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Robust Oscillations and Edge Modes in Nonunitary Floquet Systems
Vikram Ravindranath1, Xiao Chen1
1Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA.
Physical Review Letters
|June 24, 2023
Summary
We discovered a new oscillatory phase in driven spin chains using measurement and postselection. This phase exhibits a unique real edge mode, stable against interactions and disorder.
Area of Science:
- Quantum mechanics
- Condensed matter physics
- Spin systems
Background:
- Periodically driven spin chains are a key area of research in quantum many-body physics.
- Weak measurement and postselection offer novel ways to probe quantum states.
Purpose of the Study:
- To investigate the oscillatory behavior in periodically driven spin chains under weak measurement and postselection.
- To understand the underlying mechanisms and characteristics of the observed oscillatory phase.
Main Methods:
- Utilizing a combination of theoretical analysis and numerical simulations.
- Mapping the spin chain models to free fermion models to analyze spectral properties.
- Investigating the stability of the oscillations against perturbations like interactions and disorder.
Main Results:
- A clear transition to an oscillatory phase was identified as measurement strength increased.
- The transition corresponds to the opening of a gap in the imaginary direction of the spectrum.
- A robust, purely real, edge pi mode was discovered in the oscillatory phase, linked to the complex bulk spectrum.
Conclusions:
- The study reveals a novel oscillatory phase in driven spin chains, characterized by unique spectral properties and edge modes.
- The findings highlight the role of measurement and postselection in driving quantum phase transitions.
- The discovered edge mode and its stability suggest potential applications in robust quantum information processing.
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