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Low lying excited states quantum entanglement and continuous quantum phase transitions
Yan-Chao Li1, Yuan-Hang Zhou2, Yuan Zhang2
1Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing, 100049, China. ycli@ucas.ac.cn.
Scientific Reports
|February 20, 2025
Summary
Quantum entanglement in excited states reveals quantum phase transitions beyond the standard Landau-Ginzburg-Wilson paradigm. Entanglement singularities precisely locate critical points and distinguish different phase transition types.
Area of Science:
- Condensed Matter Physics
- Quantum Information Theory
- Statistical Mechanics
Background:
- Quantum phase transitions (QPTs) are fundamental to understanding many-body quantum systems.
- The Landau-Ginzburg-Wilson (LGW) paradigm describes many QPTs but fails for some, like deconfined quantum critical points (DQCPs).
- Entanglement properties in excited states offer a novel probe for quantum phenomena.
Purpose of the Study:
- To analyze quantum phase transitions outside the LGW paradigm using entanglement in low-lying excited states.
- To investigate the role of entanglement in deconfined quantum critical points (DQCPs) in a 1D quantum spin chain.
- To differentiate between various types of Berezinskii-Kosterlitz-Thouless (BKT) phase transitions via entanglement signatures.
Main Methods:
- Analysis of entanglement in low-lying excited states of three quantum models.
- Focus on the deconfined quantum critical point (DQCP) in a one-dimensional quantum spin chain.
- Comparison of entanglement characteristics across different quantum phase transitions, including BKT transitions.
Main Results:
- A strong correlation exists between the reconstruction of low-lying excitation spectra and the DQCP.
- Singular behaviors in the entanglement of the first-excited state accurately signal the location and continuous nature of the DQCP.
- Three distinct entanglement singularity characteristics were identified when comparing DQCP with two types of BKT transitions.
Conclusions:
- Entanglement in excited states provides a powerful tool to study QPTs beyond the LGW framework.
- Entanglement singularities serve as robust indicators for critical points and can distinguish between different transition types.
- The observed entanglement features offer insights into the symmetry breaking and underlying mechanisms of various phase transitions.
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