Comment by mikepfrank
5 days ago
I have concerns about density & cost for both photonic & superconductive computing. Not sure what one can do with quantum Hall effect.
Regarding long-term returns, my view is that reversible computing is really the only way forward for continuing to radically improve the energy efficiency of digital compute, whereas conventional (non-reversible) digital tech will plateau within about a decade. Because of this, within two decades, nearly all digital compute will need to be reversible.
Regarding bypassing the Landauer limit, theoretically yes, reversible computing can do this, but not by thermally cooling anything really, but rather by avoiding the conversion of known bits to entropy (and their energy to heat) in the first place. This must be done by "decomputing" the known bits, which is a fundamentally different process from just erasing them obliviously (without reference to the known value).
For the quantum case, I haven't closely studied the result in the second paper you cited, but it sounds possible.
/? How can fractional quantum hall effect be used for quantum computing https://www.google.com/search?q=How+can+a+fractional+quantum...
> Non-Abelian Anyons, Majorana Fermions are their own anti particles, Topologically protected entanglement
> In some FQHE states, quasiparticles exhibit non-Abelian statistics, meaning that the order in which they are braided affects the final quantum state. This property can be used to perform universal quantum computation
Anyon > Abelian, Non Abelian Anyons, Toffoli (CCNOT gate) https://en.wikipedia.org/wiki/Anyon#Abelian_anyons
Hopefully there's a classical analogue of a quantum delete operation that cools the computer.
There's no resistance for electrons in superconductors, so there's far less waste heat. But - other than recent advances with rhombohedral trilayer graphene and pentalayer graphene (which isn't really "graphene") - superconductivity requires super-chilling which is too expensive and inefficient.
Photons are not subject to the Landauer limit and are faster than electrons.
In the Standard Model of particle physics, Photons are Bosons, and Electrons are Leptons are Fermions.
Electrons behave like fluids in superconductors.
Photons behave like fluids in superfluids (Bose-Einstein condensates) which are more common in space.
And now they're saying there's a particle that only has mass when moving in certain directions; a semi-Dirac fermion: https://en.wikipedia.org/wiki/Semi-Dirac_fermion
> Because of this, within two decades, nearly all digital compute will need to be reversible.
Reversible computing: https://en.wikipedia.org/wiki/Reversible_computing
Reverse computation: https://en.wikipedia.org/wiki/Reverse_computation
Time crystals demonstrate retrocausality.
Is Hawking radiation from a black hole or from all things reversible?
What are the possible efficiency gains?