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Published on: April 24, 2018
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Out-of-Time-Ordered Crystals and Fragmentation.
1Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
Physical Review Letters
|March 25, 2022
Summary
A new study explores perpetual time reversal in quantum systems. Researchers identified "out-of-time-ordered" (OTO) crystals that exhibit perpetual quantum scrambling, potentially reversing the arrow of time.
Area of Science:
- Quantum Mechanics
- Statistical Physics
- Condensed Matter Physics
Background:
- The arrow of time and irreversibility are fundamental concepts in physics.
- Out-of-time-ordered correlators (OTOCs) are key indicators of quantum scrambling and the arrow of time.
- Understanding conditions for perpetual time reversal in many-body systems remains an open question.
Purpose of the Study:
- To investigate the possibility of spontaneous, perpetual reversal of the arrow of time in many-body quantum systems.
- To determine if spatially ordered, perpetual out-of-time-ordered correlator (OTOC) oscillations can exist.
- To identify novel quantum systems exhibiting these properties, termed "out-of-time-ordered" (OTO) crystals.
Main Methods:
- Developed a rigorous lower bound for OTOC oscillation amplitudes using a local dynamical algebra.
- Identified criteria for systems exhibiting perpetual OTOC oscillations and Hilbert space fragmentation.
- Analyzed the stability of these phenomena under local unitary and dissipative perturbations.
Main Results:
- Established a novel local dynamical algebra that rigorously identifies OTO crystals.
- Demonstrated that OTO crystals, signaling perpetual quantum scrambling, require more than few-body dynamics.
- Showed that the Creutz ladder serves as a physical realization of an OTO crystal, perpetually reversing its arrow of time.
Conclusions:
- OTO crystals represent a novel state of matter exhibiting perpetual reversal of the arrow of time.
- The identified algebra and its stability ensure the robustness of OTO crystals against perturbations.
- This work opens new avenues for exploring fundamental questions about time's directionality in quantum mechanics.
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