Preprint here:

https://arxiv.org/abs/2307.12008

Companion paper here with description of synthesis:

https://arxiv.org/abs/2307.12037

Update 2023-08-05:

Updating to answer some more common questions. If anything here differs from the 2023-07-27 update, this update should supersede that one. I believe what I have written below maintains the spirit of the market and preserves its predictivity against weird edge cases.

Materials Impurities:

This question is specifically about LK-99. In the absence of overwhelming expert consensus (see below about resolution caveats), adding materials not in the original synthesis or characterization (replacing Cu with Au, Ag, etc) will not count toward a YES resolution. 

Removing impurities (like CuS) is OK.

Increasing impurities that were also present in LK-99 original XRD is OK, up to a point. I think I would be more accepting of this is it’s convincingly shown that the impurities are important to the superconductivity of LK-99. 

Synthesis of LK-99 by other means is totally fine, as long as the material characterization satisfies the criteria above. 

Superconductivity:

The original intent of this market was to bet on whether LK-99 exhibited the hallmarks of traditional superconductivity, but there have been a few questions on what happens if LK-99 is regions of 1D superconductivity in an insulating matrix, so it doesn’t display the expected R = 0 behavior below Tc. 

At this point, I’m going to hew to the original resolution criteria, in order of importance. 

Demonstration of:

1. Meissner effect

2. R = 0 below Tc (satisfied by electric field < 0.1 - 1 uV/cm or resistivity < ~10^-11 Ohm*cm)

3. Phase change

While superconductor-insulator transitions have been observed, I’m not really familiar with them. Additionally, we don’t have good evidence that it is impossible to observe R=0 in LK-99, since at least some measurements show decreasing resistivity as a function of temperature. If we end up in a world where LK-99 convincingly displays a Meissner effect, but doesn’t show the expected resistivity behavior, I will solicit opinions from subject matter experts. After all, it would seem perverse to resolve NO if the majority of superconductivity experts think this is a YES.

Resolution Caveats:

I reserve the right to resolve to a probability if the experts I ask are split on the question of superconductivity.

I reserve the right to resolve according to whatever Wikipedia says about this material by Jan 1, 2025, especially if the experts I ask blow me off.

I reserve the right to revisit the resolution criteria if LK-99 or LK-99-like materials end up rewriting what we thought we knew about superconductivity. 

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Update 2023-07-27:

Pasting my comment on resolution criteria

We're clearly all here because a) it's fun, and b) we're interested in room temperature superconductivity, not whether some other experimental group gets the same kinda sus data as the original paper. So, when I write 'replicate' in the question I am specifically asking: is the room temperature, ambient pressure superconductivity of the compound LK-99 convincingly demonstrated?

Specifically, replications should convincingly demonstrate:

1. Zero DC electrical resistivity (or something close enough if the measurement is AC).

2. A phase change*, which is usually exhibited as a sharp discontinuity in the heat capacity.

3. The Meissner effect (magnetic fields expelled).

If synthesizing the compound, there should be evidence that they did make something essentially the same as what is reported in the original paper.

2) has an asterisk because @BenjaminShindel suggests that a phase change might not be required for a quantum well superconductor. I think I see how this could be the case. Willing to adjust this criterion after receiving more info from relevant theorists/experimentalists.

I don't intend to require that replications be published in a peer-reviewed journal. The arXiv is sufficient for me. However, I do intend to wait a few weeks/months to resolve so that any pre-print can be adequately investigated for data manipulation, fraud, etc. In my utopia, labs that claim to have confirmed/disconfirmed this effect would also publish their raw data with their arXiv submissions, but I'm not holding my breath.

Since high Tc superconductivity is not my specific field of expertise, I'm willing to defer to a consensus of subject matter experts on whether a pre-print is convincing or not, and I am willing to contact some beyond the usual twitter personalities.