Add quantum phase estimation in the list of algorithms

[rochisha0]

Adding quantum phase estimation in the list of algorithms. Issue #264

[rochisha0]

@BoxiLi is there a controlled U operator in QuTiP?

[BoxiLi]

You can define a controlled gate object and add the object

qutip-qip/src/qutip_qip/operations/gateclass.py

Lines 970 to 993 in d58a82d

	class ControlledGate(Gate):
	def __init__(
	self, controls, targets, control_value, target_gate, **kwargs
	):
	super().__init__(
	controls=controls,
	targets=targets,
	control_value=control_value,
	target_gate=target_gate,
	**kwargs,
	)
	self.controls = (
	[controls] if not isinstance(controls, list) else controls
	)
	self.control_value = control_value
	self.target_gate = target_gate
	self.kwargs = kwargs
	# In the circuit plot, only the target gate is shown.
	# The control has its own symbol.
	self.latex_str = target_gate(
	targets=self.targets, **self.kwargs
	).latex_str
	def get_compact_qobj(self):

[rochisha0]

@BoxiLi this is ready for review

[BoxiLi]

Looks pretty good! Thanks a lot!

You can run black on qpe.py and test_qpe.py to clean the style. Codeclimate may have some additional complain such as trailing white space. You don't have to clean all of the code climate issues, if some of them become too tedious or irrelevant to the changes.

[BoxiLi]

There are some inconsistencies in the last change. Should be easy fix, other than that I believe this is ready to be merged.

[rochisha0]

Done @BoxiLi !

[BoxiLi]

Thanks! @rochisha0