def default_pass_manager(transpile_config):
"""
The default pass manager that maps to the coupling map.
Args:
transpile_config (TranspileConfig)
Returns:
PassManager: A pass manager to map and optimize.
"""
basis_gates = transpile_config.basis_gates
coupling_map = transpile_config.coupling_map
initial_layout = transpile_config.initial_layout
seed_transpiler = transpile_config.seed_transpiler
pass_manager = PassManager()
pass_manager.append(SetLayout(initial_layout))
pass_manager.append(Unroller(basis_gates))
# Use the trivial layout if no layout is found
pass_manager.append(
TrivialLayout(coupling_map),
condition=lambda property_set: not property_set['layout'])
# if the circuit and layout already satisfy the coupling_constraints, use that layout
# otherwise layout on the most densely connected physical qubit subset
pass_manager.append(CheckMap(coupling_map))
pass_manager.append(
DenseLayout(coupling_map),
condition=lambda property_set: not property_set['is_swap_mapped'])
# Extend the the dag/layout with ancillas using the full coupling map
pass_manager.append(FullAncillaAllocation(coupling_map))
pass_manager.append(EnlargeWithAncilla())
# Circuit must only contain 1- or 2-qubit interactions for swapper to work
pass_manager.append(Unroll3qOrMore())
# Swap mapper
pass_manager.append(BarrierBeforeFinalMeasurements())
pass_manager.append(
LegacySwap(coupling_map, trials=20, seed=seed_transpiler))
# Expand swaps
pass_manager.append(Decompose(SwapGate))
# Change CX directions
pass_manager.append(CXDirection(coupling_map))
# Simplify single qubit gates and CXs
simplification_passes = [
Optimize1qGates(),
CXCancellation(),
RemoveResetInZeroState()
]
pass_manager.append(
simplification_passes + [Depth(), FixedPoint('depth')],
do_while=lambda property_set: not property_set['depth_fixed_point'])
return pass_manager
def level_0_pass_manager(transpile_config):
"""
Level 0 pass manager: no explicit optimization other than mapping to backend.
This pass manager applies the user-given initial layout. If none is given, a trivial
layout consisting of mapping the i-th virtual qubit to the i-th physical qubit is used.
Any unused physical qubit is allocated as ancilla space.
The pass manager then unrolls the circuit to the desired basis, and transforms the
circuit to match the coupling map. Finally, extra resets are removed.
Note: in simulators where coupling_map=None, only the unrolling and optimization
stages are done.
Args:
transpile_config (TranspileConfig)
Returns:
PassManager: a level 0 pass manager.
"""
basis_gates = transpile_config.basis_gates
coupling_map = transpile_config.coupling_map
initial_layout = transpile_config.initial_layout
seed_transpiler = transpile_config.seed_transpiler
# 1. Use trivial layout if no layout given
_given_layout = SetLayout(initial_layout)
def _choose_layout_condition(property_set):
return not property_set['layout']
_choose_layout = TrivialLayout(coupling_map)
# 2. Extend dag/layout with ancillas using the full coupling map
_embed = [FullAncillaAllocation(coupling_map), EnlargeWithAncilla()]
# 3. Unroll to the basis
_unroll = Unroller(basis_gates)
# 4. Swap to fit the coupling map
_swap_check = CheckMap(coupling_map)
def _swap_condition(property_set):
return not property_set['is_swap_mapped']
_swap = [
BarrierBeforeFinalMeasurements(),
LegacySwap(coupling_map, trials=20, seed=seed_transpiler),
Decompose(SwapGate)
]
# 5. Fix any bad CX directions
# _direction_check = CheckCXDirection(coupling_map) # TODO
def _direction_condition(property_set):
return not property_set['is_direction_mapped']
_direction = [CXDirection(coupling_map)]
# 6. Remove zero-state reset
_reset = RemoveResetInZeroState()
pm0 = PassManager()
if coupling_map:
pm0.append(_given_layout)
pm0.append(_choose_layout, condition=_choose_layout_condition)
pm0.append(_embed)
pm0.append(_unroll)
if coupling_map:
pm0.append(_swap_check)
pm0.append(_swap, condition=_swap_condition)
# pm0.append(_direction_check) # TODO
pm0.append(_direction, condition=_direction_condition)
pm0.append(_reset)
return pm0
def level_1_pass_manager(transpile_config):
"""
Level 1 pass manager: light optimization by simple adjacent gate collapsing
This pass manager applies the user-given initial layout. If none is given, and a trivial
layout (i-th virtual -> i-th physical) makes the circuit fit the coupling map, that is used.
Otherwise, the circuit is mapped to the most densely connected coupling subgraph, and swaps
are inserted to map. Any unused physical qubit is allocated as ancilla space.
The pass manager then unrolls the circuit to the desired basis, and transforms the
circuit to match the coupling map. Finally, optimizations in the form of adjacent
gate collapse and redundant reset removal are performed.
Note: in simulators where coupling_map=None, only the unrolling and optimization
stages are done.
Args:
transpile_config (TranspileConfig)
Returns:
PassManager: a level 1 pass manager.
"""
basis_gates = transpile_config.basis_gates
coupling_map = transpile_config.coupling_map
initial_layout = transpile_config.initial_layout
seed_transpiler = transpile_config.seed_transpiler
# 1. Use trivial layout if no layout given
_given_layout = SetLayout(initial_layout)
def _choose_layout_condition(property_set):
return not property_set['layout']
_choose_layout = TrivialLayout(coupling_map)
# 2. Use a better layout on densely connected qubits, if circuit needs swaps
_layout_check = CheckMap(coupling_map)
def _improve_layout_condition(property_set):
return not property_set['is_swap_mapped']
_improve_layout = DenseLayout(coupling_map)
# 2. Extend dag/layout with ancillas using the full coupling map
_embed = [FullAncillaAllocation(coupling_map), EnlargeWithAncilla()]
# 3. Unroll to the basis
_unroll = Unroller(basis_gates)
# 4. Swap to fit the coupling map
_swap_check = CheckMap(coupling_map)
def _swap_condition(property_set):
return not property_set['is_swap_mapped']
_swap = [BarrierBeforeFinalMeasurements(),
LegacySwap(coupling_map, trials=20, seed=seed_transpiler),
Decompose(SwapGate)]
# 5. Fix any bad CX directions
# _direction_check = CheckCXDirection(coupling_map) # TODO
def _direction_condition(property_set):
return not property_set['is_direction_mapped']
_direction = [CXDirection(coupling_map)]
# 6. Remove zero-state reset
_reset = RemoveResetInZeroState()
# 7. Merge 1q rotations and cancel CNOT gates iteratively until no more change in depth
_depth_check = [Depth(), FixedPoint('depth')]
def _opt_control(property_set):
return not property_set['depth_fixed_point']
_opt = [Optimize1qGates(), CXCancellation()]
pm1 = PassManager()
if coupling_map:
pm1.append(_given_layout)
pm1.append(_choose_layout, condition=_choose_layout_condition)
pm1.append(_layout_check)
pm1.append(_improve_layout, condition=_improve_layout_condition)
pm1.append(_embed)
pm1.append(_unroll)
if coupling_map:
pm1.append(_swap_check)
pm1.append(_swap, condition=_swap_condition)
# pm1.append(_direction_check) # TODO
pm1.append(_direction, condition=_direction_condition)
pm1.append(_reset)
pm1.append(_depth_check + _opt, do_while=_opt_control)
return pm1
def level_3_pass_manager(transpile_config):
"""
Level 3 pass manager: heavy optimization by noise adaptive qubit mapping and
gate cancellation using commutativity rules and unitary synthesis.
This pass manager applies the user-given initial layout. If none is given, and
device calibration information is available, the circuit is mapped to the qubits
with best readouts and to CX gates with highest fidelity. Otherwise, a layout on
the most densely connected qubits is used.
The pass manager then transforms the circuit to match the coupling constraints.
It is then unrolled to the basis, and any flipped cx directions are fixed.
Finally, optimizations in the form of commutative gate cancellation, resynthesis
of two-qubit unitary blocks, and redundant reset removal are performed.
Note: in simulators where coupling_map=None, only the unrolling and optimization
stages are done.
Args:
transpile_config (TranspileConfig)
Returns:
PassManager: a level 3 pass manager.
"""
basis_gates = transpile_config.basis_gates
coupling_map = transpile_config.coupling_map
initial_layout = transpile_config.initial_layout
seed_transpiler = transpile_config.seed_transpiler
backend_properties = transpile_config.backend_properties
# 1. Layout on good qubits if calibration info available, otherwise on dense links
_given_layout = SetLayout(initial_layout)
def _choose_layout_condition(property_set):
return not property_set['layout']
_choose_layout = DenseLayout(coupling_map)
if backend_properties:
_choose_layout = NoiseAdaptiveLayout(backend_properties)
# 2. Extend dag/layout with ancillas using the full coupling map
_embed = [FullAncillaAllocation(coupling_map), EnlargeWithAncilla()]
# 3. Unroll to 1q or 2q gates, swap to fit the coupling map
_swap_check = CheckMap(coupling_map)
def _swap_condition(property_set):
return not property_set['is_swap_mapped']
_swap = [
BarrierBeforeFinalMeasurements(),
Unroll3qOrMore(),
LegacySwap(coupling_map, trials=20, seed=seed_transpiler)
]
# 4. Unroll to the basis
_unroll = Unroller(basis_gates)
# 5. 1q rotation merge and commutative cancellation iteratively until no more change in depth
_depth_check = [Depth(), FixedPoint('depth')]
def _opt_control(property_set):
return not property_set['depth_fixed_point']
_opt = [
RemoveResetInZeroState(),
Collect2qBlocks(),
ConsolidateBlocks(),
Unroller(basis_gates), # unroll unitaries
Optimize1qGates(),
CommutativeCancellation(),
OptimizeSwapBeforeMeasure(),
RemoveDiagonalGatesBeforeMeasure()
]
if coupling_map:
_opt.append(CXDirection(coupling_map))
# if a coupling map has been provided, match coupling
pm3 = PassManager()
if coupling_map:
pm3.append(_given_layout)
pm3.append(_choose_layout, condition=_choose_layout_condition)
pm3.append(_embed)
pm3.append(_unroll)
if coupling_map:
pm3.append(_swap_check)
pm3.append(_swap, condition=_swap_condition)
pm3.append(_depth_check + _opt, do_while=_opt_control)
return pm3
def level_2_pass_manager(transpile_config):
"""
Level 2 pass manager: medium optimization by noise adaptive qubit mapping and
gate cancellation using commutativity rules.
This pass manager applies the user-given initial layout. If none is given, and
device calibration information is available, the circuit is mapped to the qubits
with best readouts and to CX gates with highest fidelity. Otherwise, a layout on
the most densely connected qubits is used.
The pass manager then transforms the circuit to match the coupling constraints.
It is then unrolled to the basis, and any flipped cx directions are fixed.
Finally, optimizations in the form of commutative gate cancellation and redundant
reset removal are performed.
Note: in simulators where coupling_map=None, only the unrolling and optimization
stages are done.
Args:
transpile_config (TranspileConfig)
Returns:
PassManager: a level 2 pass manager.
"""
basis_gates = transpile_config.basis_gates
coupling_map = transpile_config.coupling_map
initial_layout = transpile_config.initial_layout
seed_transpiler = transpile_config.seed_transpiler
backend_properties = transpile_config.backend_properties
# 1. Layout on good qubits if calibration info available, otherwise on dense links
_given_layout = SetLayout(initial_layout)
def _choose_layout_condition(property_set):
return not property_set['layout']
_choose_layout = DenseLayout(coupling_map)
if backend_properties:
_choose_layout = NoiseAdaptiveLayout(backend_properties)
# 2. Extend dag/layout with ancillas using the full coupling map
_embed = [FullAncillaAllocation(coupling_map), EnlargeWithAncilla()]
# 3. Unroll to 1q or 2q gates, swap to fit the coupling map
_swap_check = CheckMap(coupling_map)
def _swap_condition(property_set):
return not property_set['is_swap_mapped']
_swap = [
BarrierBeforeFinalMeasurements(),
Unroll3qOrMore(),
LegacySwap(coupling_map),
Decompose(SwapGate)
]
# 4. Unroll to the basis
_unroll = Unroller(basis_gates)
# 5. Fix any bad CX directions
# _direction_check = CheckCXDirection(coupling_map) # TODO
def _direction_condition(property_set):
return not property_set['is_direction_mapped']
_direction = [CXDirection(coupling_map)]
# 6. Remove zero-state reset
_reset = RemoveResetInZeroState()
# 7. 1q rotation merge and commutative cancellation iteratively until no more change in depth
_depth_check = [Depth(), FixedPoint('depth')]
def _opt_control(property_set):
return not property_set['depth_fixed_point']
_opt = [Optimize1qGates(), CommutativeCancellation()]
pm2 = PassManager()
if coupling_map:
pm2.append(_given_layout)
pm2.append(_choose_layout, condition=_choose_layout_condition)
pm2.append(_embed)
pm2.append(_unroll)
if coupling_map:
pm2.append(_swap_check)
pm2.append(_swap, condition=_swap_condition)
# pm2.append(_direction_check) # TODO
pm2.append(_direction, condition=_direction_condition)
pm2.append(_reset)
pm2.append(_depth_check + _opt, do_while=_opt_control)
return pm2