def test_path_qubits():
"""Source and target should be in the same line, otherwise ValueError should be returned."""
b = qb.CirqBoard(
u.squares_to_bitboard(['a1', 'b3', 'c4', 'd5', 'e6', 'f7']))
assert b.path_qubits("b3", "f7") == [bit_to_qubit(square_to_bit('c4')), \
bit_to_qubit(square_to_bit('d5')), \
bit_to_qubit(square_to_bit('e6'))]
with pytest.raises(ValueError):
b.path_qubits("a1", "b3")
with pytest.raises(ValueError):
b.path_qubits("c4", "a1")
def test_path_qubits():
"""Source and target should be in the same line, otherwise ValueError should be returned."""
b = qb.CirqBoard(
u.squares_to_bitboard(["a1", "b3", "c4", "d5", "e6", "f7"]))
assert b.path_qubits("b3", "f7") == [
bit_to_qubit(square_to_bit("c4")),
bit_to_qubit(square_to_bit("d5")),
bit_to_qubit(square_to_bit("e6")),
]
with pytest.raises(ValueError):
b.path_qubits("a1", "b3")
with pytest.raises(ValueError):
b.path_qubits("c4", "a1")
def path_qubits(self, source: str, target: str) -> List[cirq.Qid]:
"""Returns all entangled qubits (or classical pieces)
between source and target.
Source and target should be specified in algebraic notation,
such as 'f4'.
"""
rtn = []
xs = move.x_of(source)
ys = move.y_of(source)
xt = move.x_of(target)
yt = move.y_of(target)
if xt > xs:
dx = 1
elif xt < xs:
dx = -1
else:
dx = 0
if yt > ys:
dy = 1
elif yt < ys:
dy = -1
else:
dy = 0
max_slide = max(abs(xs - xt), abs(ys - yt))
if max_slide > 1:
for t in range(1, max_slide):
path_bit = xy_to_bit(xs + dx * t, ys + dy * t)
path_qubit = bit_to_qubit(path_bit)
if (path_qubit in self.entangled_squares
or nth_bit_of(path_bit, self.state)):
rtn.append(path_qubit)
return rtn
def path_qubits(self, source: str, target: str) -> List[cirq.Qid]:
"""Returns all entangled qubits (or classical pieces)
between source and target.
Source and target should be in the same line, i.e. same row,
same column, or same diagonal.
Source and target should be specified in algebraic notation,
such as 'f4'.
"""
rtn = []
xs = move.x_of(source)
ys = move.y_of(source)
xt = move.x_of(target)
yt = move.y_of(target)
if xt > xs:
dx = 1
elif xt < xs:
dx = -1
else:
dx = 0
if yt > ys:
dy = 1
elif yt < ys:
dy = -1
else:
dy = 0
x_slide = abs(xt - xs)
y_slide = abs(yt - ys)
# Souce and target should always be in the same line.
if x_slide != y_slide and x_slide * y_slide:
raise ValueError(
'Wrong inputs for path_qubits: source and target are not in the same line.'
)
max_slide = max(x_slide, y_slide)
# Only calculates path when max_slide > 1.
for t in range(1, max_slide):
path_bit = xy_to_bit(xs + dx * t, ys + dy * t)
path_qubit = bit_to_qubit(path_bit)
if (path_qubit in self.entangled_squares
or nth_bit_of(path_bit, self.state)):
rtn.append(path_qubit)
return rtn
def test_bit_to_qubit():
assert u.bit_to_qubit(2) == cirq.NamedQubit("2")
assert u.bit_to_qubit(0) == cirq.NamedQubit("0")
def test_bit_to_qubit():
assert u.bit_to_qubit(2) == cirq.NamedQubit("c1")
assert u.bit_to_qubit(63) == cirq.NamedQubit("h8")
def do_move(self, m: move.Move) -> int:
"""Performs a move on the quantum board.
Based on the type and variant of the move requested,
this function augments the circuit, classical registers,
and post-selection criteria to perform the board.
Returns: The measurement that was performed, or 1 if
no measurement was required.
"""
if not m.move_type:
raise ValueError('No Move defined')
if m.move_type == enums.MoveType.NULL_TYPE:
raise ValueError('Move has null type')
if m.move_type == enums.MoveType.UNSPECIFIED_STANDARD:
raise ValueError('Move type is unspecified')
# Reset accumulations here because function has conditional return branches
self.accumulations_repetitions = None
# Add move to the move move_history
self.move_history.append(m)
sbit = square_to_bit(m.source)
tbit = square_to_bit(m.target)
squbit = bit_to_qubit(sbit)
tqubit = bit_to_qubit(tbit)
if (m.move_variant == enums.MoveVariant.CAPTURE
or m.move_type == enums.MoveType.PAWN_EP
or m.move_type == enums.MoveType.PAWN_CAPTURE):
# TODO: figure out if it is a deterministic capture.
for val in list(self.allowed_pieces):
self.allowed_pieces.add(val - 1)
if m.move_type == enums.MoveType.PAWN_EP:
# For en passant, first determine the square of the pawn being
# captured, which should be next to the target.
if m.target[1] == '6':
epbit = square_to_bit(m.target[0] + '5')
elif m.target[1] == '2':
epbit = square_to_bit(m.target[0] + '4')
else:
raise ValueError(f'Invalid en passant target {m.target}')
epqubit = bit_to_qubit(epbit)
# For the classical version, set the bits appropriately
if (epqubit not in self.entangled_squares
and squbit not in self.entangled_squares
and tqubit not in self.entangled_squares):
if (not nth_bit_of(epbit, self.state)
or not nth_bit_of(sbit, self.state)
or nth_bit_of(tbit, self.state)):
raise ValueError('Invalid classical e.p. move')
self.state = set_nth_bit(epbit, self.state, False)
self.state = set_nth_bit(sbit, self.state, False)
self.state = set_nth_bit(tbit, self.state, True)
return 1
# If any squares are quantum, it's a quantum move
self.add_entangled(squbit, tqubit, epqubit)
# Capture e.p. post-select on the source
if m.move_variant == enums.MoveVariant.CAPTURE:
is_there = self.post_select_on(squbit)
if not is_there:
return 0
self.add_entangled(squbit)
path_ancilla = self.new_ancilla()
captured_ancilla = self.new_ancilla()
captured_ancilla2 = self.new_ancilla()
# capture e.p. has a special circuit
self.circuit.append(
qm.capture_ep(squbit, tqubit, epqubit, self.new_ancilla(),
self.new_ancilla(), self.new_ancilla()))
return 1
# Blocked/excluded e.p. post-select on the target
if m.move_variant == enums.MoveVariant.EXCLUDED:
is_there = self.post_select_on(tqubit)
if is_there:
return 0
self.add_entangled(tqubit)
self.circuit.append(
qm.en_passant(squbit, tqubit, epqubit, self.new_ancilla(),
self.new_ancilla()))
return 1
if m.move_type == enums.MoveType.PAWN_CAPTURE:
# For pawn capture, first measure source.
is_there = self.post_select_on(squbit)
if not is_there:
return 0
if tqubit in self.entangled_squares:
old_tqubit = self.unhook(tqubit)
self.add_entangled(squbit, tqubit)
self.circuit.append(
qm.controlled_operation(cirq.ISWAP, [squbit, tqubit],
[old_tqubit], []))
else:
# Classical case
self.state = set_nth_bit(sbit, self.state, False)
self.state = set_nth_bit(tbit, self.state, True)
return 1
if m.move_type == enums.MoveType.SPLIT_SLIDE:
tbit2 = square_to_bit(m.target2)
tqubit2 = bit_to_qubit(tbit2)
# Find all the squares on both paths
path_qubits = self.path_qubits(m.source, m.target)
path_qubits2 = self.path_qubits(m.source, m.target2)
if len(path_qubits) == 0 and len(path_qubits2) == 0:
# No interposing squares, just jump.
m.move_type = enums.MoveType.SPLIT_JUMP
else:
self.add_entangled(squbit, tqubit, tqubit2)
path1 = self.create_path_ancilla(path_qubits)
path2 = self.create_path_ancilla(path_qubits2)
ancilla = self.new_ancilla()
self.circuit.append(
qm.split_slide(squbit, tqubit, tqubit2, path1, path2,
ancilla))
return 1
if m.move_type == enums.MoveType.MERGE_SLIDE:
sbit2 = square_to_bit(m.source2)
squbit2 = bit_to_qubit(sbit2)
self.add_entangled(squbit, squbit2, tqubit)
# Find all the squares on both paths
path_qubits = self.path_qubits(m.source, m.target)
path_qubits2 = self.path_qubits(m.source2, m.target)
if len(path_qubits) == 0 and len(path_qubits2) == 0:
# No interposing squares, just jump.
m.move_type = enums.MoveType.MERGE_JUMP
else:
path1 = self.create_path_ancilla(path_qubits)
path2 = self.create_path_ancilla(path_qubits2)
ancilla = self.new_ancilla()
self.circuit.append(
qm.merge_slide(squbit, tqubit, squbit2, path1, path2,
ancilla))
return 1
if (m.move_type == enums.MoveType.SLIDE
or m.move_type == enums.MoveType.PAWN_TWO_STEP):
path_qubits = self.path_qubits(m.source, m.target)
if len(path_qubits) == 0:
# No path, change to jump
m.move_type = enums.MoveType.JUMP
if (m.move_type == enums.MoveType.SLIDE
or m.move_type == enums.MoveType.PAWN_TWO_STEP):
for p in path_qubits:
if (p not in self.entangled_squares
and nth_bit_of(qubit_to_bit(p), self.state)):
# Classical piece in the way
return 0
# For excluded case, measure target
if m.move_variant == enums.MoveVariant.EXCLUDED:
is_there = self.post_select_on(tqubit)
if is_there:
return 0
self.add_entangled(squbit, tqubit)
if m.move_variant == enums.MoveVariant.CAPTURE:
capture_ancilla = self.new_ancilla()
self.circuit.append(
qm.controlled_operation(cirq.X, [capture_ancilla],
[squbit], path_qubits))
# We need to add the captured_ancilla to entangled squares
# So that we measure it
self.entangled_squares.add(capture_ancilla)
capture_allowed = self.post_select_on(capture_ancilla)
if not capture_allowed:
return 0
else:
# Perform the captured slide
self.add_entangled(squbit)
# Remove the target from the board into an ancilla
# and set bit to zero
self.unhook(tqubit)
self.state = set_nth_bit(tbit, self.state, False)
# Re-add target since we need to swap into the square
self.add_entangled(tqubit)
# Perform the actual move
self.circuit.append(qm.normal_move(squbit, tqubit))
# Set source to empty
self.unhook(squbit)
self.state = set_nth_bit(sbit, self.state, False)
# Now set the whole path to empty
for p in path_qubits:
self.state = set_nth_bit(qubit_to_bit(p), self.state,
False)
self.unhook(p)
return 1
# Basic slide (or successful excluded slide)
# Add all involved squares into entanglement
self.add_entangled(squbit, tqubit, *path_qubits)
if len(path_qubits) == 1:
# For path of one, no ancilla needed
self.circuit.append(qm.slide_move(squbit, tqubit, path_qubits))
return 1
# Longer paths require a path ancilla
ancilla = self.new_ancilla()
self.circuit.append(
qm.slide_move(squbit, tqubit, path_qubits, ancilla))
return 1
if (m.move_type == enums.MoveType.JUMP
or m.move_type == enums.MoveType.PAWN_STEP):
if (squbit not in self.entangled_squares
and tqubit not in self.entangled_squares):
# Classical version
self.state = set_nth_bit(sbit, self.state, False)
self.state = set_nth_bit(tbit, self.state, True)
return 1
# Measure source for capture
if m.move_variant == enums.MoveVariant.CAPTURE:
is_there = self.post_select_on(squbit)
if not is_there:
return 0
self.unhook(tqubit)
# Measure target for excluded
if m.move_variant == enums.MoveVariant.EXCLUDED:
is_there = self.post_select_on(tqubit)
if is_there:
return 0
# Only convert source qubit to ancilla if target
# is empty
unhook = tqubit not in self.entangled_squares
self.add_entangled(squbit, tqubit)
# Execute jump
self.circuit.append(qm.normal_move(squbit, tqubit))
if unhook or m.move_variant != enums.MoveVariant.BASIC:
# The source is empty.
# Change source qubit to be an ancilla
# and set classical bit to zero
self.state = set_nth_bit(sbit, self.state, False)
self.unhook(squbit)
return 1
if m.move_type == enums.MoveType.SPLIT_JUMP:
tbit2 = square_to_bit(m.target2)
tqubit2 = bit_to_qubit(tbit2)
self.add_entangled(squbit, tqubit, tqubit2)
self.circuit.append(qm.split_move(squbit, tqubit, tqubit2))
self.state = set_nth_bit(sbit, self.state, False)
self.unhook(squbit)
return 1
if m.move_type == enums.MoveType.MERGE_JUMP:
sbit2 = square_to_bit(m.source2)
squbit2 = bit_to_qubit(sbit2)
self.add_entangled(squbit, squbit2, tqubit)
self.circuit.append(qm.merge_move(squbit, squbit2, tqubit))
# TODO: should the source qubit be 'unhooked'?
return 1
if m.move_type == enums.MoveType.KS_CASTLE:
# Figure out the rook squares
if sbit == square_to_bit('e1') and tbit == square_to_bit('g1'):
rook_sbit = square_to_bit('h1')
rook_tbit = square_to_bit('f1')
elif sbit == square_to_bit('e8') and tbit == square_to_bit('g8'):
rook_sbit = square_to_bit('h8')
rook_tbit = square_to_bit('f8')
else:
raise ValueError(f'Invalid kingside castling move')
rook_squbit = bit_to_qubit(rook_sbit)
rook_tqubit = bit_to_qubit(rook_tbit)
# Piece in non-superposition in the way, not legal
if (nth_bit_of(rook_tbit, self.state)
and rook_tqubit not in self.entangled_squares):
return 0
if (nth_bit_of(tbit, self.state)
and tqubit not in self.entangled_squares):
return 0
# Not in superposition, just castle
if (rook_tqubit not in self.entangled_squares
and tqubit not in self.entangled_squares):
self.set_castle(sbit, rook_sbit, tbit, rook_tbit)
return 1
# Both intervening squares in superposition
if (rook_tqubit in self.entangled_squares
and tqubit in self.entangled_squares):
castle_ancilla = self.create_path_ancilla(
[rook_tqubit, tqubit])
self.entangled_squares.add(castle_ancilla)
castle_allowed = self.post_select_on(castle_ancilla)
if castle_allowed:
self.unhook(rook_tqubit)
self.unhook(tqubit)
self.set_castle(sbit, rook_sbit, tbit, rook_tbit)
return 1
else:
self.post_selection[castle_ancilla] = castle_allowed
return 0
# One intervening square in superposition
if rook_tqubit in self.entangled_squares:
measure_qubit = rook_tqubit
measure_bit = rook_tbit
else:
measure_qubit = tqubit
measure_bit = tbit
is_there = self.post_select_on(measure_qubit)
if is_there:
return 0
self.set_castle(sbit, rook_sbit, tbit, rook_tbit)
return 1
if m.move_type == enums.MoveType.QS_CASTLE:
# Figure out the rook squares and the b-file square involved
if sbit == square_to_bit('e1') and tbit == square_to_bit('c1'):
rook_sbit = square_to_bit('a1')
rook_tbit = square_to_bit('d1')
b_bit = square_to_bit('b1')
elif sbit == square_to_bit('e8') and tbit == square_to_bit('c8'):
rook_sbit = square_to_bit('a8')
rook_tbit = square_to_bit('d8')
b_bit = square_to_bit('b8')
else:
raise ValueError(f'Invalid queenside castling move')
rook_squbit = bit_to_qubit(rook_sbit)
rook_tqubit = bit_to_qubit(rook_tbit)
b_qubit = bit_to_qubit(b_bit)
# Piece in non-superposition in the way, not legal
if (nth_bit_of(rook_tbit, self.state)
and rook_tqubit not in self.entangled_squares):
return 0
if (nth_bit_of(tbit, self.state)
and tqubit not in self.entangled_squares):
return 0
if (b_bit is not None and nth_bit_of(b_bit, self.state)
and b_qubit not in self.entangled_squares):
return 0
# Not in superposition, just castle
if (rook_tqubit not in self.entangled_squares
and tqubit not in self.entangled_squares
and b_qubit not in self.entangled_squares):
self.set_castle(sbit, rook_sbit, tbit, rook_tbit)
return 1
# Neither intervening squares in superposition
if (rook_tqubit not in self.entangled_squares
and tqubit not in self.entangled_squares):
if b_qubit not in self.entangled_squares:
self.set_castle(sbit, rook_sbit, tbit, rook_tbit)
else:
self.queenside_castle(squbit, rook_squbit, tqubit,
rook_tqubit, b_qubit)
return 1
# Both intervening squares in superposition
if (rook_tqubit in self.entangled_squares
and tqubit in self.entangled_squares):
castle_ancilla = self.create_path_ancilla(
[rook_tqubit, tqubit])
self.entangled_squares.add(castle_ancilla)
castle_allowed = self.post_select_on(castle_ancilla)
if castle_allowed:
self.unhook(rook_tqubit)
self.unhook(tqubit)
if b_qubit not in self.entangled_squares:
self.set_castle(sbit, rook_sbit, tbit, rook_tbit)
else:
self.queenside_castle(squbit, rook_squbit, tqubit,
rook_tqubit, b_qubit)
return 1
else:
self.post_selection[castle_ancilla] = castle_allowed
return 0
# One intervening square in superposition
if rook_tqubit in self.entangled_squares:
measure_qubit = rook_tqubit
measure_bit = rook_tbit
else:
measure_qubit = tqubit
measure_bit = tbit
is_there = self.post_select_on(measure_qubit)
if is_there:
return 0
if b_qubit not in self.entangled_squares:
self.set_castle(sbit, rook_sbit, tbit, rook_tbit)
else:
self.queenside_castle(squbit, rook_squbit, tqubit, rook_tqubit,
b_qubit)
return 1
raise ValueError(f'Move type {m.move_type} not supported')
