Re: [Qirg] renewing I-Ds: comments, please!

[Patrick Gelard <[e-mail]>]

Hi

Thanks for your answers.

1/ About teleportation the feedback i have from telcom engineers :

    To be able to teleport 1 Qubit you must first :

    - generate a pair of maximally entangled qubits, referred to as EPR
    pair, with each qubit stored at each remote node.

    - consume two classical bit.

A direct transmission of Qubit does not need to consume all these 
communication resources, but you are limited by the distance unless 
quantum error correction progress significantly

Teleport a qudits (with d>> 2) should be more beneficial even if consume 
more ressources than a qubit. Because you can exploit more parallelism 
(exponential) for the calculation (more dimensions)


2/Can a set of Bell pairs be used to establish multipoint/multicast 
communication? for example, for distributed quantum computing.


/Patrick

Le 06/09/2019 à 18:05, Wojciech Kozlowski a écrit :
> Thanks for your feedback. I didn't have time to address all your 
> points, but I have some comments inline:
>
> On Wed, 2019-09-04 at 14:45 +0000, Gelard Patrick wrote:
>>
>> 2/ It is written that :
>>
>> However, it is impossible to entangle two qubits without ever having 
>> them directly interact with each other (e.g. by performing a local 
>> two-qubit gate, such as the CNOT)
>>
>> Does this sentence not contradict the paragraph “4.3.3.  Bell Pair 
>> links and entanglement swapping”   ? Because with entanglement 
>> swapping it is possible to entangle two qubits that never directly 
>> interact with each other : https://arxiv.org/abs/quant-ph/0409093 !!!
>>
>
> This is a very good point and it just shows the draft needs some extra 
> care with the language. I guess the best way to clarify this point is 
> that entanglement swapping doesn't actually create entanglement. 
> Instead one of the particles is simply teleported to a more distant 
> location. I haven't addressed this point in the latest version though.
>
>> 3/To achieve teleportation, a Bell Pair needs to be distributed 
>> between the source and destination. Thus to teleport a Qubit we need 
>> first to distributed a Bell Pair and also use two classical bit. This 
>> is not a very effective type of communication because it is consume 
>> more resource than the one is transmit, isn’t it ? !!!
>>
>
> It doesn't consume more resources, because we are not interested in 
> transmitting classical data. Qubits are teleported for the purposes of 
> sharing quantum states and entanglement (for use by higher-layer 
> applications), something you cannot do by simply transmitting 
> classical bits.
>
>
>> 4/ 5.3.1.  Goals of a quantum internet.
>>
>> -Support distributed quantum applications and Support tomorrow's 
>> distributed quantum applications. For example concerning the QKD, 
>> there is a great zoology of QKD algorithms ( 
>> https://arxiv.org/pdf/1906.01645.pdf ) not necessarily based on the 
>> same quantum phenomenon (Heisenberg's uncertainty principle, 
>> entanglement) and require different characteristic of quantum 
>> channel.   Can an internet quantum communication infrastructure take 
>> into account this diversity of needs?
>>
>
> Adding references is a pain to do in the XML format for drafts so I 
> haven't added this reference. I would also add a reference to 
> https://wiki.veriqloud.fr/index.php?title=Main_Page
>
>
>> 5/ 5.3.2.  The principles of a quantum internet.
>>
>> -Bell Pairs are the fundamental building block.Distributed quantum 
>> computation need multipartite entangled states shared among several 
>> nodes of the network and thus more than  Bell Pairs, isn’t it ? Or 
>> the goal is to transforming multipartite entangled states into the 
>> tensor product of bipartite Bell pairs between specific nodes using 
>> only a certain class of local operations and classical communication 
>> ( https://arxiv.org/abs/1907.08019 ) ?
>>
>
> I'm not sure I follow this point. You can create more complex 
> entangled states from Bell Pairs.
>
> _______________________________________________
> Qirg mailing list
> [e-mail]
> https://www.irtf.org/mailman/listinfo/qirg


---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
https://www.avast.com/antivirus