Re: [Qirg] comments on the architecture principles draft
Wojciech Kozlowski <W.Kozlowski@tudelft.nl> Tue, 02 February 2021 16:19 UTC
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From: Wojciech Kozlowski <W.Kozlowski@tudelft.nl>
To: Rodney Van Meter <rdv=40sfc.wide.ad.jp@dmarc.ietf.org>, "qirg@irtf.org" <qirg@irtf.org>
CC: Rodney Van Meter <rdv@sfc.wide.ad.jp>
Thread-Topic: [Qirg] comments on the architecture principles draft
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Date: Tue, 02 Feb 2021 16:18:44 +0000
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Subject: Re: [Qirg] comments on the architecture principles draft
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I've updated the draft (on GitHub): https://github.com/Wojtek242/draft-irtf-qirg-principles/commit/16a813cbbba453d8bce284c817377d8575b5dcdc Comments in-line > -----Original Message----- > From: Qirg <qirg-bounces@irtf.org> On Behalf Of Rodney Van Meter > Sent: 21 November 2020 06:21 > To: qirg@irtf.org > Cc: Rodney Van Meter <rdv@sfc.wide.ad.jp> > Subject: [Qirg] comments on the architecture principles draft > > Wojtek, > > Some specific comments, a few requiring work and a number just > wordsmithing. > > General: > * The set of references seems to be in neither order of appearance nor > alphabetic order. I'd have to check which is more common in RFCs, > but it should be one or the other! [WK] Good point. I'm leaving this for the very final edits just before submitting as more references might be added. > > 1.: > * Not sure it's "longer-baseline" interferometry; instead it's > "higher-precision, long-baseline" interferometry [WK] Fixed > > 3.: > * "it is the transmission of qubits that draws the line between a > genuine quantum network and a collection of quantum computers > connected over a classical network." I don't fully agree with > that. The simple sharing of an entangled state does not necessarily > involve the transmission of qubits. > * "A quantum network is defined as a collection of nodes that is able to > exchange qubits and distribute entangled states amongst > themselves." and / or? [WK] In general I agree. However, the previous part of that paragraph explained how one needs to be able to transmit qubits to generate entanglement in the first place. > > 4.1.4: > * Jiang's paper also needs to be cited where Fowler's is for QEC in > communication. Jiang's paper predates Fowler, so if you can have > only one, probably Jiang, but citing both should be okay. [WK] Fixed > > 4.3: > * "This can be achieved via quantum state > teleportation." cite Charlie [WK] Fixed > * "quantum data plate" [WK] Fixed > > 4.4.1: > * how does container shipping fit into 4.4.1? [WK] From my brief skim of the paper, is it not just a 3G quantum network? > > 4.4.2: > * 4.4.2: a good opportunity to emphasize that the classical > communication is why we can't xmit useful info faster than c? [WK] Added this point, but elsewhere (together with teleportation) > > 4.4.3.1: > * "round-trip delays due to classical communication > ([17])." don't need the () [WK] Fixed > > 4.4.3.2: > * "QEC encodes a single logical qubit using many physical qubits." > generally, speaking, false. There are a lot of QEC codes that > encode multiple qubits in a block, but there are disadvantages to > this. [WK] Removed this sentence as it was there all alone and not contributing much anyway. > > 4.4.3.3: > * "small, shallow quantum circuits" -- this is the first time we've > used the term "circuit", and it's undefined. I'd recommend > rewording this to not use the term, but if you prefer you could > define it instead. [WK] Good point, fixed > * "empowered by QEC" -- an awkward phrase [WK] Fixed > * hmm, I'm not sure the 2G description here is clear enough... > (1G ande 3G seem okay) [WK] Slightly improved. Open to suggestions though as I don't have any better ideas. > > 5.1: > * "the router looks up its forwarding table" -- an awkward phrase. > Consults its forwarding table? [WK] Fixed > > 5.2: > * 5.2: I think we talked once about hard real time classical > signalling (e.g., physical-layer sync pulses) v. the slightly > softer real time operations concerning operations such as > distillation and swapping. Should this distinction be mentioned > here? [WK] I think this is best left to more concrete documents. Last time this question was raised there was a fear that this will go down a rabbit-hole of trying to define hard real time and soft real time > > 5.3.2: > * "automated quantum nodes" -- what are these? e.g., entangled photon > pair sources that don't need any inbound, classical digital > messages? Maybe we should say so. I don't _think_ a Bell state > analyzer (BSA) counts here, does it? [WK] It does say in the definition that it's a quantum repeater though... I did rephrase it slightly to hopefully be clearer. > > 5.4.3: > * "important distinctions in how errors will > be managed, as described in Section 4.4.3.3, which affects" > s/affects/affect/ [WK] Fixed > Also, maybe reference Shota's interoperability paper here? [WK] Actually forgot about this - I'll push it in a separate commit in a moment so remind me if that commit isn't there when you read this. > > 5.5.1: > * "demonstrated, but these qubits were not yet connected" > --> demonstrated for qubits not connected [WK] Fixed > * Maybe also worth commenting here again about the importance of > planet-wide RTT, compared to intra-laboratory connections? [WK] Didn't see how to meaningfully add this > Also, does this need to be "as of 2020"? [WK] Fixed > > 5.5.2: > * "A fast repetition rate for Bell pair generation is > achievable, but only a small fraction will succeed." > First, that's only true for some link architectures. Second, it's a > little confusing. How about > "Repetition rate for entanglement creation attempts is a technology- > and link-dependent factor; many link architectures are limited to > link-level round-trip time signalling for each attempt using each > memory qubit. Some link architectures allow faster attempts not > regulated by link RTT. As of 2020, all technologies have very low > success probabilities." > Too wordy? [WK] Agreed that it didn't sound very good. After scratching my head how to merge your suggestion into the text I realised it's just better off without this sentence at all. > > 5.5.3: > * "using a subset of its available qubits" -- delete "its". > A little later, add a comma after "In particular" [WK] Fixed > > 6.: > * "As this is a completely new..." it's a new paragraph, so "this" has > no antecedent. [WK] Fixed > > 6.1: > * "For example, QKD" -- goes on to talk about its relationship to Bell > pairs, but this obscures the relationship to single-photon QKD. > Maybe just add "For example, entanglement-based QKD" [WK] Fixed > * "It should not be > constrained due to considerations for early-stage hardware and > applications." No clear antecedent for "it". [WK] Fixed > > 6.2: > * "Time is part of the service" -- I was thinking that high-precision > timestamping is part of the service, especially for sensor uses, > although authenticated timestamps for certain actions could be part > of some cryptographic protocols, as well. But I don't see this > mentioned here; instead, this section is mostly about trying to be > timely to improve performance and fidelity. [WK] Upon rereading, I rephrased the paragraph, but it is about performance and fidelity though. Timestamping sounds way more concrete than desirable in this draft. > * "Second, it should not..." again, no findable antecedent for "it". [WK] fixed > > After Sect. 7, comparison with classical networks, the draft kind of ends > without any sort of conclusion. Should we have a summing up of some kind? > Personally, I find it very tempting to list the set of things that would need to > be decided to have a complete architecture, but a "work item list" doesn't > belong in an RFC. [WK] I actually like ending on this comparison. But you are right it feels like it doesn't have a conclusion. So I slightly rephrased the introduction and title to that last section to make that a conclusion. To me it is a rather creative way of saying "hey, here's what an architecture could look like" which is better than just a bullt point list > > I kept an eye on two of the concerns I keep expressing: does all-optical fit in, > and what about container shipping links? I still think it should be tweaked a > bit to accommodate them, but I don't think there are any show stopper > reasons to hold up the document if I don't figure out how add them. [WK] As I see it, if there's nothing in the draft to stop them there's no need to explicitly accommodate them. Though, I'm no expert on all-optical though so cannot really say. Containers sound like 3G quantum repeaters. But we should also remember, that this is not a document proposing a concrete architecture so if, down the line, some incompatibility is found, I don't think that would be the end of the world. Anyway, open to proposals, but I won't be working on this point myself. > > I have not yet tried to compare to the use cases draft. [WK] I believe they're mostly in-line barring some control plane fixup I pushed in the next commit so they should be aligned now. > > Rodney Van Meter > rdv@sfc.wide.ad.jp > Professor, Faculty of Environment and Information Studies, Keio University, > Japan > > _______________________________________________ > Qirg mailing list > Qirg@irtf.org > https://urldefense.proofpoint.com/v2/url?u=https- > 3A__www.irtf.org_mailman_listinfo_qirg&d=DwICAg&c=XYzUhXBD2cD- > CornpT4QE19xOJBbRy- > TBPLK0X9U2o8&r=xRe3k8UnFVGCjuC7RWUARpslGfYlRaP7D3dVZXHUEVc&m > =t1J1c2DukwzFx0VKZsbsSAQtWA_JaMcLWsXvypBL3vs&s=IdBw7Tsn6yJmlpn > 3WtQs_7JjLvjV4B2dX2AcgbWzxtw&e=
- [Qirg] comments on the architecture principles dr… Rodney Van Meter
- Re: [Qirg] comments on the architecture principle… Wojciech Kozlowski
- Re: [Qirg] comments on the architecture principle… Wojciech Kozlowski
- Re: [Qirg] comments on the architecture principle… Rodney Van Meter
- Re: [Qirg] comments on the architecture principle… Wojciech Kozlowski