QDrift
class qiskit.synthesis.QDrift(reps=1, insert_barriers=False, cx_structure='chain', atomic_evolution=None, seed=None, wrap=False)
Bases: ProductFormula
The QDrift Trotterization method, which selects each each term in the Trotterization randomly, with a probability proportional to its weight. Based on the work of Earl Campbell in Ref. [1].
References
[1]: E. Campbell, “A random compiler for fast Hamiltonian simulation” (2018). arXiv:quant-ph/1811.08017
The ‘Callable[[Pauli | SparsePauliOp, float], QuantumCircuit]’ signature of the ‘atomic_evolution’ argument is pending deprecation as of qiskit 1.2. It will be marked deprecated in a future release, and then removed no earlier than 3 months after the release date. Instead you should update your ‘atomic_evolution’ function to be of the following type: ‘Callable[[QuantumCircuit, Pauli | SparsePauliOp, float], None]’.
Parameters
- reps (int) – The number of times to repeat the Trotterization circuit.
- insert_barriers (bool) – Whether to insert barriers between the atomic evolutions.
- cx_structure (str) – How to arrange the CX gates for the Pauli evolutions, can be
"chain"
, where next neighbor connections are used, or"fountain"
, where all qubits are connected to one. This only takes effect whenatomic_evolution is None
. - atomic_evolution (Callable[[Pauli |SparsePauliOp, float], QuantumCircuit] | Callable[[QuantumCircuit, Pauli |SparsePauliOp, float], None] | None) – A function to apply the evolution of a single
Pauli
, orSparsePauliOp
of only commuting terms, to a circuit. The function takes in three arguments: the circuit to append the evolution to, the Pauli operator to evolve, and the evolution time. By default, a single Pauli evolution is decomposed into a chain ofCX
gates and a singleRZ
gate. Alternatively, the function can also take Pauli operator and evolution time as inputs and returns the circuit that will be appended to the overall circuit being built. - seed (int | None) – An optional seed for reproducibility of the random sampling process.
- wrap (bool) – Whether to wrap the atomic evolutions into custom gate objects. This only takes effect when
atomic_evolution is None
.
Attributes
settings
Return the settings in a dictionary, which can be used to reconstruct the object.
Returns
A dictionary containing the settings of this product formula.
Raises
NotImplementedError – If a custom atomic evolution is set, which cannot be serialized.
Methods
synthesize
synthesize(evolution)
Synthesize an qiskit.circuit.library.PauliEvolutionGate
.
Parameters
evolution (PauliEvolutionGate) – The evolution gate to synthesize.
Returns
A circuit implementing the evolution.
Return type