# (C) Copyright IBM 2024.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""(Local) unitary cluster Jastrow ansatz gate."""
from __future__ import annotations
from collections.abc import Iterator, Sequence
from qiskit.circuit import (
CircuitInstruction,
Gate,
QuantumCircuit,
QuantumRegister,
Qubit,
)
from ffsim import variational
from ffsim.qiskit.gates.diag_coulomb import (
DiagCoulombEvolutionJW,
DiagCoulombEvolutionSpinlessJW,
)
from ffsim.qiskit.gates.orbital_rotation import (
OrbitalRotationJW,
OrbitalRotationSpinlessJW,
)
[docs]
class UCJOpSpinBalancedJW(Gate):
"""Spin-balanced UCJ operator under the Jordan-Wigner transformation.
See :class:`ffsim.UCJOpSpinBalanced` for a description of this gate's unitary.
This gate assumes that qubits are ordered such that the first ``norb`` qubits
correspond to the alpha orbitals and the last ``norb`` qubits correspond to the
beta orbitals.
"""
def __init__(
self,
ucj_op: variational.UCJOpSpinBalanced,
*,
tol: float = 1e-12,
orb_rot_max_givens: int | None = None,
orb_rot_max_layers: int | None = None,
label: str | None = None,
**optimize_kwargs,
):
"""Create a new spin-balanced unitary cluster Jastrow (UCJ) gate.
Args:
ucj_op: The UCJ operator.
tol: Tolerance for the Givens decomposition of the orbital rotations.
Matrix entries smaller than this value will be treated as equal to zero.
orb_rot_max_givens: The maximum number of Givens rotations to use for each
orbital rotation. If specified, the orbital rotation decompositions are
compressed to use at most this many Givens rotations, and the resulting
gate only approximates the UCJ operator. See
:func:`~ffsim.linalg.givens_decomposition` for details.
orb_rot_max_layers: The maximum number of brickwork layers to use for each
orbital rotation. If specified, the orbital rotation decompositions are
compressed to use at most this many layers, and the resulting gate only
approximates the UCJ operator. See
:func:`~ffsim.linalg.givens_decomposition` for details.
label: The label of the gate.
optimize_kwargs: Keyword arguments to pass to
:func:`scipy.optimize.minimize`, which performs the optimization when
the orbital rotation decompositions are compressed.
"""
self.ucj_op = ucj_op
self.tol = tol
self.orb_rot_max_givens = orb_rot_max_givens
self.orb_rot_max_layers = orb_rot_max_layers
self.optimize_kwargs = optimize_kwargs
super().__init__("ucj_balanced_jw", 2 * ucj_op.norb, [], label=label)
def _define(self):
"""Gate decomposition."""
qubits = QuantumRegister(self.num_qubits)
self.definition = QuantumCircuit.from_instructions(
_ucj_op_spin_balanced_jw(
qubits,
self.ucj_op,
tol=self.tol,
max_givens=self.orb_rot_max_givens,
max_layers=self.orb_rot_max_layers,
**self.optimize_kwargs,
),
qubits=qubits,
name=self.name,
)
def _ucj_op_spin_balanced_jw(
qubits: Sequence[Qubit],
ucj_op: variational.UCJOpSpinBalanced,
tol: float = 1e-12,
max_givens: int | None = None,
max_layers: int | None = None,
**optimize_kwargs,
) -> Iterator[CircuitInstruction]:
for (diag_coulomb_mat_aa, diag_coulomb_mat_ab), orbital_rotation in zip(
ucj_op.diag_coulomb_mats, ucj_op.orbital_rotations
):
yield CircuitInstruction(
OrbitalRotationJW(
ucj_op.norb,
orbital_rotation.T.conj(),
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
yield CircuitInstruction(
DiagCoulombEvolutionJW(
ucj_op.norb,
(diag_coulomb_mat_aa, diag_coulomb_mat_ab, diag_coulomb_mat_aa),
-1.0,
),
qubits,
)
yield CircuitInstruction(
OrbitalRotationJW(
ucj_op.norb,
orbital_rotation,
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
if ucj_op.final_orbital_rotation is not None:
yield CircuitInstruction(
OrbitalRotationJW(
ucj_op.norb,
ucj_op.final_orbital_rotation,
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
[docs]
class UCJOpSpinUnbalancedJW(Gate):
"""Spin-unbalanced UCJ operator under the Jordan-Wigner transformation.
See :class:`ffsim.UCJOpSpinUnbalanced` for a description of this gate's unitary.
This gate assumes that qubits are ordered such that the first ``norb`` qubits
correspond to the alpha orbitals and the last ``norb`` qubits correspond to the
beta orbitals.
"""
def __init__(
self,
ucj_op: variational.UCJOpSpinUnbalanced,
*,
tol: float = 1e-12,
orb_rot_max_givens: int | None = None,
orb_rot_max_layers: int | None = None,
label: str | None = None,
**optimize_kwargs,
):
"""Create a new spin-unbalanced unitary cluster Jastrow (UCJ) gate.
Args:
ucj_op: The UCJ operator.
tol: Tolerance for the Givens decomposition of the orbital rotations.
Matrix entries smaller than this value will be treated as equal to zero.
orb_rot_max_givens: The maximum number of Givens rotations to use for each
orbital rotation. If specified, the orbital rotation decompositions are
compressed to use at most this many Givens rotations, and the resulting
gate only approximates the UCJ operator. See
:func:`~ffsim.linalg.givens_decomposition` for details.
orb_rot_max_layers: The maximum number of brickwork layers to use for each
orbital rotation. If specified, the orbital rotation decompositions are
compressed to use at most this many layers, and the resulting gate only
approximates the UCJ operator. See
:func:`~ffsim.linalg.givens_decomposition` for details.
label: The label of the gate.
optimize_kwargs: Keyword arguments to pass to
:func:`scipy.optimize.minimize`, which performs the optimization when
the orbital rotation decompositions are compressed.
"""
self.ucj_op = ucj_op
self.tol = tol
self.orb_rot_max_givens = orb_rot_max_givens
self.orb_rot_max_layers = orb_rot_max_layers
self.optimize_kwargs = optimize_kwargs
super().__init__("ucj_unbalanced_jw", 2 * ucj_op.norb, [], label=label)
def _define(self):
"""Gate decomposition."""
qubits = QuantumRegister(self.num_qubits)
self.definition = QuantumCircuit.from_instructions(
_ucj_op_spin_unbalanced_jw(
qubits,
self.ucj_op,
tol=self.tol,
max_givens=self.orb_rot_max_givens,
max_layers=self.orb_rot_max_layers,
**self.optimize_kwargs,
),
qubits=qubits,
name=self.name,
)
def _ucj_op_spin_unbalanced_jw(
qubits: Sequence[Qubit],
ucj_op: variational.UCJOpSpinUnbalanced,
tol: float = 1e-12,
max_givens: int | None = None,
max_layers: int | None = None,
**optimize_kwargs,
) -> Iterator[CircuitInstruction]:
for diag_colomb_mat, orbital_rotation in zip(
ucj_op.diag_coulomb_mats, ucj_op.orbital_rotations
):
yield CircuitInstruction(
OrbitalRotationJW(
ucj_op.norb,
orbital_rotation.transpose(0, 2, 1).conj(),
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
yield CircuitInstruction(
DiagCoulombEvolutionJW(ucj_op.norb, diag_colomb_mat, -1.0),
qubits,
)
yield CircuitInstruction(
OrbitalRotationJW(
ucj_op.norb,
orbital_rotation,
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
if ucj_op.final_orbital_rotation is not None:
yield CircuitInstruction(
OrbitalRotationJW(
ucj_op.norb,
ucj_op.final_orbital_rotation,
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
[docs]
class UCJOpSpinlessJW(Gate):
"""Spinless UCJ operator under the Jordan-Wigner transformation.
See :class:`ffsim.UCJOpSpinless` for a description of this gate's unitary.
"""
def __init__(
self,
ucj_op: variational.UCJOpSpinless,
*,
tol: float = 1e-12,
orb_rot_max_givens: int | None = None,
orb_rot_max_layers: int | None = None,
label: str | None = None,
**optimize_kwargs,
):
"""Create a new spinless unitary cluster Jastrow (UCJ) gate.
Args:
ucj_op: The UCJ operator.
tol: Tolerance for the Givens decomposition of the orbital rotations.
Matrix entries smaller than this value will be treated as equal to zero.
orb_rot_max_givens: The maximum number of Givens rotations to use for each
orbital rotation. If specified, the orbital rotation decompositions are
compressed to use at most this many Givens rotations, and the resulting
gate only approximates the UCJ operator. See
:func:`~ffsim.linalg.givens_decomposition` for details.
orb_rot_max_layers: The maximum number of brickwork layers to use for each
orbital rotation. If specified, the orbital rotation decompositions are
compressed to use at most this many layers, and the resulting gate only
approximates the UCJ operator. See
:func:`~ffsim.linalg.givens_decomposition` for details.
label: The label of the gate.
optimize_kwargs: Keyword arguments to pass to
:func:`scipy.optimize.minimize`, which performs the optimization when
the orbital rotation decompositions are compressed.
"""
self.ucj_op = ucj_op
self.tol = tol
self.orb_rot_max_givens = orb_rot_max_givens
self.orb_rot_max_layers = orb_rot_max_layers
self.optimize_kwargs = optimize_kwargs
super().__init__("ucj_spinless_jw", ucj_op.norb, [], label=label)
def _define(self):
"""Gate decomposition."""
qubits = QuantumRegister(self.num_qubits)
self.definition = QuantumCircuit.from_instructions(
_ucj_op_spinless_jw(
qubits,
self.ucj_op,
tol=self.tol,
max_givens=self.orb_rot_max_givens,
max_layers=self.orb_rot_max_layers,
**self.optimize_kwargs,
),
qubits=qubits,
name=self.name,
)
def _ucj_op_spinless_jw(
qubits: Sequence[Qubit],
ucj_op: variational.UCJOpSpinless,
tol: float = 1e-12,
max_givens: int | None = None,
max_layers: int | None = None,
**optimize_kwargs,
) -> Iterator[CircuitInstruction]:
for diag_coulomb_mat, orbital_rotation in zip(
ucj_op.diag_coulomb_mats, ucj_op.orbital_rotations
):
yield CircuitInstruction(
OrbitalRotationSpinlessJW(
ucj_op.norb,
orbital_rotation.T.conj(),
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
yield CircuitInstruction(
DiagCoulombEvolutionSpinlessJW(ucj_op.norb, diag_coulomb_mat, -1.0),
qubits,
)
yield CircuitInstruction(
OrbitalRotationSpinlessJW(
ucj_op.norb,
orbital_rotation,
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)
if ucj_op.final_orbital_rotation is not None:
yield CircuitInstruction(
OrbitalRotationSpinlessJW(
ucj_op.norb,
ucj_op.final_orbital_rotation,
tol=tol,
max_givens=max_givens,
max_layers=max_layers,
**optimize_kwargs,
),
qubits,
)