Possible mechanisms for life near absolute 0

Question

The overview:
Would any form of complex life be possible near absolute 0? At least for my personal standards, the "life" merely has to be:

• a self-sustaining,
• self-replicating machine,
• with a "computer" / brain,
• that doesn't necessarily need to be cellular.

The goals:
To optimize my search I have 2 tier-lists of goals based on what turns out to be realistically possible for both "mechanism" and "temperature", with the bare minimum for "mechanism" being artificially replicated metallic robots, and the highest tier being a possibly cellular, organic lifeform that automatically reproduces, heals, grows, and thinks sapiently. While the tier-list for "temperature" would preferably be as close to absolute 0 as realistically possible with reality's exact unaltered laws, and at least as cold as any possible complex computer can exist at, even if artificially constructed.

The solvent, if any:
My first thought was for the beings to be very similar to robots, taking advantage of the almost non-existent temperatures for a brain comprised of a quantum computer, but then I realized these beings would probably have to be built manually, which is acceptable, but is of lower priority than a cellular and self-constructing design, if that turns out to be realistically possible.
I then studied the basic mechanisms of cellular life and came to the possibly eroneous conclusion that complex cellular life would require a solvent to transport various resources, yet apparently only helium remains liquid at near absolute 0. This led me to studying for literally multiple hours, trying to find any information on the material solubility of liquid helium, on which I found almost nothing 😅 aside from the vague statement that "helium is a noble element and reacts with very little."

The energy / food source(s):
As for energy, my current best idea is for the lifeforms to derive energy from some sort of nuclear reaction, as both solids and 'apparently' radiation can easily exist near absolute 0, and the best specific reaction I've found so far would be the reaction of "free radicals" oxidizing pyrite into "sulfate" (whatever that is) and apparently iron oxide, although from what I've read, the iron oxide couldn't be used to build material or "flesh", so sadly it may be largely wasted as excrement.

The current ideas:
This brings me to my current best 2 ideas for possible complex life at absolute 0:

• At best? A cellular creature that somehow has access to and swallows radioactive uranium, pyrite, and possibly some form of construction material based in carbon like calcium or proteins, deriving energy from the radiation/pyrite-derived sulfate, and repairing and growing tissue with the carbon or silicon or "whatever".
  If possible, it circulates liquid helium through its body to transport nutrients, and either simply never excretes this helium, or drinks helium from natural reserves in its environment.
  It would move around either by rolling using its spherical form occasionally pushed by two thick trunk-like arms, each with minimal surface contact with the icy ground, or by walking on two legs optimized for minimal surface contact with the icy ground.

• At medium: a similar self-replicating cellular lifeform at some higher temperature, whatever turns out to be the lowest possible temperature to harbor complex self-replicating life.

• At worst: simply an artificial robot with a quantum computer "brain", living off of nuclear reactions.

Answer 1

Purely electromagnetic.

For all practical purposes chemistry does not happen at 0. But electromagnetism definitely happens.

https://en.wikipedia.org/wiki/Persistent_current

In superconductors, charge can flow without any resistance. It is possible to make pieces of superconductor with a large built-in persistent current, either by creating the superconducting state (cooling the material) while charge is flowing through it, or by changing the magnetic field around the superconductor after creating the superconducting state.[1] This principle is used in superconducting electromagnets to generate sustained high magnetic fields that only require a small amount of power to maintain...

Your creatures are comprised solely of persistent current cells flowing in their superconducting substrate. Growth and reproduction of these creatures takes place via electromagnetic manipulation of the molecules of the substrate, rearranging them in patterns favorable for growth and development of these electrical creatures. Of course such creatures would feed on electricity, arranging for naturally occurring charge differences to be added to their own perpetual current loop.

I can imagine a "field" of such creatures, their substrate having been arranged and rearranged with the generations into overlapping geometric crystalline patterns. Charge harvesting spicules protrude into the overlying vacuum to collect charge. Perhaps periodic storms bring dust or debris allowing the electrical creatures to conduct up and out of their substrate, and establish colonies elsewhere on their world.

Shout out to the classic scifi A pail of air and its memorable portrayal of a frozen earth.

He wasn't just making up those ideas. Odd things happen in a world that's about as cold as can be, and just when you think matter would be frozen dead, it takes on a strange new life. A slimy stuff comes crawling toward the Nest, just like an animal snuffing for heat—that's the liquid helium. And once, when I was little, a bolt of lightning—not even Pa could figure where it came from—hit the nearby steeple and crawled up and down it for weeks, until the glow finally died.