Quantum Circuit Synthesis

The main functionality for synthesizing quantum circuits is provided by the synthesize_clifford() and the optimize_clifford() methods.

synthesize_clifford(target_tableau, initial_tableau=None, include_destabilizers=False, **kwargs)[source]

Synthesize a Clifford circuit from a given tableau starting from an (optional) initial tableau.

Parameters:

  • target_tableau (str | Clifford | PauliList | Tableau) – The target tableau to synthesize. If a string is given, it is interpreted as a semicolon separated binary matrix or a list of Pauli strings. The Pauli strings follow the same format as in Stim. If a Clifford or a PauliList is given, it is converted to a Tableau. If a Tableau is given, it is used directly.

  • initial_tableau (str | Clifford | PauliList | Tableau | None) – The initial tableau to start from. If a string is given, it is interpreted as a semicolon separated binary matrix or a list of Pauli strings. If a Clifford or a PauliList is given, it is converted to a Tableau. If a Tableau is given, it is used directly. If no initial tableau is given, the synthesis starts from the identity tableau.

  • include_destabilizers (bool) – Flag to set whether destabilizers should be considered in the synthesis

  • **kwargs (Any) – Additional keyword arguments to configure the synthesis. See SynthesisConfiguration for a list of available options.

Returns:

tuple[QuantumCircuit, SynthesisResults] – A tuple containing the synthesized circuit and the synthesis results.

optimize_clifford(circuit, initial_tableau=None, include_destabilizers=False, **kwargs)[source]

Optimize a Clifford circuit starting from an (optional) initial tableau.

Parameters:

  • circuit (str | QuantumCircuit | QuantumComputation) – The circuit to optimize. If a string is given, it is interpreted as a QASM string or a filename. If a QuantumCircuit is given, it is converted to a QuantumComputation. If a QuantumComputation is given, it is used as is.

  • initial_tableau (str | Clifford | PauliList | Tableau | None) – The initial tableau to start from. If a string is given, it is interpreted as a semicolon separated binary matrix or a list of Pauli strings. If a Clifford is given or a PauliList is given, it is converted to a Tableau. If a Tableau is given, it is used directly. If no initial tableau is given, the synthesis starts from the identity tableau.

  • include_destabilizers (bool) – Flag to set whether destabilizers should be considered in the synthesis

  • **kwargs (Any) – Additional keyword arguments to configure the synthesis. See SynthesisConfiguration for a list of available options.

Returns:

tuple[QuantumCircuit, SynthesisResults] – A tuple containing the optimized circuit and the synthesis results.

Synthesis Configuration

The following classes provide a more explicit way of initializing the respective parameters of the synthesize_clifford and the optimize_clifford method. Instead of setting parameters via str members, they can be set with Enumeration.member where Enumeration is the enumeration class.

class TargetMetric

Members:

gates : Optimize gate count.

two_qubit_gates : Optimize two-qubit gate count.

depth : Optimize circuit depth.

class Verbosity

Members:

none : No output.

fatal : Only show fatal errors.

error : Show errors.

warning : Show warnings.

info : Show general information.

debug : Show additional debug information.

verbose : Show all information.

The SynthesisConfiguration class is used to provide several parameters to the synthesize_clifford and the optimize_clifford method. The following table lists the parameters and their default values.

class SynthesisConfiguration

Configuration options for the MQT QMAP Clifford synthesis tool.

property dump_intermediate_results

Dump intermediate results of the synthesis process. Defaults to false.

property gate_limit_factor

Factor by which the gate limit is increased when trying to find a better solution for the two-qubit gate optimization. Defaults to 1.1.

property heuristic

Use heuristic to synthesize the circuit. This method synthesizes shallow intermediate circuits and combines them. Defaults to false.

property initial_timestep_limit

Initial timestep limit for the Clifford synthesis. Defaults to 0, which implies that the initial timestep limit is determined automatically.

property intermediate_results_path

Path to the directory where intermediate results should be dumped. Defaults to ./. The path needs to include a path separator at the end.

json(self: mqt.qmap.pyqmap.SynthesisConfiguration) → json

Returns a JSON-style dictionary of all the information present in the Configuration

Use liner search instead of binary search scheme for finding the optimum. Defaults to false.

property minimal_timesteps

Minimal timestep considered for the Clifford synthesis. This option limits the lower bound of the interval in which the binary search method looks for solutions. Set this if you know a lower bound for the circuit depth. Defaults to 0, which implies that no lower bound for depth is known.

property minimize_gates_after_depth_optimization

Depth optimization might produce a circuit with more gates than necessary. This option enables an additional run of the synthesizer to minimize the overall number of gates. Defaults to false.

property minimize_gates_after_two_qubit_gate_optimization

Two-qubit gate optimization might produce a circuit with more gates than necessary. This option enables an additional run of the synthesizer to minimize the overall number of gates. Defaults to false.

property n_threads_heuristic

Maximum number of threads used for the heuristic optimizer. Defaults to the number of available threads on the system.

property solver_parameters

Parameters to be passed to Z3 as dict[str, bool | int | float | str]

property split_size

Size of subcircuits used in heuristic. Defaults to 5.

property target_metric

Target metric for the Clifford synthesis. Defaults to gates.

property try_higher_gate_limit_for_two_qubit_gate_optimization

When optimizing two-qubit gates, the synthesizer might fail to find an optimal solution for a certain timestep limit, but there might be a better solution for some higher timestep limit. This option enables an additional run of the synthesizer with a higher gate limit. Defaults to false.

property use_maxsat

Use MaxSAT to solve the synthesis problem or to really on the binary search scheme for finding the optimum. Defaults to false.

property use_symmetry_breaking

Use symmetry breaking clauses to speed up the synthesis process. Defaults to true.

property verbosity

Verbosity level for the synthesis process. Defaults to ‘warning’.