5 ms·

VW Solves Quantum Chemistry Problems on a D-Wave Machine

88 points by saligne 8y ago

Havoc 8y ago
>For beginners, he says, an actual D-Wave device isn’t even necessary. I find this somewhat surprising. If you think of AI code designed for GPUs, there I can see "yeah you can practice on a CPU". It'll suck but it'll work. For quantum tech the entire sales pitch is that it's fundamentally different...doing what's near impossible on conventional hardware. Yes I realise he's talking about the library so annealing on a CPU I guess but still seems like a very strange comment in this context.
- zaroth 8y ago
  I think the performance of the actual device is so limited it’s like running an iPhone simulator to debug your software. But if the expected performance of the quantum machine is theoretically going to increase exponentially every X months for the next 2 decades, combined with the theory that certain problems shift from exponential to polynomial time solutions, yes, eventually the “debugger” will not be useful to actually try running your solver.
  - jcoffland 8y ago
    But quantum computing performance hasn't increased exponentially in the last X months.
- ben_w 8y ago
  If I understand correctly (which is a big if given it is quantum mechanics), any quantum algorithm can be stimulated on a non-quantum computer, but doing so has an exponential penalty.
  - lisper 8y ago
    Exactly right.
- empath75 8y ago
  Everything I’ve read says that the d-wave isn’t a real quantum computer.
  - archgoon 8y ago
    This is basically correct. When people talk about "Quantum Computers" that can factor large primes, they are referring to a Universal Gate Quantum Computer. As of today, the largest Universal Gate Quantum Computer has 72 qubits. The DWave Quantum Annealers are essentially a special purpose device that performs Quantum Annealing. What they refer to as 'Qubits' are very different from the entangled Qubits of a Universal Quantum Computer. To the best of my knowledge (and the paper explicitly distinguishes between the two types), it has yet to be demonstrated that Quantum Annealing is equivalent to Universal Gate Quantum Computer (and is generally suspected not to be), is in it's own complexity class, or even if it provides any complexity speedup over classical computers.
    - garmaine 8y ago
      There isn’t a universal quantum computer in the sense that there is a universal Turing machine for classical computation. All quantum computers are special purpose circuits, not general logic machines.
      - deleted 8y ago
        [deleted]
- krastanov 8y ago
  "Quantum tech" is regrettably much too overloaded of a term. The "quantum annealers" that D-Wave sells are not known to be more powerful than classical computers. For the moment, at best, they are interesting analog computers. Quantum computers (either the circuit model or equivalently the quantum adiabatic computer model) are conjectured to be much more powerful than classical computers, but they are quite a bit different from D-Wave's quantum annealers (for starters, they are supposed to be able to keep all their qubits in a pure entangled state, which D-Wave definitely can not do). There are various experimental hardwares that are able to keep a handful of qubits entangled, but we will need thousands (if not millions) before being able to do anything useful with them.
zaroth 8y ago
I appreciated the rudimentary presentation of the capabilities and limitations of the machine and calling out the connectivity of the qubits versus a universal quantum machine which would have full connectivity between all the bits. I’d be curious is there a simple formula for calculating the “effective universal qubits” of the D-Wave? 2,048 indeed sounds like a lot of qubits based on my extremely limited knowledge of quantum, but with only ~6k connections versus fully connected which would be n(n-1)/2 = ~2mil is it just a marketing gimmick? Why is it useful to push the bit count so high if the connectivity is so limited?
- klyrs 8y ago
  I don't know of a good way to compare their real-valued gates to complex gates; it's probably a scaling factor due to encoding those gates as gadgets. As for full connectivity; this is a benefit over gate-model: they can simulate fully-connected logical qubits; on the order of 2sqrt(Q/2), or 64, in their existing hardware. As for the high bit count: sparse, structured problems can make very good use of the existing connectivity. Simulations of a cubic lattice are nearly competitive with modern classical hardware, for example. IIRC they can factor 16-bit numbers, too --these problems are "quasiplanar" and have relatively low connectivity requirements. Full connectivity actually brings some huge engineering challenges; DWave's strategy is more about "this is what's actually possible today" and not "we're going to make universal quantum computers, don't ask us about error correction or crosstalks or calibration of large-scale microwave circuits"
- tbabej 8y ago
  It's important to note here that the current gate-based quantum processors also suffer from the connectivity problems. It's not just annealers suffering. In those architectures, the limited connectivity enforces usage of SWAP gates, which increases the circuit depth. Circuit depth, with imperfect qubits and gates, is currently the limiting factor - we don't have practical error-correction for the chips of today's size. Hence one can only perform a certain number of operations before his computation decoheres and becomes useless.
twtw 8y ago
... and couldn't get the correct answers for LiH. Interesting that the article didn't mention this. From the paper: > For lithium hydride, LiH, we were not able to reproduce closely the ground state energy with the currently available hardware. When accounting for 3 orbitals and using a scaling factor of r = 4, we already had to use 1558 qubits, which is a large fraction of available qubits. To summarize: the investigated method in general works, but it might be difficult to apply it to larger systems.
- jf- 8y ago
  Presumably because that’s just a matter of scale. The calculation didn’t turn out wrong, the machine just isn’t powerful enough to calculate it. All of this work is proof of concept for more powerful devices down the road, the point isn’t that it’s better than a classical computer right now.
  - williamscales 8y ago
    Is there any evidence it will ever be better than a classical computer?
    - FeepingCreature 8y ago
      For the record, the concept is called Quantum Supremacy [1]. So far, there is no demonstration of quantum supremacy, but it seems like it may just be a matter of time. [1] https://en.wikipedia.org/wiki/Quantum_supremacy https://en.wikipedia.org/wiki/Quantum_supremacy
      - deleted 8y ago
        [deleted]
      - stochastic_monk 8y ago
        It’s related, but quantum supremacy is about asymptotic speedups rather than actual speed differences. Additionally, it’s worth keeping in mind that D-Wave machines aren’t true quantum computers in the sense that they can’t perform Grover’s or Shor’s algorithms.
iamgopal 8y ago
VW also does science ? Nice to know. Is it related to battery technology etc ? Or such companies usually invest in fundamental research ?
- iamlucaswolf 8y ago
  They do. As an annecdote, the professor who formerly held the "Machine Learning" course at TU Munich left for VW's AI research group (https://argmax.ai https://argmax.ai) a few years ago. Whether that qualifies as "science" may be debatable, but the larger players in the automotive space are definitely invested in this kind of research.
- ams6110 8y ago
  They do. These days, battery chemistry is probably very interesting to them. Earlier, it would have been problems such as optimizing combustion chamber shape, etc.
- jlg23 8y ago
  From the article: His group’s paper runs down a wish list of quantum chemistry simulations that sufficiently robust quantum computation should be able to tackle. Such problems include designing next-generation batteries, optimizing solar cells via detailed study of photosynthesis, and faithfully simulating complex molecules without resorting to approximations that conventional computers must rely on to make the simulations tractable.
- jonstewart 8y ago
  They’re expert at hiding emissions results, among other things.
- delecti 8y ago
  Quantum computing is also of interest to self-driving cars. I know that at least some other big car companies do quantum computing work for that reason. I wouldn't be surprised if this is a test of sorts.
crb002 8y ago
Curious to see Aaronson's criticism.
- jackfraser 8y ago
  Aaronson is unfortunately in a sunk-cost position when it comes to D-Wave - he's been so against them for so long that even if they start to produce good results his bias is going to make it difficult for him to fairly evaluate them, especially if it means reaching different conclusions about their past work than he did previously. Probably better to look to other commentators on this one, at least until he has enough time to emotionally process the situation and come around to it. It's not so easy admitting you're wrong in the shtetl.
  - Dylan16807 8y ago
    Your first paragraph is fine. But your second says "process the situation and come around to it" as if they've already proven anything. Nobody has ever seriously claimed that the machine can't calculate things. Proof of it doing a calculation doesn't change the status quo.
- _Nat_ 8y ago
  I kinda doubt anyone's going to really criticize this one. I mean, the controversy about D-Wave (if I recall correctly) was largely related to claims about it having achieved [quantum advantage over classical computing methods](https://en.wikipedia.org/wiki/Quantum_supremacy https://en.wikipedia.org/wiki/Quantum_supremacy), along with misunderstandings about what kind of "quantum computer" it is. However, it's generally accepted that D-Wave is a working computer that uses quantum models; that fact's uncontroversial. In this paper, they reported using that uncontroversial ability to perform optimization problems to optimize some physics problems. And it worked basically as-expected.
martinlaz 8y ago
The paper: https://arxiv.org/abs/1811.05256 https://arxiv.org/abs/1811.05256
AlexCoventry 8y ago
What's the business motivation of this research, for VW?
- pas 8y ago
  Batteries? Fuel efficiency? Better catalytic emission filter?
  - B1FF_PSUVM 8y ago
    Better cheating? Although they're already pretty successful at that, the dieselgate thing cost them some money, but none of the executives in charge of the fraud is in jail or financially punished. ["How VW Paid $25 Billion for 'Dieselgate' – and Got Off Easy" - https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal ]
    - blattimwind 8y ago
      https://en.wikipedia.org/wiki/Defeat_device#Timeline https://en.wikipedia.org/wiki/Defeat_device#Timeline https://en.wikipedia.org/wiki/Diesel_emissions_scandal https://en.wikipedia.org/wiki/Diesel_emissions_scandal
    - jhayward 8y ago
      > none of the executives in charge of the fraud is in jail or financially punished. This is nothing relevant to the article, it's just ad-hominem attacks, and factually incorrect at that. The very wiki page you cite says that CEO Winterkorn is charged with fraud, the CEO of Audi has been arrested, and 6 executives in the US are presently under charges.
    - chillwaves 8y ago
      I love my VW GTI.
- _Nat_ 8y ago
  They probably sold it to management as exploring future simulation-and-optimization methodologies. I mean, right now, the D-Wave computers seem too weak to be worth the expense compared to classical computers. So, it seems unreasonable for them to expect near-term practicality from this sort of investigation. But in principle, if D-Wave systems greatly improve to the point that they're competitive with classical optimizers, then it'd be good for VW engineers to be able to leverage them to do stuff like, in this case, predict chemical properties. This seems to be how the article sells it: > “Our present work was a first field study of quantum chemistry problems on quantum annealing devices,” he says. “Our goal was to get a feeling for the bottlenecks of the problem. This in the end helps [us] to understand the underlying problems, and find new solutions or suitable subproblems.”
sampo 8y ago
> The researchers did not run a similar algorithm on a conventional computer system to see whether the D-Wave computation was faster.
- philipkglass 8y ago
  Standard quantum chemical methods for this sort of problem would finish in a fraction of a second on a Raspberry Pi. Calculating the ground state energy of a tiny system like LiH was tractable way back in the 1960s. I'd need to see their actual numbers to determine when a conventional computer first reached their level of accuracy on LiH but I'm sure it is several decades back. EDIT: according to the paper, the initial energy at each point was found using the Hartree-Fock method with a minimal STO-3G basis set. This is one of the simplest and oldest approaches to this sort of calculation on a conventional computer. For these starting calculations they used Psi4 [1] by way of OpenFermion [2]. For the H2 molecule, their additional DWave calculations improved the accuracy of the distance-energy curve over the baseline Hartree-Fock/STO-3G calculations. For LiH, there was no improvement (Figure 3). The total runtime of their approach was therefore that of the conventional approach plus an additional series of calculations that did not yield improvements in the case of LiH. [1] http://www.psicode.org/ http://www.psicode.org/ [2] https://github.com/quantumlib/OpenFermion https://github.com/quantumlib/OpenFermion
withhighprod 8y ago
Interesting. Did D-wave’s qubit quality get better?
nickpsecurity 8y ago
Wouldnt these potential customers of D-Wave be better off just buying a HPC cluster with lots of CPU's, GPU's, and FPGA's? Probably more opportunities for hardware reuse, too.

88 points by saligne 8y ago

>For beginners, he says, an actual D-Wave device isn’t even necessary. I find this somewhat surprising. If you think of AI code designed for GPUs, there I can see "yeah you can practice on a CPU". It'll suck but it'll work. For quantum tech the entire sales pitch is that it's fundamentally different...doing what's near impossible on conventional hardware. Yes I realise he's talking about the library so annealing on a CPU I guess but still seems like a very strange comment in this context.

zaroth 8y ago
I think the performance of the actual device is so limited it’s like running an iPhone simulator to debug your software. But if the expected performance of the quantum machine is theoretically going to increase exponentially every X months for the next 2 decades, combined with the theory that certain problems shift from exponential to polynomial time solutions, yes, eventually the “debugger” will not be useful to actually try running your solver.
- jcoffland 8y ago
  But quantum computing performance hasn't increased exponentially in the last X months.
ben_w 8y ago
If I understand correctly (which is a big if given it is quantum mechanics), any quantum algorithm can be stimulated on a non-quantum computer, but doing so has an exponential penalty.
- lisper 8y ago
  Exactly right.
empath75 8y ago
Everything I’ve read says that the d-wave isn’t a real quantum computer.
- archgoon 8y ago
  This is basically correct. When people talk about "Quantum Computers" that can factor large primes, they are referring to a Universal Gate Quantum Computer. As of today, the largest Universal Gate Quantum Computer has 72 qubits. The DWave Quantum Annealers are essentially a special purpose device that performs Quantum Annealing. What they refer to as 'Qubits' are very different from the entangled Qubits of a Universal Quantum Computer. To the best of my knowledge (and the paper explicitly distinguishes between the two types), it has yet to be demonstrated that Quantum Annealing is equivalent to Universal Gate Quantum Computer (and is generally suspected not to be), is in it's own complexity class, or even if it provides any complexity speedup over classical computers.
  - garmaine 8y ago
    There isn’t a universal quantum computer in the sense that there is a universal Turing machine for classical computation. All quantum computers are special purpose circuits, not general logic machines.
    - deleted 8y ago
      [deleted]
krastanov 8y ago
"Quantum tech" is regrettably much too overloaded of a term. The "quantum annealers" that D-Wave sells are not known to be more powerful than classical computers. For the moment, at best, they are interesting analog computers. Quantum computers (either the circuit model or equivalently the quantum adiabatic computer model) are conjectured to be much more powerful than classical computers, but they are quite a bit different from D-Wave's quantum annealers (for starters, they are supposed to be able to keep all their qubits in a pure entangled state, which D-Wave definitely can not do). There are various experimental hardwares that are able to keep a handful of qubits entangled, but we will need thousands (if not millions) before being able to do anything useful with them.

zaroth 8y ago

I appreciated the rudimentary presentation of the capabilities and limitations of the machine and calling out the connectivity of the qubits versus a universal quantum machine which would have full connectivity between all the bits. I’d be curious is there a simple formula for calculating the “effective universal qubits” of the D-Wave? 2,048 indeed sounds like a lot of qubits based on my extremely limited knowledge of quantum, but with only ~6k connections versus fully connected which would be n(n-1)/2 = ~2mil is it just a marketing gimmick? Why is it useful to push the bit count so high if the connectivity is so limited?

klyrs 8y ago
I don't know of a good way to compare their real-valued gates to complex gates; it's probably a scaling factor due to encoding those gates as gadgets. As for full connectivity; this is a benefit over gate-model: they can simulate fully-connected logical qubits; on the order of 2sqrt(Q/2), or 64, in their existing hardware. As for the high bit count: sparse, structured problems can make very good use of the existing connectivity. Simulations of a cubic lattice are nearly competitive with modern classical hardware, for example. IIRC they can factor 16-bit numbers, too --these problems are "quasiplanar" and have relatively low connectivity requirements. Full connectivity actually brings some huge engineering challenges; DWave's strategy is more about "this is what's actually possible today" and not "we're going to make universal quantum computers, don't ask us about error correction or crosstalks or calibration of large-scale microwave circuits"
tbabej 8y ago
It's important to note here that the current gate-based quantum processors also suffer from the connectivity problems. It's not just annealers suffering. In those architectures, the limited connectivity enforces usage of SWAP gates, which increases the circuit depth. Circuit depth, with imperfect qubits and gates, is currently the limiting factor - we don't have practical error-correction for the chips of today's size. Hence one can only perform a certain number of operations before his computation decoheres and becomes useless.

twtw 8y ago

... and couldn't get the correct answers for LiH. Interesting that the article didn't mention this. From the paper: > For lithium hydride, LiH, we were not able to reproduce closely the ground state energy with the currently available hardware. When accounting for 3 orbitals and using a scaling factor of r = 4, we already had to use 1558 qubits, which is a large fraction of available qubits. To summarize: the investigated method in general works, but it might be difficult to apply it to larger systems.

jf- 8y ago
Presumably because that’s just a matter of scale. The calculation didn’t turn out wrong, the machine just isn’t powerful enough to calculate it. All of this work is proof of concept for more powerful devices down the road, the point isn’t that it’s better than a classical computer right now.
- williamscales 8y ago
  Is there any evidence it will ever be better than a classical computer?
  - FeepingCreature 8y ago
    For the record, the concept is called Quantum Supremacy [1]. So far, there is no demonstration of quantum supremacy, but it seems like it may just be a matter of time. [1] https://en.wikipedia.org/wiki/Quantum_supremacy https://en.wikipedia.org/wiki/Quantum_supremacy
    - deleted 8y ago
      [deleted]
    - stochastic_monk 8y ago
      It’s related, but quantum supremacy is about asymptotic speedups rather than actual speed differences. Additionally, it’s worth keeping in mind that D-Wave machines aren’t true quantum computers in the sense that they can’t perform Grover’s or Shor’s algorithms.

iamgopal 8y ago

VW also does science ? Nice to know. Is it related to battery technology etc ? Or such companies usually invest in fundamental research ?

iamlucaswolf 8y ago
They do. As an annecdote, the professor who formerly held the "Machine Learning" course at TU Munich left for VW's AI research group (https://argmax.ai https://argmax.ai) a few years ago. Whether that qualifies as "science" may be debatable, but the larger players in the automotive space are definitely invested in this kind of research.
ams6110 8y ago
They do. These days, battery chemistry is probably very interesting to them. Earlier, it would have been problems such as optimizing combustion chamber shape, etc.
jlg23 8y ago
From the article: His group’s paper runs down a wish list of quantum chemistry simulations that sufficiently robust quantum computation should be able to tackle. Such problems include designing next-generation batteries, optimizing solar cells via detailed study of photosynthesis, and faithfully simulating complex molecules without resorting to approximations that conventional computers must rely on to make the simulations tractable.
jonstewart 8y ago
They’re expert at hiding emissions results, among other things.
delecti 8y ago
Quantum computing is also of interest to self-driving cars. I know that at least some other big car companies do quantum computing work for that reason. I wouldn't be surprised if this is a test of sorts.

crb002 8y ago

Curious to see Aaronson's criticism.

jackfraser 8y ago
Aaronson is unfortunately in a sunk-cost position when it comes to D-Wave - he's been so against them for so long that even if they start to produce good results his bias is going to make it difficult for him to fairly evaluate them, especially if it means reaching different conclusions about their past work than he did previously. Probably better to look to other commentators on this one, at least until he has enough time to emotionally process the situation and come around to it. It's not so easy admitting you're wrong in the shtetl.
- Dylan16807 8y ago
  Your first paragraph is fine. But your second says "process the situation and come around to it" as if they've already proven anything. Nobody has ever seriously claimed that the machine can't calculate things. Proof of it doing a calculation doesn't change the status quo.
_Nat_ 8y ago
I kinda doubt anyone's going to really criticize this one. I mean, the controversy about D-Wave (if I recall correctly) was largely related to claims about it having achieved [quantum advantage over classical computing methods](https://en.wikipedia.org/wiki/Quantum_supremacy https://en.wikipedia.org/wiki/Quantum_supremacy), along with misunderstandings about what kind of "quantum computer" it is. However, it's generally accepted that D-Wave is a working computer that uses quantum models; that fact's uncontroversial. In this paper, they reported using that uncontroversial ability to perform optimization problems to optimize some physics problems. And it worked basically as-expected.

martinlaz 8y ago

The paper: https://arxiv.org/abs/1811.05256 https://arxiv.org/abs/1811.05256

AlexCoventry 8y ago

What's the business motivation of this research, for VW?

pas 8y ago
Batteries? Fuel efficiency? Better catalytic emission filter?
- B1FF_PSUVM 8y ago
  Better cheating? Although they're already pretty successful at that, the dieselgate thing cost them some money, but none of the executives in charge of the fraud is in jail or financially punished. ["How VW Paid $25 Billion for 'Dieselgate' – and Got Off Easy" - https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal https://en.wikipedia.org/wiki/Volkswagen_emissions_scandal ]
  - blattimwind 8y ago
    https://en.wikipedia.org/wiki/Defeat_device#Timeline https://en.wikipedia.org/wiki/Defeat_device#Timeline https://en.wikipedia.org/wiki/Diesel_emissions_scandal https://en.wikipedia.org/wiki/Diesel_emissions_scandal
  - jhayward 8y ago
    > none of the executives in charge of the fraud is in jail or financially punished. This is nothing relevant to the article, it's just ad-hominem attacks, and factually incorrect at that. The very wiki page you cite says that CEO Winterkorn is charged with fraud, the CEO of Audi has been arrested, and 6 executives in the US are presently under charges.
  - chillwaves 8y ago
    I love my VW GTI.
_Nat_ 8y ago
They probably sold it to management as exploring future simulation-and-optimization methodologies. I mean, right now, the D-Wave computers seem too weak to be worth the expense compared to classical computers. So, it seems unreasonable for them to expect near-term practicality from this sort of investigation. But in principle, if D-Wave systems greatly improve to the point that they're competitive with classical optimizers, then it'd be good for VW engineers to be able to leverage them to do stuff like, in this case, predict chemical properties. This seems to be how the article sells it: > “Our present work was a first field study of quantum chemistry problems on quantum annealing devices,” he says. “Our goal was to get a feeling for the bottlenecks of the problem. This in the end helps [us] to understand the underlying problems, and find new solutions or suitable subproblems.”

sampo 8y ago

> The researchers did not run a similar algorithm on a conventional computer system to see whether the D-Wave computation was faster.

philipkglass 8y ago
Standard quantum chemical methods for this sort of problem would finish in a fraction of a second on a Raspberry Pi. Calculating the ground state energy of a tiny system like LiH was tractable way back in the 1960s. I'd need to see their actual numbers to determine when a conventional computer first reached their level of accuracy on LiH but I'm sure it is several decades back. EDIT: according to the paper, the initial energy at each point was found using the Hartree-Fock method with a minimal STO-3G basis set. This is one of the simplest and oldest approaches to this sort of calculation on a conventional computer. For these starting calculations they used Psi4 [1] by way of OpenFermion [2]. For the H2 molecule, their additional DWave calculations improved the accuracy of the distance-energy curve over the baseline Hartree-Fock/STO-3G calculations. For LiH, there was no improvement (Figure 3). The total runtime of their approach was therefore that of the conventional approach plus an additional series of calculations that did not yield improvements in the case of LiH. [1] http://www.psicode.org/ http://www.psicode.org/ [2] https://github.com/quantumlib/OpenFermion https://github.com/quantumlib/OpenFermion

withhighprod 8y ago

Interesting. Did D-wave’s qubit quality get better?

nickpsecurity 8y ago

Wouldnt these potential customers of D-Wave be better off just buying a HPC cluster with lots of CPU's, GPU's, and FPGA's? Probably more opportunities for hardware reuse, too.