# PhaseOracle¶

class PhaseOracle(expression, synthesizer=None)[source]

Bases: qiskit.circuit.quantumcircuit.QuantumCircuit

Phase Oracle.

The Phase Oracle object constructs circuits for any arbitrary input logical expressions. A logical expression is composed of logical operators & (AND), | (OR), ~ (NOT), and ^ (XOR). as well as symbols for literals (variables). For example, ‘a & b’, and (v0 | ~v1) & (~v2 & v3) are both valid string representation of boolean logical expressions.

For convenience, this oracle, in addition to parsing arbitrary logical expressions, also supports input strings in the DIMACS CNF format, which is the standard format for specifying SATisfiability (SAT) problem instances in Conjunctive Normal Form (CNF), which is a conjunction of one or more clauses, where a clause is a disjunction of one or more literals. See qiskit.circuit.library.phase_oracle.PhaseOracle.from_dimacs_file().

From 16 variables on, possible performance issues should be expected when using the default synthesizer.

Creates a PhaseOracle object

Parameters
• expression (Union[str, ClassicalElement]) – A Python-like boolean expression.

• synthesizer (Optional[Callable[[BooleanExpression], QuantumCircuit]]) – Optional. A function to convert a BooleanExpression into a QuantumCircuit If None is provided, Tweedledum’s pkrm_synth with phase_esop will be used.

Methods Defined Here

 evaluate_bitstring Evaluate the oracle on a bitstring. from_dimacs_file Create a PhaseOracle from the string in the DIMACS format.

Attributes

ancillas

Returns a list of ancilla bits in the order that the registers were added.

calibrations

Return calibration dictionary.

The custom pulse definition of a given gate is of the form

{‘gate_name’: {(qubits, params): schedule}}

clbits

Returns a list of classical bits in the order that the registers were added.

data

Return the circuit data (instructions and context).

Returns

a list-like object containing the tuples for the circuit’s data.

Each tuple is in the format (instruction, qargs, cargs), where instruction is an Instruction (or subclass) object, qargs is a list of Qubit objects, and cargs is a list of Clbit objects.

Return type

QuantumCircuitData

extension_lib = 'include "qelib1.inc";'
global_phase

Return the global phase of the circuit in radians.

header = 'OPENQASM 2.0;'
instances = 16
metadata

The user provided metadata associated with the circuit

The metadata for the circuit is a user provided dict of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.

num_ancillas

Return the number of ancilla qubits.

num_clbits

Return number of classical bits.

num_parameters

Convenience function to get the number of parameter objects in the circuit.

num_qubits

Return number of qubits.

parameters

Convenience function to get the parameters defined in the parameter table.

prefix = 'circuit'
qubits

Returns a list of quantum bits in the order that the registers were added.