Measuring the Adiabatic Non-Hermitian Berry Phase in Feedback-Coupled Oscillators

Singhal, Yaashnaa; Martello, Enrico; Agrawal, Shraddha; Ozawa, Tomoki; Price, Hannah M.; Gadway, Bryce

doi:10.48550/arxiv.2205.02700

Cited by 3 publications

(3 citation statements)

References 49 publications

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“…In higher dimensions, the skin effect has been shown to appear as long as the energy spectrum covers areas rather than curves [42], which is typically the case. Some unique NH phenomena have been observed in various experimental platforms, including but not restricted to mechanical [43][44][45][46][47][48], optical or photonic [49][50][51][52][53][54][55][56][57][58][59][60], atomic [61][62][63][64], and electric or superconducting circuit [65][66][67] systems…”

Section: Introductionmentioning

confidence: 99%

Bound states and photon emission in non-Hermitian nanophotonics

Gong¹,

Bello²,

Malz³

et al. 2022

Preprint

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We establish a general framework for studying the bound states and the photon-emission dynamics of quantum emitters coupled to structured nanophotonic lattices with engineered dissipation (loss). In the singleexcitation sector, the system can be described exactly by a non-Hermitian formalism. We have pointed out in the accompanying letter [Gong et al., arXiv:2205.05479] that a single emitter coupled to a one-dimensional non-Hermitian lattice may already exhibit anomalous behaviors without Hermitian counterparts. Here we provide further detail on these observations. We also present several additional examples on the cases with multiple quantum emitters or in higher dimensions. Our work unveils the tip of the iceberg of the rich non-Hermitian phenomena in dissipative nanophotonic systems.

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Section: Introductionmentioning

confidence: 99%

Bound states and photon emission in non-Hermitian nanophotonics

Gong¹,

Bello²,

Malz³

et al. 2022

Preprint

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show abstract

“…The concept of the geometric phase can be generalized to non-Hermitian systems, providing a geometrical description of the quantum evolution of non-Hermitian systems under a cyclic variation of the parameters [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72]. Compared to Hermitian systems, different forms of Berry phases have been introduced.…”

Section: Introductionmentioning

confidence: 99%

Complex Berry phase and imperfect non-Hermitian phase transitions

Longhi

Feng

2023

Phys. Rev. B

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In many classical and quantum systems described by an effective non-Hermitian Hamiltonian, spectral phase transitions, from an entirely real-energy spectrum to a complex spectrum, can be observed as a non-Hermitian parameter in the system is increased above a critical value. A paradigmatic example is provided by systems possessing parity-time (PT ) symmetry, where the energy spectrum remains entirely real in the unbroken PT phase while a transition to complex energies is observed in the broken PT phase. Such spectral phase transitions are universally sharp. However, when the system is slowly and periodically cycled, the phase transition can become smooth, i.e., imperfect, owing to the complex Berry phase associated to the cyclic adiabatic evolution of the system. This remarkable phenomenon is illustrated by considering the spectral phase transition of the Wannier-Stark ladders in a PT -symmetric class of two-band non-Hermitian lattices subjected to an external dc field, revealing that a nonvanishing imaginary part of the Zak phase-the Berry phase picked up by a Bloch eigenstate evolving across the entire Brillouin zone-is responsible for imperfect spectral phase transitions.

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“…exceptional points [51][52][53] or spectral singularities [54][55][56], at the critical point. The concept of geometric phase can be generalized to non-Hermitian systems, providing a geometrical description of the quantum evolution of non-Hermitian systems under cyclic variation of parameters [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72]. As compared to Hermitian systems, different forms of Berry phases have been introduced.…”

Section: Introductionmentioning

confidence: 99%

Complex Berry phase and imperfect non-Hermitian phase transitions

Longhi¹,

Li²

2023

Preprint

View full text Add to dashboard Cite

In many classical and quantum systems described by an effective non-Hermitian Hamiltonian, spectral phase transitions, from an entirely real energy spectrum to a complex spectrum, can be observed as a non-Hermitian parameter in the system is increased above a critical value. A paradigmatic example is provided by systems possessing parity-time (PT ) symmetry, where the energy spectrum remains entirely real in the unbroken PT phase while a transition to complex energies is observed in the unbroken PT phase. Such spectral phase transitions are universally sharp. However, when the system is slowly and periodically cycled, the phase transition can become smooth, i.e. imperfect, owing to the complex Berry phase associated to the cyclic adiabatic evolution of the system. This remarkable phenomenon is illustrated by considering the spectral phase transition of the Wannier-Stark ladders in a PT -symmetric class of two-band non-Hermitian lattices subjected to an external dc field, unraveling that a non-vanishing imaginary part of the Zak phase -the Berry phase picked up by a Bloch eigenstate evolving across the entire Brillouin zone-is responsible for imperfect spectral phase transitions.

show abstract

Measuring the Adiabatic Non-Hermitian Berry Phase in Feedback-Coupled Oscillators

Cited by 3 publications

References 49 publications

Bound states and photon emission in non-Hermitian nanophotonics

Bound states and photon emission in non-Hermitian nanophotonics

Complex Berry phase and imperfect non-Hermitian phase transitions

Complex Berry phase and imperfect non-Hermitian phase transitions

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