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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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# http://www.apache.org/licenses/LICENSE-2.0
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import mimiqcircuits.operations.gates.gate as mcg
import mimiqcircuits as mc
from mimiqcircuits.lazy import LazyArg, LazyExpr
from symengine import eye
from mimiqcircuits.circuit import Circuit
[docs]
class GateRNZ(mcg.Gate):
r"""
Multi-qubit parity-phase rotation gate along the Z-axis.
Applies a phase of ``e^{±i θ/2}`` depending on the parity (number of 1s) in the computational basis state.
Args:
n (int): Number of qubits
theta (float or symbolic): Rotation angle
Examples:
>>> from mimiqcircuits import *
>>> from symengine import pi
>>> GateRNZ(2, pi/2)
RNZ((1/2)*pi)
>>> GateRNZ()
lazy GateRNZ(?, ?)
>>> GateRNZ(2)
lazy GateRNZ(2, ?)
>>> GateRNZ(2, pi/2).decompose()
2-qubit circuit with 3 instructions:
├── CX @ q[0], q[1]
├── RZ((1/2)*pi) @ q[1]
└── CX @ q[0], q[1]
<BLANKLINE>
>>> c = Circuit()
>>> c.push(GateRNZ(3, pi/2), 1, 2, 3)
4-qubit circuit with 1 instructions:
└── RNZ((1/2)*pi) @ q[1,2,3]
<BLANKLINE>
"""
_name = "RNZ"
_num_bits = 0
_num_cregs = 0
_num_zregs = 0
_num_zvars = 0
_num_qregs = 1
_zregsizes = []
_cregsizes = []
_parnames = ("theta",)
def __new__(cls, *args):
if len(args) == 0:
return LazyExpr(cls, LazyArg(), LazyArg())
elif len(args) == 1:
return LazyExpr(cls, args[0], LazyArg())
elif len(args) == 2:
n, theta = args
if isinstance(n, int):
return object.__new__(cls)
raise ValueError("Invalid arguments for GateRNZ. Expected, (n, theta).")
def __init__(self, n=None, theta=None):
if not isinstance(n, int) or n <= 0:
raise ValueError("GateRNZ expects a positive integer for number of qubits.")
self._num_qubits = n
self._num_qregs = 1
self._qregsizes = [n]
self.theta = theta
def __str__(self):
return f"RNZ({self.theta})"
[docs]
def inverse(self):
return type(self)(self.num_qubits, -self.theta)
[docs]
def power(self, pwr):
return type(self)(self.num_qubits, self.theta * pwr)
[docs]
def matrix(self):
from mimiqcircuits.matrices import cis
θ = self.theta
N = self.num_qubits
dim = 1 << N
mat = eye(dim)
for i in range(dim):
parity = bin(i).count("1")
mat[i, i] = cis((-((-1) ** parity)) * θ / 2)
return mat
def _decompose(self, circ: Circuit, qtargets, ctargets=None, ztargets=None):
ancilla = qtargets[-1]
data = qtargets[:-1]
for q in data:
circ.push(mc.GateCX(), q, ancilla)
circ.push(mc.GateRZ(self.theta), ancilla)
for q in reversed(data):
circ.push(mc.GateCX(), q, ancilla)
return circ
[docs]
def evaluate(self, d):
"""
Evaluate symbolic parameters with substitution dictionary d.
Args:
d (dict): Mapping of symbolic variables to values.
Returns:
GateRNZ: A new evaluated GateRNZ instance.
"""
theta = self.theta
if hasattr(theta, "subs"):
theta = theta.subs(d)
return type(self)(self.num_qubits, theta)
__all__ = ["GateRNZ"]
