BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Andrew Lucas (University of Colorado Boulder) DTSTART:20250128T160000Z DTEND:20250128T170000Z DTSTAMP:20260423T021416Z UID:TalentQ/17 DESCRIPTION:Title: Low-density parity-check codes as stable phases of quantum matter\nby Andrew Lucas (University of Colorado Boulder) as part of Quantum Spain\n\ n\nAbstract\nPhases of matter with robust ground-state degeneracy\, such a s the quantum toric code\, are known to be capable of robust quantum infor mation storage. Here\, we address the converse question: given a quantum e rror correcting code\, when does it define a stable gapped quantum phase o f matter\, whose ground state degeneracy is robust against perturbations i n the thermodynamic limit? An affirmative answer to this question could al low us to leverage techniques from quantum error correction to learn new t hings about quantum statistical mechanics. We have proved that a low-densi ty parity-check (LDPC) code defines such a phase\, robust against all few- body perturbations\, if its code distance grows at least logarithmically i n the number of degrees of freedom\, and it exhibits a property that we ca ll "check soundness". Many constant-rate quantum LDPC expander codes have such properties\, and define stable phases of matter with a constant zero- temperature entropy density\, violating the third law of thermodynamics. O ur results also show that quantum toric code phases are robust to spatiall y nonlocal few-body perturbations.  I will conclude with potential applic ations for our ideas in condensed matter physics.\n LOCATION:https://researchseminars.org/talk/TalentQ/17/ END:VEVENT END:VCALENDAR