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unnecessary high multiplication of kron space

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Daniel Tsvetkov 2019-12-04 18:03:46 +01:00
parent 5f63a19532
commit a0634208ed
1 changed files with 11 additions and 12 deletions
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23
lib_q_computer.py
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@ -80,27 +80,26 @@ def kron(_list):
class Gate(State): class Gate(State):
def on(self, state): def on(self, other_state):
""" """
Applies a gate operation on a state. Applies a gate operation on a state.
If applying to a substate, use the index of the substate, e.g. `H.on(bell[0])` will apply the Hadamard gate If applying to a substate, use the index of the substate, e.g. `H.on(bell[0])` will apply the Hadamard gate
on the 0th qubit of the `bell` state. on the 0th qubit of the `bell` state.
:param state: another state (e.g. `H.on(q1)` or a list of states (e.g. for `CNOT.on([q1, q2])`) :param other_state: another state (e.g. `H.on(q1)` or a list of states (e.g. for `CNOT.on([q1, q2])`)
:return: the state after the application of the Gate :return: the state after the application of the Gate
""" """
this_state = self.matrix_state this_state_m = self.matrix_state
if type(state) == list: if type(other_state) == list:
other_state = kron([e.matrix_state for e in state]) other_state = State(kron([e.matrix_state for e in other_state]))
else: other_state_m = other_state.matrix_state
other_state = state.matrix_state if this_state_m.shape[1] != other_state_m.shape[0]:
if this_state.shape[1] != other_state.shape[0]:
# The two arrays are different sizes # The two arrays are different sizes
# Use the Kronicker product of Identity with the state.item where # Use the Kronicker product of Identity with the state.item where
# state.item is the substate # state.item is the substate
larger_side = max(this_state.shape[1], this_state.shape[0]) larger_side = max(len(self), len(other_state))
_list = [this_state if i == state.item else _I for i in range(larger_side)] _list = [this_state_m if i == other_state.item else _I for i in range(larger_side)]
this_state = kron(_list) this_state_m = kron(_list)
return State(this_state.dot(other_state)) return State(this_state_m.dot(other_state_m))
class Qubit(State): ... class Qubit(State): ...