Executing your first program

Before jumping into the deeper workings of QAT, let’s run a simple program against an echo engine. This doesn’t do much useful execution, but compiling and executing against it is very simple, and fortunately, compiling and executing against actual hardware or useful simulators isn’t much more complicated.

We start by defining in a hardware loader, which is used to load in a hardware model by different means. This particular loader just creates a mock-up of hardware with a ring topology.

from qat.model.loaders.lucy import LucyModelLoader

loader = LucyModelLoader(qubit_count=8)

We use the model to constuct an echo pipeline that compiles and executes using an “echo mode”

from qat.pipelines.waveform import EchoPipeline, PipelineConfig

config = PipelineConfig(name="echo_pipeline")
pipeline = EchoPipeline(loader=loader, config=config)

We will run a QASM2 program that creates and measures a bell state.

from compiler_config.config import CompilerConfig, QuantumResultsFormat

qasm_str = """
OPENQASM 2.0;
include "qelib1.inc";
qreg q[2];
creg c[2];
h q[0];
cx q[0], q[1];
measure q -> c;
"""
config = CompilerConfig(results_format=QuantumResultsFormat().binary_count())

Now we can compile and execute the program against the pipeline

from qat import QAT

core = QAT()
results, metrics = core.run(qasm_str, compiler_config=config, pipeline=pipeline)
print(results)

{'c': {'11': 1000}}

Setting up using QAT config

QAT also provides a way to conveniently set up compilation and execution pipelines as a configurational YAML file. If we write a file called qatconfig.yaml with the following contents:

HARDWARE:
- name: lucy
  type: qat.model.loaders.lucy.LucyModelLoader
  config:
    qubit_count: 8

PIPELINES:
- name: echo_pipeline
  pipeline: qat.pipelines.waveform.EchoPipeline
  hardware_loader: lucy

We can then load it in to QAT and execute as before:

from qat import QAT
from compiler_config.config import CompilerConfig, QuantumResultsFormat

# Set up compile and execute pipelines
core = QAT(qatconfig="qatconfig.yaml")

# Set up the input program
qasm_str = """
OPENQASM 2.0;
include "qelib1.inc";
qreg q[2];
creg c[2];
h q[0];
cx q[0], q[1];
measure q -> c;
"""
config = CompilerConfig(repeats=1000, results_format=QuantumResultsFormat().binary_count())

# Execute using QAT
results, metrics = core.run(qasm_str, compiler_config=config, pipeline="echo_pipeline")