diff --git a/src/MetagraphOptimization.jl b/src/MetagraphOptimization.jl
index 874de89..6c1ff9d 100644
--- a/src/MetagraphOptimization.jl
+++ b/src/MetagraphOptimization.jl
@@ -19,7 +19,6 @@ export AbstractTask
 export AbstractComputeTask
 export AbstractDataTask
 export DataTask
-export FusedComputeTask
 export PossibleOperations
 export GraphProperties
 
@@ -44,7 +43,6 @@ export is_valid, is_scheduled
 # graph operation related
 export Operation
 export AppliedOperation
-export NodeFusion
 export NodeReduction
 export NodeSplit
 export push_operation!
@@ -88,7 +86,7 @@ export GlobalMetricEstimator, CDCost
 
 # optimization
 export AbstractOptimizer, GreedyOptimizer, RandomWalkOptimizer
-export ReductionOptimizer, SplitOptimizer, FusionOptimizer
+export ReductionOptimizer, SplitOptimizer
 export optimize_step!, optimize!
 export fixpoint_reached, optimize_to_fixpoint!
 
@@ -166,7 +164,6 @@ include("optimization/interface.jl")
 include("optimization/greedy.jl")
 include("optimization/random_walk.jl")
 include("optimization/reduce.jl")
-include("optimization/fuse.jl")
 include("optimization/split.jl")
 
 include("models/interface.jl")
diff --git a/src/estimator/global_metric.jl b/src/estimator/global_metric.jl
index c662ccb..e3f0194 100644
--- a/src/estimator/global_metric.jl
+++ b/src/estimator/global_metric.jl
@@ -10,8 +10,7 @@ Representation of a [`DAG`](@ref)'s cost as estimated by the [`GlobalMetricEstim
 
 
 !!! note
-    Note that the `computeIntensity` doesn't necessarily make sense in the context of only operation costs. 
-    For example, for node fusions this will always be 0, since the computeEffort is zero. 
+    Note that the `computeIntensity` doesn't necessarily make sense in the context of only operation costs.
     It will still work as intended when adding/subtracting to/from a `graph_cost` estimate.
 """
 const CDCost = NamedTuple{(:data, :computeEffort, :computeIntensity), Tuple{Float64, Float64, Float64}}
@@ -55,10 +54,6 @@ function graph_cost(estimator::GlobalMetricEstimator, graph::DAG)
     )::CDCost
 end
 
-function operation_effect(estimator::GlobalMetricEstimator, graph::DAG, operation::NodeFusion)
-    return (data = -data(operation.input[2].task), computeEffort = 0.0, computeIntensity = 0.0)::CDCost
-end
-
 function operation_effect(estimator::GlobalMetricEstimator, graph::DAG, operation::NodeReduction)
     s = length(operation.input) - 1
     return (
diff --git a/src/graph/mute.jl b/src/graph/mute.jl
index 1ea56a2..082ab16 100644
--- a/src/graph/mute.jl
+++ b/src/graph/mute.jl
@@ -169,66 +169,6 @@ function remove_edge!(graph::DAG, node1::Node, node2::Node; track = true, invali
     return nothing
 end
 
-function replace_children!(task::FusedComputeTask, before, after)
-    replacedIn1 = length(findall(x -> x == before, task.t1_inputs))
-    replacedIn2 = length(findall(x -> x == before, task.t2_inputs))
-
-    #@assert replacedIn1 >= 1 || replacedIn2 >= 1 "Nothing to replace while replacing $before with $after in $(task.t1_inputs...) and $(task.t2_inputs...)"
-
-    replace!(task.t1_inputs, before => after)
-    replace!(task.t2_inputs, before => after)
-
-    # recursively descend down the tree, but only in the tasks where we're replacing things
-    if replacedIn1 > 0
-        replace_children!(task.first_task, before, after)
-    end
-    if replacedIn2 > 0
-        replace_children!(task.second_task, before, after)
-    end
-
-    return nothing
-end
-
-function replace_children!(task::AbstractTask, before, after)
-    return nothing
-end
-
-function update_child!(graph::DAG, n::Node, child_before::Symbol, child_after::Symbol; track = true)
-    # only need to update fused compute tasks
-    if !(typeof(task(n)) <: FusedComputeTask)
-        return nothing
-    end
-
-    taskBefore = copy(task(n))
-
-    #=if !((child_before in task(n).t1_inputs) || (child_before in task(n).t2_inputs))
-        println("------------------ Nothing to replace!! ------------------")
-        child_ids = Vector{String}()
-        for child in children(n)
-            push!(child_ids, "$(child.id)")
-        end
-        println("From $(child_before) to $(child_after) in $n with children $(child_ids)")
-        @assert false
-    end=#
-
-    replace_children!(task(n), child_before, child_after)
-
-    #=if !((child_after in task(n).t1_inputs) || (child_after in task(n).t2_inputs))
-        println("------------------ Did not replace anything!! ------------------")
-        child_ids = Vector{String}()
-        for child in children(n)
-            push!(child_ids, "$(child.id)")
-        end
-        println("From $(child_before) to $(child_after) in $n with children $(child_ids)")
-        @assert false
-    end=#
-
-    # keep track
-    if (track)
-        push!(graph.diff.updatedChildren, (n, taskBefore))
-    end
-end
-
 """
     get_snapshot_diff(graph::DAG)
 
diff --git a/src/graph/validate.jl b/src/graph/validate.jl
index d731906..e8fa449 100644
--- a/src/graph/validate.jl
+++ b/src/graph/validate.jl
@@ -40,19 +40,11 @@ function is_valid(graph::DAG)
     for ns in graph.possibleOperations.nodeSplits
         @assert is_valid(graph, ns)
     end
-    for nf in graph.possibleOperations.nodeFusions
-        @assert is_valid(graph, nf)
-    end
 
     for node in graph.dirtyNodes
         @assert node in graph "Dirty Node is not part of the graph!"
         @assert ismissing(node.nodeReduction) "Dirty Node has a NodeReduction!"
         @assert ismissing(node.nodeSplit) "Dirty Node has a NodeSplit!"
-        if (typeof(node) <: DataTaskNode)
-            @assert ismissing(node.nodeFusion) "Dirty DataTaskNode has a Node Fusion!"
-        elseif (typeof(node) <: ComputeTaskNode)
-            @assert isempty(node.nodeFusions) "Dirty ComputeTaskNode has Node Fusions!"
-        end
     end
 
     @assert is_connected(graph) "Graph is not connected!"
diff --git a/src/models/physics_models/README.md b/src/models/physics_models/README.md
new file mode 100644
index 0000000..453d5d2
--- /dev/null
+++ b/src/models/physics_models/README.md
@@ -0,0 +1,3 @@
+## Deprecation Warning
+
+These models are deprecated and should not be used anymore. They will be dropped entirely soon.
diff --git a/src/models/physics_models/qed/parse.jl b/src/models/physics_models/qed/parse.jl
index 7b8f6e0..d0f517a 100644
--- a/src/models/physics_models/qed/parse.jl
+++ b/src/models/physics_models/qed/parse.jl
@@ -1,5 +1,3 @@
-
-# TODO generalize this somehow, probably using AllSpin/AllPol as defaults
 """
     parse_process(string::AbstractString, model::QEDModel)
 
@@ -8,10 +6,10 @@ Parse a string representation of a process, such as "ke->ke" into the correspond
 function parse_process(
     str::AbstractString,
     model::QEDModel,
-    inphpol::AbstractDefinitePolarization,
-    inelspin::AbstractDefiniteSpin,
-    outphpol::AbstractDefinitePolarization,
-    outelspin::AbstractDefiniteSpin,
+    inphpol::AbstractDefinitePolarization = PolX(),
+    inelspin::AbstractDefiniteSpin = SpinUp(),
+    outphpol::AbstractDefinitePolarization = PolX(),
+    outelspin::AbstractDefiniteSpin = SpinUp(),
 )
     inParticles = Dict(
         ParticleStateful{Incoming, Photon, SFourMomentum} => 0,
diff --git a/src/operation/type.jl b/src/operation/type.jl
index 606b101..eb37040 100644
--- a/src/operation/type.jl
+++ b/src/operation/type.jl
@@ -20,45 +20,6 @@ See also: [`revert_operation!`](@ref).
 """
 abstract type AppliedOperation end
 
-"""
-    NodeFusion <: Operation
-
-The NodeFusion operation. Represents the fusing of a chain of compute node -> data node -> compute node.
-
-After the node fusion is applied, the graph has 2 fewer nodes and edges, and a new [`FusedComputeTask`](@ref) with the two input compute nodes as parts.
-
-# Requirements for successful application
-
-A chain of (n1, n2, n3) can be fused if:
-- All nodes are in the graph.
-- (n1, n2) is an edge in the graph.
-- (n2, n3) is an edge in the graph.
-- n2 has exactly one parent (n3) and exactly one child (n1).
-- n1 has exactly one parent (n2).
-
-[`is_valid_node_fusion_input`](@ref) can be used to `@assert` these requirements.
-
-See also: [`can_fuse`](@ref)
-"""
-struct NodeFusion{TaskType1 <: AbstractComputeTask, TaskType2 <: AbstractDataTask, TaskType3 <: AbstractComputeTask} <:
-       Operation
-    input::Tuple{ComputeTaskNode{TaskType1}, DataTaskNode{TaskType2}, ComputeTaskNode{TaskType3}}
-end
-
-"""
-    AppliedNodeFusion <: AppliedOperation
-
-The applied version of the [`NodeFusion`](@ref).
-"""
-struct AppliedNodeFusion{
-    TaskType1 <: AbstractComputeTask,
-    TaskType2 <: AbstractDataTask,
-    TaskType3 <: AbstractComputeTask,
-} <: AppliedOperation
-    operation::NodeFusion{TaskType1, TaskType2, TaskType3}
-    diff::Diff
-end
-
 """
     NodeReduction <: Operation
 
diff --git a/src/utility.jl b/src/utility.jl
index a610663..0e7582d 100644
--- a/src/utility.jl
+++ b/src/utility.jl
@@ -74,9 +74,6 @@ function mem(graph::DAG)
     size += sizeof(graph.operationsToApply)
 
     size += sizeof(graph.possibleOperations)
-    for op in graph.possibleOperations.nodeFusions
-        size += mem(op)
-    end
     for op in graph.possibleOperations.nodeReductions
         size += mem(op)
     end
diff --git a/test/runtests.jl b/test/runtests.jl
index 277f5de..fa37b10 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,6 +1,5 @@
 using SafeTestsets
 
-#=
 @safetestset "Utility Unit Tests                  " begin
     include("unit_tests_utility.jl")
 end
@@ -19,11 +18,9 @@ end
 @safetestset "ABC-Model Unit Tests                " begin
     include("unit_tests_abcmodel.jl")
 end
-=#
 @safetestset "QED-Model Unit Tests                " begin
     include("unit_tests_qedmodel.jl")
 end
-#=
 @safetestset "QED Feynman Diagram Generation Tests" begin
     include("unit_tests_qed_diagrams.jl")
 end
@@ -42,4 +39,3 @@ end
 @safetestset "Known Graph Tests                   " begin
     include("known_graphs.jl")
 end
-=#
\ No newline at end of file
diff --git a/test/unit_tests_abcmodel.jl b/test/unit_tests_abcmodel.jl
index cff7ecc..1dacdef 100644
--- a/test/unit_tests_abcmodel.jl
+++ b/test/unit_tests_abcmodel.jl
@@ -1,5 +1,5 @@
 using MetagraphOptimization
-using QEDbase
+using QEDcore
 
 import MetagraphOptimization.interaction_result
 
diff --git a/test/unit_tests_qedmodel.jl b/test/unit_tests_qedmodel.jl
index 9a48050..ad7bec5 100644
--- a/test/unit_tests_qedmodel.jl
+++ b/test/unit_tests_qedmodel.jl
@@ -144,32 +144,7 @@ end
 
         for i in 1:100
             input = gen_process_input(process)
-            @test length(input.inFerms) ==
-                  get(process.inParticles, ParticleStateful{Incoming, Electron, SFourMomentum}, 0)
-            @test length(input.inAntiferms) ==
-                  get(process.inParticles, ParticleStateful{Incoming, Positron, SFourMomentum}, 0)
-            @test length(input.inPhotons) ==
-                  get(process.inParticles, ParticleStateful{Incoming, Photon, SFourMomentum}, 0)
-            @test length(input.outFerms) ==
-                  get(process.outParticles, ParticleStateful{Outgoing, Electron, SFourMomentum}, 0)
-            @test length(input.outAntiferms) ==
-                  get(process.outParticles, ParticleStateful{Outgoing, Positron, SFourMomentum}, 0)
-            @test length(input.outPhotons) ==
-                  get(process.outParticles, ParticleStateful{Outgoing, Photon, SFourMomentum}, 0)
-
-            @test isapprox(
-                sum([
-                    getfield.(input.inFerms, :momentum)...,
-                    getfield.(input.inAntiferms, :momentum)...,
-                    getfield.(input.inPhotons, :momentum)...,
-                ]),
-                sum([
-                    getfield.(input.outFerms, :momentum)...,
-                    getfield.(input.outAntiferms, :momentum)...,
-                    getfield.(input.outPhotons, :momentum)...,
-                ]);
-                atol = sqrt(eps()),
-            )
+            @test isapprox(sum(momenta(input, Incoming())), sum(momenta(input, Outgoing())); atol = sqrt(eps()))
         end
     end
 end