Comment by dgfl
5 hours ago
This is a pipe dream and I’m almost tempted to say a fever dream. The chemistry part seems somewhat sound, even though that’s outside of my field of expertise. But the entire readout process is questionable, and has clear signs of heavy AI writing.
The AFM mechanism described as “tier 1” (very strong LLMism, btw) is somewhat optimistic but realistic. The fields needed are large compared to usual values in solid state devices, but I’d guess achievable with an AFM. But “tier 2” is vague and completely speculative. Some random things I noted: - handwaving that (not exact quote) “the read controller is cached. No need to read the same bit twice”. Cached with what?? If this miraculous technology can achieve 25 PB/s, what can possibly hope to cache it? More generally, it’s a strange thing to point out. - some magic and completely handwaved MEMS array that converts an 8um spot size laser beam into atomic-resolution 2D addressing? In my opinion this is the biggest sin of the manuscript. What I understood to be depicted is just fundamentally physically impossible. - a general misunderstanding of integrated electronics, and dishonest benchmarking, comparing real memory technologies being sold at scale right now, vs theoretical physical bounds on an untested idea. Also no mention of existing magnetic tape as far as I can tell. - constantly pulling out specific numbers or estimates with no citation and insufficient justification. Too many examples to even count.
I’m sorry for the harsh language, I wouldn’t use it for a usual review. But in my opinion this needs a very heavy toning down and complete rewrite, and is unfit for a proper review. Final remark: electronics is, and will always fundamentally be, intrinsically denser than optics. Some techniques “described” here, if they were possible, would have been applied to existing optical tech (i.e. phase change materials in blue-ray).
Yes, this paper is insane. The actual quote about caching is:
> Once a region of tape has been read, the controller stores the result. Subsequent operations reference the cache rather than re-interrogating the physical medium. Re-reading a known bit is unnecessary; the controller already holds its state
However, earlier, the paper claims:
> The transformer architectures underpin- ning modern large language models are bandwidth-limited, not compute-limited [1–3]. The energy consumed moving data between DRAM, NAND flash, and processor cache already exceeds the energy consumed by arithmetic in datacenter AI accelerators [2]. This is not an optimization problem. It is a materials problem [emphasis mine].
as part of a longer rant about the AI "memory wall" in the very first section. If we open with a long spiel about how memory is expensive in material cost and energy cost and this material is a solution for that then what are we caching the read in? On that note, what kind of computer engineer thinks about cache on the order of individual bits on a medium?
And, as you point out, 25 PB/s is a lot. Around 1000x that of a typical on-die SRAM cache, I think.
A while later, the author speaks of using atomic force microscopy to read the data back. The size of AFM scans are, in practice, as I understand, along the order of square micrometers. I think this whole paper is an AI-driven, as you put it, 'fever dream', enabling an author to put forth 60 pages of sciencey claims and sciencey math without -- as far as I can tell -- any concrete and novel scientific result of any kind. AI-driven reality warps are not new; the difference is nowdays AIs are good enough at sounding smart to get past the barriers of a typical smart person who might want to be fooled or make a show of being open-minded. Later on, the author proposes using "shaped femtosecond IR pulses" -- without further elaboration -- to address single atoms! IR wavelengths are on the order of a micrometer at minimum!
Author here. Some fair points, some misreadings.
The caching comment refers to the Tier 1 controller holding a bitmap of bits it has already scanned — standard practice in any scanning probe system. It's not competing with the storage medium for capacity.
Tier 2 is explicitly labeled speculative. The paper's validation target is Tier 1: one C-AFM scan, one voltage pulse, existing equipment.
The core contribution is not the architecture — it's the physics: a verified transition state for C-F pyramidal inversion at 4.6 eV (B3LYP) and 4.8 eV (CCSD(T)), one imaginary frequency, barrier below bond dissociation. That's standard computational chemistry, not handwaving. The architecture sections are forward-looking by design.
The fluorine passes between two carbon neighbors through a C-C gap of 2.64 Å at the transition state — not through any atom. This is pyramidal inversion, the same mechanism as ammonia, but with a 4.6 eV barrier instead of 0.25 eV.
Magnetic tape comparison is in Table 2.
Dude, you _have_ to write things in your own words if you want to be taken seriously. "The <x> is not <y> — it's <z>" will cause a bunch of people to disengage, and those people have high overlap with the people who may fund you.