start of QuantumToolboxExt

[jeffwack]

This is incomplete, but I have made some progress on #116 and have some questions. My strategy was to copy the file QuantumOpticsExt and go line by line to convert to QuantumToolbox. I ran into name collisions (basis and \otimes) come to mind, so I decided to be conservative and use the QuantumToolbox.function() form for all function calls.

I ran into a roadblock converting this:

const xyzopdict = Dict(:X=>_x, :Y=>_y, :Z=>_z)
const xyzstatedict = Dict(:X=>(_s₊,_s₋),:Y=>(_i₊,_i₋),:Z=>(_l0,_l1))
for control in (:X, :Y, :Z)
    for target in (:X, :Y, :Z)
        k1, k2 = xyzstatedict[control]
        o = xyzopdict[target]
        gate = QuantumToolbox.tensor(proj(k1),_id) + QuantumToolbox.tensor(proj(k2),o)
        structname = Symbol(control,"C",target,"Gate")
        let gate=copy(gate)
            @eval express_nolookup(::$(structname), ::QuantumToolboxRepr) = $gate
        end
    end
end

Specifically, you cannot copy() a QuantumToolbox operator. This example shows the error:

using QuantumToolbox
copy(sigmap())

So, to avoid type piracy we cannot implement the conversion as written without contributing a method for copy() to QuantumToolbox?

Another route would be to rework that chunk to avoid the copy, but I am not so clear on how it does what it does. Why the macro?

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 76.16%. Comparing base (a4980ef) to head (d903bfa).

Files with missing lines	Patch %	Lines
ext/QuantumToolboxExt/QuantumToolboxExt.jl	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #121      +/-   ##
==========================================
- Coverage   76.62%   76.16%   -0.47%     
==========================================
  Files          19       20       +1     
  Lines         830      839       +9     
==========================================
+ Hits          636      639       +3     
- Misses        194      200       +6     

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[apkille]

Specifically, you cannot copy() a QuantumToolbox operator. This example shows the error:

Could you just print the error here? It makes review and answering questions faster.

Another route would be to rework that chunk to avoid the copy, but I am not so clear on how it does what it does. Why the macro?

Notice that the for loops are iterating through Symbols. Here's a discussion on what @eval does that probably is helpful.

So, to avoid type piracy we cannot implement the conversion as written without contributing a method for copy() to QuantumToolbox?

Yeah, if you do want a new copy method for the QObjs, I would recommend submitting a PR to QuantumToolbox rather than committing type piracy here. Although that's really not necessary, there's a bunch of different ways you could define the express_nolookup methods here. To help understand what the chunk does, note how we do it in actually defining symbolic objects like (XCXGate and ZCYGate) in the source code:

QuantumSymbolics.jl/src/QSymbolicsBase/predefined.jl

Lines 119 to 132 in a4980ef

	const xyzsuplabeldict = Dict(:X=>"ˣ",:Y=>"ʸ",:Z=>"ᶻ")
	for control in (:X, :Y, :Z)
	for target in (:X, :Y, :Z)
	structname = Symbol(control,"C",target,"Gate")
	label = xyzsuplabeldict[control]*"C"*xyzsuplabeldict[target]
	declare = :(@withmetadata struct $structname <: AbstractTwoQubitGate end)
	defsymlabel = :(symbollabel(::$structname) = $label)
	instancename = Symbol(control,"C",target)
	definstance = :(const $instancename = $structname())
	eval(declare)
	eval(defsymlabel)
	eval(definstance)
	end
	end

When defining the conversion in QuantumOptics, we are looping through each permutation of the two qubit gates and lining them up with the spin operators defined in QuantumOptics.

[ytdHuang]

@jeffwack @apkille

Hi, I'm one of the developers in QuantumToolbox.jl.

For your information, we have just merged a pull request (qutip/QuantumToolbox.jl#486) to implement copy method for our quantum objects.

This will be available in our next release v0.32.0, which is scheduled maybe next week.

[ytdHuang]

@jeffwack @apkille

Just an update to you, we have released QuantumToolbox v0.32 (see our ChangeLog)

[apkille]

@jeffwack what's the status on this PR? I can help you finish it if you want.

[jeffwack]

@apkille That sounds great to me! Apologies, I let this fall off my todo list. If you want to take this over that is fine by me :)