* Add documentation on clinks

docs/source/tutorial/section4_NetworkConfiguration.rst

@@ -91,7 +91,7 @@ We start with the simplest configuration file, one without any noise:
     :language: yaml
     :caption: examples/tutorial/4.2_network-configuration/1_perfect.yaml
 
-The network requires two types of objects to be specified: stacks and links.
+The network requires three types of objects to be specified: stacks, links and clinks.
 
 Stacks are the end nodes of the network and run applications.
 Each stack requires a name, this name will be used by the links and applications for reference.
@@ -101,10 +101,16 @@ The various stack types are discussed in :ref:`label_stack_types`.
 
 Links connect the stacks with a way of generating EPR pairs between the two nodes.
 A link requires references to the two stacks it is to connect.
-This is done by registering the names of the stacks in the fields ``node1`` and ``node2``.
+This is done by registering the names of the stacks in the fields ``stack1`` and ``stack2``.
 The model type of the link is specified using the ``typ`` field.
 The various settings for the model are defined inside ``cfg``.
 
+Clinks are shorthand for classical links. These are similar to links, but for classical message communication.
+A clink requires references to the two stacks it is to connect with a classical link.
+This is done by registering the names of the stacks in the fields ``stack1`` and ``stack2``.
+The model type of the clink is specified using the ``typ`` field.
+The various settings for the model are defined inside ``cfg``.
+
 .. _label_stack_types:
 
 Stack types
@@ -203,6 +209,31 @@ The heralded link uses the double click model as developed and described by this
     :language: yaml
     :caption: examples/tutorial/4.2_network-configuration/5_heralded_link.yaml
 
+Clink types
++++++++++++
+
+instant clink
+----------------
+The instant clink is a classical link model where all classical communication is instant.
+It does not have any configuration options.
+
+.. literalinclude:: ../../../examples/tutorial/4.2_network-configuration/1_perfect.yaml
+    :language: yaml
+    :caption: examples/tutorial/4.2_network-configuration/1_perfect.yaml
+    :lines: 19-22
+
+
+default clink
+----------------
+The default clink is a classical link model where classical communication is delayed by exactly the delay specified in
+the configuration.
+
+.. literalinclude:: ../../../examples/tutorial/4.2_network-configuration/6_default.yaml
+    :language: yaml
+    :caption: examples/tutorial/4.2_network-configuration/1_perfect.yaml
+    :lines: 19-24
+
+
 Parameter sweeping
 =====================
 Often it will be desired to simulate not a single network configuration, but a range of parameters.

examples/tutorial/4.2_network-configuration/6_default.yaml

@@ -0,0 +1,24 @@
+# A 2 node network, perfect except for classical communication using a default model that has communication delay
+stacks:
+  - name: Alice
+    qdevice_typ: generic
+    qdevice_cfg:
+      dummy: null
+  - name: Bob
+    qdevice_typ: generic
+    qdevice_cfg:
+      dummy: null
+
+links:
+  - stack1: Alice
+    stack2: Bob
+    typ: perfect
+    cfg:
+      dummy: null
+
+clinks:
+  - stack1: Alice
+    stack2: Bob
+    typ: default
+    cfg:
+      delay: 20

squidasm/run/stack/build.py

@@ -1,12 +1,13 @@
 from __future__ import annotations
 
-from typing import Dict
+from typing import Dict, TYPE_CHECKING
 
 from netsquid_netbuilder.base_configs import NetworkConfig
 from netsquid_netbuilder.builder.network_builder import NetworkBuilder, NodeBuilder
 from netsquid_netbuilder.run import get_default_builder
 
-from squidasm.sim.stack.stack import StackNode
+if TYPE_CHECKING:
+    from squidasm.sim.stack.stack import StackNode
 
 
 class StackNodeBuilder(NodeBuilder):