Defining your own gate sets

OpenQASM3 has two built-in gates – U and gphase. Combined with gate modifiers, these two are enough to define a universal gate set for quantum computation.

OpenQASM3 also offers a standard library of gates, all defined in terms of the two built-in gates, in stdgates.inc. Quasar.jl provides a copy of stdgates.inc in its test/ directory, which you can import with:

include "stdgates.inc";

However, many quantum computers and simulators have different built-in gates, so-called "native gates", which they can implement without reference to gphase or U. You can provide your own built-in gate set to Quasar.jl to ensure that the output circuit instructions are in your "gate dialect".

In Quasar.jl, you can create a function which takes no arguments and returns a Dict{String, BuiltinGateDefinition}. The keys are the names of your built-in gates (e.g. "msaa") and a BuiltinGateDefinition has the following fields:

  • name::String – the name of the gate
  • arguments::Vector{String} – the names of the gate's arguments, if any (can be empty)
  • qubit_targets::Vector{String} – the names of the gate's target(s).
  • body::CircuitInstruction – the single CircuitInstruction which defines the gate

So, for example, if the Pauli X gate x and the X rotation gate Rx are built-in gates, you could create the function:

my_builtin_gates() = Dict(
    "x"=>BuiltinGateDefinition("x", String[], ["a"], (type="x", arguments=InstructionArgument[], targets=[0], controls=Pair{Int,Int}[], exponent=1.0)), 
    "rx"=>BuiltinGateDefinition("rx", ["θ"], ["a"], (type="rx", arguments=InstructionArgument[θ], targets=[0], controls=Pair{Int,Int}[], exponent=1.0)),
)

You can provide this definition to Quasar.jl by updating the reference builtin_gates:

using Quasar
Quasar.builtin_gates[] = my_builtin_gates