Re: [Qirg] multiplexing?

[Bruno Rijsman <[e-mail]>]

Ah, yes, I was thinking of a more quantum-specific flavor of multiplexing: having multiple entanglements attempts going in parallel.  

If you need to do attempts sequentially (waiting for a round-trip time to receive the heralding result before starting the next attempt) entanglement generation is going to be very slow for reasonable distances.

For example, this paper https://arxiv.org/abs/1309.3202 <https://arxiv.org/abs/1309.3202> discusses spectral multiplexing where parallelism is achieved spectrally.

Or in NV centers parallelism (multiplexing) can be achieved by moving the communication qubit to a storage qubit to free up the communication qubit for the next entanglement attempt before the previous attempt was finished, i.e. before the heralding result was received (there is a paper on this, but I can’t locate it just right now).

But you are right, statistical muxing vs TDM muxing vs WDM muxing are also important considerations in quantum networks.

You need some TDM-ish clock synchronization to achieve indistinguishable photon arrivals at the heralding midpoint.  If you are also doing “parallelism” multiplexing in the sense of the start of this e-mail, then this almost inevitably leads to some sort of “time slot” concept.

And it is also often highly desirable (but not always practical) to WDM-mux the classical control channel onto the same fiber as the quantum data channel (and possibly even other classical data channels) to avoid having to use multiple fibers.

— Bruno

> On Apr 27, 2021, at 10:39 AM, Rodney Van Meter <[e-mail]> wrote:
> 
> Mmm, one problem is that it is used at many levels, and perhaps you and I are using it in different ways here.  I’m thinking of stat mux v. circuit switching, a very networky thing, but it’s also used to refer to frequency allocation in WDM and the quantum folks also use it to mean being able to connect multiple qubit memories to a single optical channel.
> 
> Rodney Van Meter
> [e-mail]
> Professor, Faculty of Environment and Information Studies, Keio University, Japan
> 
>> On Apr 27, 2021, at 17:35, Bruno Rijsman <[e-mail]> wrote:
>> 
>> I vote for updating the draft to mention multiplexing.
>> 
>> It is too important of a concept for achieving practically usable entanglement rates.
>> 
>> — Bruno
>> 
>>> On Apr 27, 2021, at 9:35 AM, Rodney Van Meter <rdv=[e-mail]> wrote:
>>> 
>>> Wojtek,
>>> 
>>> Just dinking around I noticed that we never use the word “multiplexing” in our I-D.
>>> https://datatracker.ietf.org/doc/draft-irtf-qirg-principles/
>>> We do refer to “resource management”.
>>> 
>>> QIRGers, what do y’all think?  Should we use muxing in some form in this to discuss the problem of managing access to resources along the path?
>>> 
>>> —Rod
>>> 
>>> P.S. Yes, we said in IETF a few weeks ago that this would be sent to IRSG by now, but we haven’t gotten it sent. I do think it’s ready.
>>> 
>>> Rodney Van Meter
>>> [e-mail]
>>> Professor, Faculty of Environment and Information Studies, Keio University, Japan
>>> 
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>> 
>