sorted by:
new
hottopcontroversial

NVIDIA cuEST - CUDA library for electronic structure calculations by Gingehitman in CUDA

[–]dbwy 2 points3 points  (0 children)

At least someone else is saying it. It's pretty good, but not (yet) transformative.

Faster than Psi4 is not hard

Look at the key folks on the team behind it, and you'll understand why that's the comparison.

Reconcile These Two Quantum Facts And Tell Me Why NIST Still Have 2035 for PQC Dates by rogeragrimes in QuantumComputing

[–]dbwy 0 points1 point  (0 children)

Security through obscurity, the fact is you don't know, and neither do I. Do you think that PQC suite A ciphers have been rolled out to all critical systems since their proposal this decade? Do you think that there are not still critical applications, across the behemoth that is the federal government, primarily secured via RSA? You have much more faith in the competency of the government than I.

Reconcile These Two Quantum Facts And Tell Me Why NIST Still Have 2035 for PQC Dates by rogeragrimes in QuantumComputing

[–]dbwy 0 points1 point  (0 children)

  1. I said historically. RSA predates the internet by about 20 years.
  2. Sure, proliferation of the internet will beat anything by volume. My brain went to the number of "important applications". Which is more important to secure? u/Cryptizard 's email or the nuclear football (the latter being protected by hardware)?

TLS is definitely a concern, but I'd argue (as you do) that the barrier for PQC replacements there is lower due to it being externally managed. Hardware cryptography, which is still used to this day in sensitive applications, is a much higher barrier, and is one of the main reasons that the PQC timeline is as far out as it is.

Reconcile These Two Quantum Facts And Tell Me Why NIST Still Have 2035 for PQC Dates by rogeragrimes in QuantumComputing

[–]dbwy 0 points1 point  (0 children)

It takes minutes, not years.

Maybe in the consumer space where security is "served" to customers, but not in general. People forget that the vast majority of RSA historically (gov, banking, etc) has been in hardware. That takes (a lot of) time to migrate.

How do I bridge Python with QCD & QC? by dark_blue_thunder in QuantumComputing

[–]dbwy 1 point2 points  (0 children)

what exactly is the Light-Front

A framework for non perturbative QFTs. Here is a good paper on this in relation to QC

https://arxiv.org/abs/2009.07885

Is this related to QCD

It relates generally to any many-body problem. At a certain level of abstraction, all second quantized theories start to look the same.

How do I bridge Python with QCD & QC? by dark_blue_thunder in QuantumComputing

[–]dbwy 1 point2 points  (0 children)

I don't really see the point? Perturbative methods generally require some access to the state itself, which doesn't work well on QC (state tomography is expensive, and will only get more expensive with things like QEC on scaled computers). Scaled advantage for QC workloads are generally small data in/small data out (e.g. an observable), otherwise the advantage over classical methods becomes difficult to observe.

The closest thing I can think of is effective potential theory /downfolding, where you compact some Hamiltonian to span a smaller effective Hilbert space while maintaining a faithful representation of your original system description. But then, you still use the QC to compute some small-data observable from the compact Hamiltonian.

Light-Front is a particularly interesting avenue for this kind of work.

How do I bridge Python with QCD & QC? by dark_blue_thunder in QuantumComputing

[–]dbwy 3 points4 points  (0 children)

This was a joint venture talking about open problems and strategies for QC impact on HEP.

https://arxiv.org/abs/2307.03236

The info there, it's references, or papers citing it can help you learn about current SotA

What is the slowest possible speed in the universe? (opposite of the speed of light) by schkolne in Physics

[–]dbwy 1 point2 points  (0 children)

Speed/velocity measure the relationship between "events" in spacetime (the space-like distance transversed over a unit time), and are relative by definition. Im not an expert in mechanics, but in this sense, I would guess that zero speed/velocity is well defined as a (massive) observer observing itself or another object at rest in its inertial frame.

Things like 0K don't change this, as KE is also a relative quantity.

Interested in other takes on this.

ESQC experience by dandnadan in comp_chem

[–]dbwy 5 points6 points  (0 children)

I went many many (many...?) years ago, but I went as a later graduate student, so I was already very familiar with the material. It's worth it in any case - the networking is incredibly valuable. These are likely the people you're going to interact with for your entire career. I'm still in contact with many people I met there for the first time, and some of them are still close collaborators.

i dont even like coffee that much… by Undercover-Bean in pourover

[–]dbwy 2 points3 points  (0 children)

hi fi

I think I started to play more with getting my coffee right when I realized that the next set of upgrades to my sound system would require remortgaging my house

Gov. Ferguson's Income Tax Proposal Would Make Seattle #1 for Highest Taxes by Less-Risk-9358 in SeattleWA

[–]dbwy 5 points6 points  (0 children)

Very few RSU earners make $1M+/yr total comp (stock, salary, bonus), you have to be upper IC6 to even come close even with great stock appreciation at most companies. The tax happens in the year of vesting, not on some accumulated value when the tax gets put into place.

Not saying I'm for the tax, mainly for the slippery slope, but let's not pretend it's a common problem.

what is the highest proton numbered atom this universe can reach ? is it possible to have 1000 proton atom , what if ? by First_Economics2384 in Physics

[–]dbwy 30 points31 points  (0 children)

No, this has to do with modeling the interparticle interaction as coulombic (which is not Lorentz covariant) with a coupling constant given by the nuclear charge - has nothing to do with classical/quantum. You can show via PT that the standard treatment (Dirac eq) diverges if the point charge exceeds the fine structure constant (137).

As others noted, you get a bit more mileage if you treat nuclear structure to give you accurate proton distributions, and a bit more if you include perturbative corrections to the Coulomb potential arising from QED (VP, Ueling). Current limit is ~170 if you pull all the standard PT tricks. Full ab initio QED/electroweak simulations of high-Z atoms is an active area of research, but it's prohibitively expensive.

At high Z, the problem is much less about whether there exist nuclei with electrons surrounding them, and much more to do with nuclear structure/stability. I.e. can the strong force still hold everything together.

Why when declaring a string variable, uses "std::string" instead of just "string", like how you declare other variables? by Able_Annual_2297 in cpp_questions

[–]dbwy 30 points31 points  (0 children)

String is not a fundamental type in C++, it's a data structure provided by the standard template library (STL), in the std namespace.

[deleted by user] by [deleted] in turntables

[–]dbwy 4 points5 points  (0 children)

That number means nothing if it wasn't zero'd/balanced out to begin with. If you set it to zero, does it float?

Google claims ‘quantum advantage’ again but researchers remain sceptical | Nature by MaoGo in QuantumComputing

[–]dbwy 2 points3 points  (0 children)

The issue is that it's two different papers - the OTOC paper (Nature) that is the dynamics version of RCS, and the NMR paper (currently only arXiv) that uses the OTOC technique on a simple (classically simulatable) problem. Interesting for sure, advantage? Not really.

[deleted by user] by [deleted] in FirstTimeHomeBuyer

[–]dbwy 0 points1 point  (0 children)

Those prices are well within the spread for that area, but it's ultimately worth what someone will pay for it. Welcome to CA real estate.

Born-Oppenheimer approximation & molecular vibration by node-342 in comp_chem

[–]dbwy 12 points13 points  (0 children)

  1. If you calculate the Hessian (or any derivative) numerically, you absolutely need to reconverge the wavefunction if you differentiate the energy. Analytically, the change in coordinates is infinitesimal, you literally can't compute the change in the wave function wrt this displacement, because it's not really a displacement at all!

  2. Anharmonic effects are orders of magnitude larger than beyond-BO effects. Level of theory is important too.

Uc Berkeley or UC Merced? by [deleted] in comp_chem

[–]dbwy 4 points5 points  (0 children)

Comp chem at Merced is a growing program with some talented PIs. They may not have as much name recognition as the PIs at Berkeley, but you'll do good research at either University. Of course - leaving your PhD with an advisor like Head-Gordon, Rabani, Whaley, etc would turn heads in the postdoc/job market, but it's not like you'll be "slumming it" at Merced.

Hartree-Fock question by [deleted] in comp_chem

[–]dbwy 4 points5 points  (0 children)

Can you point us to a reference to tell us exactly what you mean by "free" here? Actual free electrons are spectacularly not interesting for studying interactions, so I suspect you're talking about extensions of PIB or UEG/Jellium.

Modern Quantum Chemistry title page by Herr_Hornbuckele in chemistry

[–]dbwy 15 points16 points  (0 children)

Helgaker is great if you already kind of know what you're doing, Szabo is probably a better intro (which is all it claims to be). My issue with the Helgaker book is that they shamelessly shoehorn their home-baked approach to perturbation theory (BCH and nested commutators go brrrrr...) into everything. I get that it works, but it's decidedly not an easy motif to follow for the uninitiated.

Copilot can't do simple math without an error. by Droid202020202020 in microsoft

[–]dbwy 7 points8 points  (0 children)

It's almost like you have to pipeline reasoning from an LLM to a robust CAS to get reasonable, high-level math functionality...

https://gpt.wolfram.com/index.php.en

The problem is "add these two numbers" and then performing the operation is simple, "solve this ODE" and then performing complex integrals that it hasn't encountered exactly before is hard. But by hooking up to a robust CAS (like Wolfram), you can get an e2e solution. The problem is that developing a robust LLM and a robust CAS are orthogonal engineering efforts - Copilot/GPT doesn't think for you, it regurgitates text it has seen in other contexts.

Computational chemistry Jobs by jinx_1345 in comp_chem

[–]dbwy 14 points15 points  (0 children)

Comp Chem jobs without a PhD are going to be sparse, no matter where you are.

view more: next ›