, leaveout2)(r[1], r[2], r[3], r[5], r[4], r[6])==true
-                        @test observable(r[1:2], projector(bell))≈1.0
-                    end
+                    @test Purify3to1(leaveout1, leaveout2)(r[1], r[2], r[3], r[5], r[4], r[6])==true
+                    @test observable(r[1:2], projector(bell))≈1.0
                     for error in [:X, :Y, :Z], target in 3:6
                         r = Register(6, rep())
                         for i in 1:3
                             initialize!(r[(2*i-1):(2*i)], bell)
                         end
                         apply!(r[target], Dict(:X=>X, :Y=>Y, :Z=>Z)[error])
-                        @testset "error: $leaveout1, $leaveout2" begin
-                            @test Purify3to1(leaveout1, leaveout2)(r[1], r[2], r[3], r[5], r[4], r[6])==false
-                        end
+                        @test Purify3to1(leaveout1, leaveout2)(r[1], r[2], r[3], r[5], r[4], r[6])==false
                     end
                     for error in [:X, :Y, :Z], target in 1:2
                         r = Register(6, rep())
diff --git a/test/test_circuitzoo_superdense.jl b/test/test_circuitzoo_superdense.jl
new file mode 100644
index 0000000..db3bb35
--- /dev/null
+++ b/test/test_circuitzoo_superdense.jl
@@ -0,0 +1,24 @@
+using QuantumSavory
+using QuantumSavory.CircuitZoo: SDEncode, SDDecode
+using Test
+
+for i in 1:8
+    ## Set up an entangled bell pair
+    ra = Register(1)
+    rb = Register(1)
+
+    initialize!(ra[1], Z1)
+    initialize!(rb[1], Z1)
+
+    apply!(ra[1], H)
+    apply!((ra[1], rb[1]), CNOT)
+
+    # Random 2 bit classical message
+    message = Tuple(rand(0:1, 2))
+
+    # Use the circuits to encode and decode the message
+    SDEncode()(ra, message)
+    rec = SDDecode()(ra, rb)
+
+    @test message == rec
+end