GitHub

Register Networks

A RegisterNet joins is an undirected graph with one Register per vertex.

Construct a Network

Give RegisterNet a SimpleGraph and one register for each vertex:

using QuantumSavory, Graphs

graph = path_graph(3)
net = RegisterNet(graph, [Register(2) for _ in 1:3])

If you omit the graph, RegisterNet makes a chain:

net = RegisterNet([Register(2), Register(2), Register(2)])

Use the Supported Graph Interface

RegisterNet supports a small part of the Graphs.jl API directly:

OperationResult
vertices(net)Vertex identifiers
edges(net)Undirected graph edges
neighbors(net, i)Vertices adjacent to i
nv(net)Number of vertices
ne(net)Number of edges
adjacency_matrix(net)Graph adjacency matrix

For example:

collect(vertices(net))
collect(edges(net))
neighbors(net, 2)

A RegisterNet is not a subtype of Graphs.AbstractGraph. Do not assume that other Graphs.jl functions accept it. Keep the graph used for construction when you need the full Graphs.jl API. Treat the topology as fixed after construction.

Index Registers and Slots

One index selects a register. A second index selects a slot and returns a RegRef:

node = net[2]        # a Register
slot = net[2][1]     # a RegRef
slot == net[2, 1]    # compact form

Colon indexing selects the same layer from all nodes:

ExpressionResult
net[:]All registers
net[:, j]Slot j from every register

Every register must have slot j for net[:, j] to succeed. After you have a RegRef, use the operations in the Register Interface API.

Configure Names and Labels

Use name for the network display name. Use names for register display names:

net = RegisterNet([Register(2) for _ in 1:3];
    name="line", names=["left", "middle", "right"])

These names appear in register and protocol displays. They do not change the integer vertex identifiers.

Other static metadata uses the following indexing scheme:

net[1, :description] = "end node"
net[(1, 2), :length] = 20.0  # undirected edge
net[1 => 2, :loss] = 0.1     # directed edge

For undirected metadata, (1, 2) and (2, 1) select the same entry. For directed metadata, 1 => 2 and 2 => 1 select separate entries. A metadata read requires the key to exist.

For more sophisticated treatment of metadata, especially if it is used by protocols being simulated in the network, consult the tagging and querying infrastructure.

The classical_delay and quantum_delay keywords set the direct-link delays. A number applies to both directions of every edge:

net = RegisterNet(path_graph(3), [Register(2) for _ in 1:3];
    classical_delay=0.2, quantum_delay=0.1)

A two-argument callable sets a delay for each direction:

delay(src, dst) = src < dst ? 0.1 : 0.2
net = RegisterNet(path_graph(3), [Register(2) for _ in 1:3];
    classical_delay=delay)

The constructor calls delay(src, dst) and delay(dst, src) separately for each graph edge. The delay advances simulation time. It does not wait in wall clock time.

Classical channels can forward a message across more than one edge. Each hop uses its configured delay. Quantum channels are direct-edge channels. Read Classical Messaging and Buffers for channel and message-buffer use.

Where to Go Next