def add_bit(self, unit, offset=None):
""" Add a bit, update post_processing. """
if offset is not None:
self.post_processing @= Id(bit)
self.post_processing >>= Id(bit ** offset)\
@ Id.swap(self.post_processing.cod[offset:-1], bit)
super().add_bit(unit)
def random_tiling(n_qubits, depth=3, gateset=None, seed=None):
""" Returns a random Euler decomposition if n_qubits == 1,
otherwise returns a random tiling with the given depth and gateset.
>>> c = random_tiling(1, seed=420)
>>> print(c)
Rx(0.0263) >> Rz(0.781) >> Rx(0.273)
>>> print(random_tiling(2, 2, gateset=[CX, H, T], seed=420))
CX >> T @ Id(1) >> Id(1) @ T
>>> print(random_tiling(3, 2, gateset=[CX, H, T], seed=420))
CX @ Id(1) >> Id(2) @ T >> H @ Id(2) >> Id(1) @ H @ Id(1) >> Id(2) @ H
>>> print(random_tiling(2, 1, gateset=[Rz, Rx], seed=420))
Rz(0.673) @ Id(1) >> Id(1) @ Rx(0.273)
"""
gateset = gateset or [H, Rx, CX]
if seed is not None:
random.seed(seed)
if n_qubits == 1:
phases = [random.random() for _ in range(3)]
return Rx(phases[0]) >> Rz(phases[1]) >> Rx(phases[2])
result = Id(n_qubits)
for _ in range(depth):
line, n_affected = Id(0), 0
while n_affected < n_qubits:
gate = random.choice(
gateset if n_qubits - n_affected > 1 else
[g for g in gateset if g is Rx or g is Rz or len(g.dom) == 1])
if gate is Rx or gate is Rz:
gate = gate(random.random())
line = line @ gate
n_affected += len(gate.dom)
result = result >> line
return result
def make_units_adjacent(tk_gate):
offset = tk_gate.qubits[0].index[0]
swaps = Id(qubit**n_qubits @ bit**n_bits)
for i, tk_qubit in enumerate(tk_gate.qubits[1:]):
source, target = tk_qubit.index[0], offset + i + 1
if source < target:
left, right = swaps.cod[:source], swaps.cod[target:]
swap = Id.swap(swaps.cod[source:source + 1],
swaps.cod[source + 1:target])
if source <= offset:
offset -= 1
elif source > target:
left, right = swaps.cod[:target], swaps.cod[source + 1:]
swap = Id.swap(swaps.cod[target:target + 1],
swaps.cod[target + 1:source + 1])
else: # pragma: no cover
continue # units are adjacent already
swaps = swaps >> Id(left) @ swap @ Id(right)
return offset, swaps
def __init__(self,
n_qubits=0,
n_bits=0,
post_selection=None,
scalar=None,
post_processing=None):
self.post_selection = post_selection or {}
self.scalar = scalar or 1
self.post_processing = post_processing\
or Id(bit ** (n_bits - len(self.post_selection)))
super().__init__(n_qubits, n_bits)
def grad(self, var, **params):
if var not in self.free_symbols:
return Sum([], self.dom, self.cod)
if params.get('mixed', True):
return super().grad(var, **params)
gradient = self.phase.diff(var)
gradient = complex(gradient) if not gradient.free_symbols else gradient
_i_half_pi = .5j * self.modules.pi
op1 = Z @ X @ scalar(_i_half_pi * gradient)
op2 = Id(qubit) @ X @ scalar(-_i_half_pi * gradient)
return self >> (op1 + op2)
def __init__(self, n_qubits, params):
def layer(thetas):
hadamards = Id(0).tensor(*(n_qubits * [H]))
rotations = Id(n_qubits).then(
*(Id(i) @ CRz(thetas[i]) @ Id(n_qubits - 2 - i)
for i in range(n_qubits - 1)))
return hadamards >> rotations
if n_qubits == 1:
circuit = Rx(params[0]) >> Rz(params[1]) >> Rx(params[2])
elif len(np.shape(params)) != 2 or np.shape(params)[1] != n_qubits - 1:
raise ValueError(
"Expected params of shape (depth, {})".format(n_qubits - 1))
else:
depth = np.shape(params)[0]
circuit = Id(n_qubits).then(*(layer(params[i])
for i in range(depth)))
super().__init__(circuit.dom, circuit.cod, circuit.boxes,
circuit.offsets)
def from_tk(tk_circuit):
"""
Translates from tket to discopy.
"""
if not isinstance(tk_circuit, tk.Circuit):
raise TypeError(messages.type_err(tk.Circuit, tk_circuit))
if not isinstance(tk_circuit, Circuit):
tk_circuit = Circuit.upgrade(tk_circuit)
n_bits = tk_circuit.n_bits - len(tk_circuit.post_selection)
n_qubits = tk_circuit.n_qubits
def box_from_tk(tk_gate):
name = tk_gate.op.type.name
if name == 'Rx':
return Rx(tk_gate.op.params[0] / 2)
if name == 'Rz':
return Rz(tk_gate.op.params[0] / 2)
if name == 'CRz':
return CRz(tk_gate.op.params[0] / 2)
for gate in GATES:
if name == gate.name:
return gate
raise NotImplementedError
def make_units_adjacent(tk_gate):
offset = tk_gate.qubits[0].index[0]
swaps = Id(qubit**n_qubits @ bit**n_bits)
for i, tk_qubit in enumerate(tk_gate.qubits[1:]):
source, target = tk_qubit.index[0], offset + i + 1
if source < target:
left, right = swaps.cod[:source], swaps.cod[target:]
swap = Id.swap(swaps.cod[source:source + 1],
swaps.cod[source + 1:target])
if source <= offset:
offset -= 1
elif source > target:
left, right = swaps.cod[:target], swaps.cod[source + 1:]
swap = Id.swap(swaps.cod[target:target + 1],
swaps.cod[target + 1:source + 1])
else: # pragma: no cover
continue # units are adjacent already
swaps = swaps >> Id(left) @ swap @ Id(right)
return offset, swaps
circuit = Id(0).tensor(*(n_qubits * [Ket(0)] + n_bits * [Bits(0)]))
bras = {}
for tk_gate in tk_circuit.get_commands():
if tk_gate.op.type.name == "Measure":
offset = tk_gate.qubits[0].index[0]
bit_index = tk_gate.bits[0].index[0]
if bit_index in tk_circuit.post_selection:
bras[offset] = tk_circuit.post_selection[bit_index]
continue # post selection happens at the end
box = Measure(destructive=False, override_bits=True)
swaps = Id(circuit.cod[:offset + 1])
swaps = swaps @ Id.swap(
circuit.cod[offset + 1:n_qubits + bit_index],
circuit.cod[n_qubits:][bit_index: bit_index + 1])\
@ Id(circuit.cod[n_qubits + bit_index + 1:])
else:
box = box_from_tk(tk_gate)
offset, swaps = make_units_adjacent(tk_gate)
left, right = swaps.cod[:offset], swaps.cod[offset + len(box.dom):]
circuit = circuit >> swaps >> Id(left) @ box @ Id(right) >> swaps[::-1]
circuit = circuit >> Id(0).tensor(*(Bra(bras[i]) if i in bras else Discard(
) if x.name == 'qubit' else Id(bit) for i, x in enumerate(circuit.cod)))
if tk_circuit.scalar != 1:
circuit = circuit @ MixedScalar(tk_circuit.scalar)
return circuit >> tk_circuit.post_processing
def remove_ket1(box):
if not isinstance(box, Ket):
return box
x_gates = Id(0).tensor(*(X if x else Id(1) for x in box.bitstring))
return Ket(*(len(box.bitstring) * (0, ))) >> x_gates
def to_tk(circuit):
"""
Takes a :class:`discopy.quantum.Circuit`, returns a :class:`Circuit`.
"""
# bits and qubits are lists of register indices, at layer i we want
# len(bits) == circuit[:i].cod.count(bit) and same for qubits
tk_circ, bits, qubits = Circuit(), [], []
circuit = circuit.init_and_discard()
def remove_ket1(box):
if not isinstance(box, Ket):
return box
x_gates = Id(0).tensor(*(X if x else Id(1) for x in box.bitstring))
return Ket(*(len(box.bitstring) * (0, ))) >> x_gates
def prepare_qubits(qubits, box, offset):
renaming = dict()
start = tk_circ.n_qubits if not qubits else 0\
if not offset else qubits[offset - 1] + 1
for i in range(start, tk_circ.n_qubits):
old = Qubit('q', i)
new = Qubit('q', i + len(box.cod))
renaming.update({old: new})
tk_circ.rename_units(renaming)
tk_circ.add_blank_wires(len(box.cod))
return qubits[:offset] + list(range(start, start + len(box.cod)))\
+ [i + len(box.cod) for i in qubits[offset:]]
def prepare_bits(bits, box, offset):
renaming = dict()
start = tk_circ.n_bits if not bits else 0\
if not offset else bits[offset - 1] + 1
for i in range(start, tk_circ.n_bits):
old = Bit(i)
new = Bit(i + len(box.cod))
renaming.update({old: new})
tk_circ.rename_units(renaming)
for i in range(start, start + len(box.cod)):
tk_circ.add_bit(Bit(i), offset=offset + i - start)
return bits[:offset] + list(range(start, start + len(box.cod)))\
+ [i + len(box.cod) for i in bits[offset:]]
def measure_qubits(qubits, bits, box, bit_offset, qubit_offset):
if isinstance(box, Measure) and box.override_bits:
for j, _ in enumerate(box.dom[:len(box.dom) // 2]):
i_bit = bits[bit_offset + j]
i_qubit = qubits[qubit_offset + j]
tk_circ.Measure(i_qubit, i_bit)
return bits, qubits
for j, _ in enumerate(box.dom):
i_bit, i_qubit = len(tk_circ.bits), qubits[qubit_offset + j]
offset = len(bits) if isinstance(box, Measure) else None
tk_circ.add_bit(Bit(i_bit), offset=offset)
tk_circ.Measure(i_qubit, i_bit)
if isinstance(box, Bra):
tk_circ.post_select({i_bit: box.bitstring[j]})
if isinstance(box, Measure):
bits = bits[:bit_offset + j] + [i_bit] + bits[bit_offset + j:]
if isinstance(box, Bra)\
or isinstance(box, Measure) and box.destructive:
qubits = qubits[:qubit_offset]\
+ qubits[qubit_offset + len(box.dom):]
return bits, qubits
def swap(i, j, unit_factory=Qubit):
old, tmp, new =\
unit_factory(i), unit_factory('tmp', 0), unit_factory(j)
tk_circ.rename_units({old: tmp})
tk_circ.rename_units({new: old})
tk_circ.rename_units({tmp: new})
def add_gate(qubits, box, offset):
i_qubits = [qubits[offset + j] for j in range(len(box.dom))]
if isinstance(box, (Rx, Rz)):
tk_circ.__getattribute__(box.name[:2])(2 * box.phase, *i_qubits)
elif isinstance(box, CRz):
tk_circ.__getattribute__(box.name[:3])(2 * box.phase, *i_qubits)
elif hasattr(tk_circ, box.name):
tk_circ.__getattribute__(box.name)(*i_qubits)
else:
raise NotImplementedError
circuit = Functor(ob=lambda x: x, ar=remove_ket1)(circuit)
for left, box, _ in circuit.layers:
if isinstance(box, Ket):
qubits = prepare_qubits(qubits, box, left.count(qubit))
elif isinstance(box, Bits) and not box.is_dagger:
if 1 in box.bitstring:
raise NotImplementedError
bits = prepare_bits(bits, box, left.count(bit))
elif isinstance(box, (Measure, Bra)):
bits, qubits = measure_qubits(qubits, bits, box, left.count(bit),
left.count(qubit))
elif isinstance(box, Discard):
bits = bits[:left.count(bit)]\
+ bits[left.count(bit) + box.dom.count(bit):]
qubits = qubits[:left.count(qubit)]\
+ qubits[left.count(qubit) + box.dom.count(qubit):]
elif isinstance(box, Swap):
if box == Swap(qubit, qubit):
off = left.count(qubit)
swap(qubits[off], qubits[off + 1])
elif box == Swap(bit, bit):
off = left.count(bit)
if tk_circ.post_processing:
right = Id(tk_circ.post_processing.cod[off + 2:])
tk_circ.post_process(Id(bit**off) @ Swap(bit, bit) @ right)
else:
swap(bits[off], bits[off + 1], unit_factory=Bit)
else: # pragma: no cover
continue # bits and qubits live in different registers.
elif isinstance(box, Scalar):
tk_circ.scale(
box.array[0] if box.is_mixed else abs(box.array[0])**2)
elif isinstance(box, ClassicalGate)\
or isinstance(box, Bits) and box.is_dagger:
off = left.count(bit)
right = Id(tk_circ.post_processing.cod[off + len(box.dom):])
tk_circ.post_process(Id(bit**off) @ box @ right)
elif isinstance(box, QuantumGate):
add_gate(qubits, box, left.count(qubit))
else: # pragma: no cover
raise NotImplementedError
return tk_circ
def layer(thetas):
hadamards = Id(0).tensor(*(n_qubits * [H]))
rotations = Id(n_qubits).then(
*(Id(i) @ CRz(thetas[i]) @ Id(n_qubits - 2 - i)
for i in range(n_qubits - 1)))
return hadamards >> rotations
