Quantum memory at nonzero temperature in a thermodynamically trivial system
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| Wydane w: | Nature Communications vol. 16, no. 1 (2025), p. 316 |
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| Wydane: |
Nature Publishing Group
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| Hasła przedmiotowe: | |
| Dostęp online: | Citation/Abstract Full Text - PDF |
| Etykiety: |
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| Streszczenie: | Passive error correction protects logical information forever (in the thermodynamic limit) by updating the system based only on local information and few-body interactions. A paradigmatic example is the classical two-dimensional Ising model: a Metropolis-style Gibbs sampler retains the sign of the initial magnetization (a logical bit) for thermodynamically long times in the low-temperature phase. Known models of passive quantum error correction similarly exhibit thermodynamic phase transitions to a low-temperature phase wherein logical qubits are protected by thermally stable topological order. Here, in contrast, we show that certain families of constant-rate classical and quantum low-density parity check codes have no thermodynamic phase transitions at nonzero temperature, but nonetheless exhibit ergodicity-breaking dynamical transitions: below a critical nonzero temperature, the mixing time of local Gibbs sampling diverges in the thermodynamic limit. Slow Gibbs sampling of such codes enables fault-tolerant passive quantum error correction using finite-depth circuits. This strategy is well suited to measurement-free quantum error correction, and may present a desirable experimental alternative to conventional quantum error correction based on syndrome measurements and active feedback.It has been commonly assumed that self-correcting quantum memories are only possible in systems with finite-temperature phase transitions to topological order. Here the authors show a complete breakdown of this expectation in quantum low-density parity-check codes. |
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| ISSN: | 2041-1723 |
| DOI: | 10.1038/s41467-024-55570-7 |
| Źródło: | Health & Medical Collection |