Pressure-Quenched Superconductivity — Retention of High-Pressure States at Ambient Pressure

Thermal metastability. Pressure quenching can remove the external pressure requirement while leaving the retained superconducting phase dependent on thermal history. In Hg1223, the enhanced state degrades when warmed and can lose much of its transition-temperature enhancement after excursions above roughly 200 K. This is a structural limitation: ambient pressure alone does not establish that the quenched phase can be stored, handled, or cycled under ordinary ambient-temperature conditions.

Originating-group concentration. The cross-material evidence is stronger than a one-off observation, but the principal demonstrations are concentrated within one research programme and its collaborators. Until an unaffiliated laboratory reproduces pressure-quench retention using a published protocol, programme-specific technique, apparatus, sample preparation, or interpretation remain viable alternative explanations for the apparent generality.

Protocol and history dependence. The retained state depends on pressure magnitude, quench temperature, decompression path, defects, stoichiometry, and potentially oxygen or vacancy rearrangement. Strong path dependence can make a phenomenon physically real while still preventing reproducible transfer between laboratories or material batches. The claim therefore requires protocol-level reproducibility, not merely repeated positive samples within one experimental lineage.

Scale and recovery gap. Current demonstrations rely on very small samples processed under diamond-anvil-cell or comparable extreme-pressure conditions. Retaining a superconducting state after decompression does not yet show that useful quantities of material can be produced, recovered, processed, or incorporated into devices without erasing the metastable phase.

Independent pressure-quench replication. An unaffiliated laboratory reproduces retention of a pressure-induced or pressure-enhanced superconducting state at ambient pressure using a published pressure-quench protocol and independent material preparation. This would remove the largest current verification bottleneck and justify movement beyond VS-03.

Thermally durable retained high-Tc state. A pressure-enhanced superconducting state remains stable at ambient pressure through room-temperature handling and subsequent cooling cycles while preserving materially enhanced superconducting properties. This would distinguish pressure removal from genuinely usable ambient-condition retention and would materially change the technological significance of the claim.