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add generaldepolarizingchannel
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+164
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‎tensorcircuit/channels.py

+136-5
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,9 @@
33
"""
44

55
import sys
6-
from typing import Any, Sequence
6+
from typing import Any, Sequence, Optional, Union
7+
from operator import and_
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from functools import reduce
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import numpy as np
911

@@ -78,6 +80,128 @@ def depolarizingchannel(px: float, py: float, pz: float) -> Sequence[Gate]:
7880
return [i, x, y, z]
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8082

83+
def generaldepolarizingchannel(
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p: Union[float, Sequence[Any]], num_qubits: int = 1
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) -> Sequence[Gate]:
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"""Return a Depolarizing Channel
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.. math::
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\sqrt{1-p_x-p_y-p_z}
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\begin{bmatrix}
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1 & 0\\
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0 & 1\\
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\end{bmatrix}\qquad
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\sqrt{p_x}
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\begin{bmatrix}
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0 & 1\\
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1 & 0\\
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\end{bmatrix}\qquad
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\sqrt{p_y}
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\begin{bmatrix}
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0 & -1j\\
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1j & 0\\
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\end{bmatrix}\qquad
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\sqrt{p_z}
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\begin{bmatrix}
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1 & 0\\
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0 & -1\\
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\end{bmatrix}
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:Example:
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>>> cs=tc.channels.generaldepolarizingchannel([0.1,0.1,0.1],1)
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>>> tc.channels.kraus_identity_check(cs)
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>>> cs = tc.channels.generaldepolarizingchannel(0.02,2)
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>>> tc.channels.kraus_identity_check(cs)
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:param p: parameter for each Pauli channel
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:type p: Union[float, Sequence]
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:param num_qubits: number of qubits, defaults to 1
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:type num_qubits: int, optional
122+
:return: Sequences of Gates
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:rtype: Sequence[Gate]
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"""
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if num_qubits == 1:
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if isinstance(p, float):
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assert p > 0 and p < 1 / 3, "p should be >0 and <1/3"
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probs = [1 - 3 * p] + 3 * [p]
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elif isinstance(p, list):
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assert reduce(
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and_, [pi > 0 and pi < 1 for pi in p]
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), "p should be >0 and <1"
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probs = [1 - sum(p)] + p # type: ignore
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elif isinstance(p, tuple):
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p = list[p] # type: ignore
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assert reduce(
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and_, [pi > 0 and pi < 1 for pi in p]
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), "p should be >0 and <1"
146+
probs = [1 - sum(p)] + p # type: ignore
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else:
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raise ValueError("p should be float or list")
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elif num_qubits == 2:
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if isinstance(p, float):
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assert p > 0 and p < 1, "p should be >0 and <1/15"
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probs = [1 - 15 * p] + 15 * [p]
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elif isinstance(p, list):
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assert reduce(
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and_, [pi > 0 and pi < 1 for pi in p]
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), "p should be >0 and <1"
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probs = [1 - sum(p)] + p # type: ignore
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elif isinstance(p, tuple):
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p = list[p] # type: ignore
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assert reduce(
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and_, [pi > 0 and pi < 1 for pi in p]
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), "p should be >0 and <1"
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probs = [1 - sum(p)] + p # type: ignore
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else:
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raise ValueError("p should be float or list")
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if num_qubits == 1:
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tup = [gates.i().tensor, gates.x().tensor, gates.y().tensor, gates.z().tensor] # type: ignore
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if num_qubits == 2:
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tup = [
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gates.ii().tensor, # type: ignore
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gates.ix().tensor, # type: ignore
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gates.iy().tensor, # type: ignore
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gates.iz().tensor, # type: ignore
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gates.xi().tensor, # type: ignore
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gates.xx().tensor, # type: ignore
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gates.xy().tensor, # type: ignore
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gates.xz().tensor, # type: ignore
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gates.yi().tensor, # type: ignore
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gates.yx().tensor, # type: ignore
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gates.yy().tensor, # type: ignore
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gates.yz().tensor, # type: ignore
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gates.zi().tensor, # type: ignore
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gates.zx().tensor, # type: ignore
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gates.zy().tensor, # type: ignore
195+
gates.zz().tensor, # type: ignore
196+
]
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198+
Gkarus = []
199+
for pro, paugate in zip(probs, tup):
200+
Gkarus.append(Gate(_sqrt(pro) * paugate))
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return Gkarus
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204+
81205
def amplitudedampingchannel(gamma: float, p: float) -> Sequence[Gate]:
82206
r"""
83207
Return an amplitude damping channel.
@@ -187,25 +311,32 @@ def phasedampingchannel(gamma: float) -> Sequence[Gate]:
187311
return [m0, m1]
188312

189313

190-
def single_qubit_kraus_identity_check(kraus: Sequence[Gate]) -> None:
314+
def kraus_identity_check(kraus: Sequence[Gate]) -> None:
191315
r"""Check identity of a single qubit Kraus operators.
192316
193317
:Examples:
194318
195319
>>> cs = resetchannel()
196-
>>> tc.channels.single_qubit_kraus_identity_check(cs)
320+
>>> tc.channels.kraus_identity_check(cs)
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198322
.. math::
199323
\sum_{k}^{} K_k^{\dagger} K_k = I
200324
201325
:param kraus: List of Kraus operators.
202326
:type kraus: Sequence[Gate]
203327
"""
204-
placeholder = backend.zeros([2, 2])
328+
329+
dim = backend.shape_tuple(kraus[0].tensor)
330+
shape = (len(dim), len(dim))
331+
placeholder = backend.zeros(shape)
205332
placeholder = backend.cast(placeholder, dtype=cons.dtypestr)
206333
for k in kraus:
334+
k = Gate(backend.reshape(k.tensor, [len(dim), len(dim)]))
207335
placeholder += backend.conj(backend.transpose(k.tensor, [1, 0])) @ k.tensor
208-
np.testing.assert_allclose(placeholder, np.eye(2), atol=1e-5)
336+
np.testing.assert_allclose(placeholder, np.eye(shape[0]), atol=1e-5)
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339+
single_qubit_kraus_identity_check = kraus_identity_check # backward compatibility
209340

210341

211342
def kraus_to_super_gate(kraus_list: Sequence[Gate]) -> Tensor:

‎tensorcircuit/gates.py

+15
Original file line numberDiff line numberDiff line change
@@ -47,6 +47,21 @@
4747
_yy_matrix = np.kron(_y_matrix, _y_matrix)
4848
_zz_matrix = np.kron(_z_matrix, _z_matrix)
4949

50+
_ix_matrix = np.kron(_i_matrix, _x_matrix)
51+
_iy_matrix = np.kron(_i_matrix, _y_matrix)
52+
_iz_matrix = np.kron(_i_matrix, _z_matrix)
53+
_xi_matrix = np.kron(_x_matrix, _i_matrix)
54+
_yi_matrix = np.kron(_y_matrix, _i_matrix)
55+
_zi_matrix = np.kron(_z_matrix, _i_matrix)
56+
57+
_xy_matrix = np.kron(_x_matrix, _y_matrix)
58+
_xz_matrix = np.kron(_x_matrix, _z_matrix)
59+
_yx_matrix = np.kron(_y_matrix, _x_matrix)
60+
_yz_matrix = np.kron(_y_matrix, _z_matrix)
61+
_zx_matrix = np.kron(_z_matrix, _x_matrix)
62+
_zy_matrix = np.kron(_z_matrix, _y_matrix)
63+
64+
5065
_cnot_matrix = np.array(
5166
[
5267
[1.0, 0.0, 0.0, 0.0],

‎tests/test_dmcircuit.py

+13
Original file line numberDiff line numberDiff line change
@@ -256,3 +256,16 @@ def r(key):
256256
rs1, rs2 = r(key1), r(key2)
257257
assert rs1[0] != rs2[0]
258258
assert np.allclose(rs1[1], 0.4, atol=1e-5) or np.allclose(rs2[1], 0.4, atol=1e-5)
259+
260+
261+
@pytest.mark.parametrize("backend", [lf("npb"), lf("tfb"), lf("jaxb")])
262+
def test_dep(backend):
263+
264+
cs = tc.channels.generaldepolarizingchannel(0.1, 1)
265+
tc.channels.kraus_identity_check(cs)
266+
267+
cs = tc.channels.generaldepolarizingchannel([0.1, 0.1, 0.1], 1)
268+
tc.channels.kraus_identity_check(cs)
269+
270+
cs = tc.channels.generaldepolarizingchannel(0.02, 2)
271+
tc.channels.kraus_identity_check(cs)

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