def measure(self, qustate_format=None):
"""Measure the QuState
Measurement of the state will result in one of the possible outcomes
with the given probability. Also, the state WILL COLLAPSE to the
outcome so this changes the state. The probability outcomes can be
checked by having an ensemble of the same states and performing a
measurement on each one. As the ensemble gets larger the probable
outcomes will match the probability amplitudes magnitude squared
"""
rand = random.random()
start = 0
index = 0
for amplitude in self.ket:
probability = measurement_probability(amplitude[0])
if start <= rand <= start + probability:
possibility = index
self._collapse(possibility)
if qustate_format == "bitstring":
return utils.int_to_bit_str(possibility, self._num_qubits)
return utils.int_to_dirac_str(possibility, self._num_qubits)
start += probability
index += 1
return None
def measure(self, qustate_format=None):
"""Measure the QuState
Measurement of the state will result in one of the possible outcomes
with the given probability. Also, the state WILL COLLAPSE to the
outcome so this changes the state. The probability outcomes can be
checked by having an ensemble of the same states and performing a
measurement on each one. As the ensemble gets larger the probable
outcomes will match the probability amplitudes magnitude squared
"""
rand = random.random()
start = 0
index = 0
for amplitude in self.ket:
probability = measurement_probability(amplitude[0])
if start <= rand <= start + probability:
possibility = index
self._collapse(possibility)
if qustate_format == "bitstring":
return utils.int_to_bit_str(possibility, self._num_qubits)
return utils.int_to_dirac_str(possibility, self._num_qubits)
start += probability
index += 1
return None
def __str__(self):
"""Dirac notation of qubit """
my_str = []
index = 0
for element in self.ket:
if element:
if my_str:
my_str.append(" + ")
my_str.append(self._amplitude_str(element[0]))
bit_str = utils.int_to_dirac_str(index, self._num_qubits)
my_str.append(bit_str)
index += 1
return "".join(my_str)
def __str__(self):
"""Dirac notation of qubit """
my_str = []
index = 0
for element in self.ket:
if element:
if my_str:
my_str.append(" + ")
my_str.append(self._amplitude_str(element[0]))
bit_str = utils.int_to_dirac_str(index, self._num_qubits)
my_str.append(bit_str)
index += 1
return "".join(my_str)
def possible_measurements(self, qubit_index=-1):
"""Returns all possible measurements and their probability.
The return value will be a map where the key is a string of the
possible state and the value is its probability of outcome. You
can return the measurement probability of a specific qubit by
using qubit_index param. Example, the third qubit of the state
1/sqrt(2)|0010> + 1/sqrt(2)|1110> can be 1 with probability 1
Args:
qubit_index: use if you want to know the possible
measurements of a specific qubit. First
qubit is 1.
Raises:
ValueError: if you specify a qubit that is out of range
"""
states_map = {}
index = 0
for element in self.ket:
if element:
probablility = measurement_probability(element[0])
dirac_str = utils.int_to_dirac_str(index, self._num_qubits)
states_map[dirac_str] = probablility
index += 1
if qubit_index >= 0:
if qubit_index > self._num_qubits:
raise ValueError("qubit_index=%s is out of range" %
str(qubit_index))
qubit_map = {}
for dirac_state in states_map:
state_index = utils.dirac_str_to_int(dirac_state)
amplitude = self._state[state_index][0]
qubit = utils.DIRAC_STR % dirac_state[qubit_index]
probablility = measurement_probability(amplitude)
if qubit in qubit_map:
old_probability = qubit_map[qubit]
qubit_map[qubit] = old_probability + probablility
else:
qubit_map[qubit] = probablility
return qubit_map
else:
return states_map
def possible_measurements(self, qubit_index=-1):
"""Returns all possible measurements and their probability.
The return value will be a map where the key is a string of the
possible state and the value is its probability of outcome. You
can return the measurement probability of a specific qubit by
using qubit_index param. Example, the third qubit of the state
1/sqrt(2)|0010> + 1/sqrt(2)|1110> can be 1 with probability 1
Args:
qubit_index: use if you want to know the possible
measurements of a specific qubit. First
qubit is 1.
Raises:
ValueError: if you specify a qubit that is out of range
"""
states_map = {}
index = 0
for element in self.ket:
if element:
probablility = measurement_probability(element[0])
dirac_str = utils.int_to_dirac_str(index, self._num_qubits)
states_map[dirac_str] = probablility
index += 1
if qubit_index >= 0:
if qubit_index > self._num_qubits:
raise ValueError("qubit_index=%s is out of range" %
str(qubit_index))
qubit_map = {}
for dirac_state in states_map:
state_index = utils.dirac_str_to_int(dirac_state)
amplitude = self._state[state_index][0]
qubit = utils.DIRAC_STR % dirac_state[qubit_index]
probablility = measurement_probability(amplitude)
if qubit in qubit_map:
old_probability = qubit_map[qubit]
qubit_map[qubit] = old_probability + probablility
else:
qubit_map[qubit] = probablility
return qubit_map
else:
return states_map