Observation of a Temporal Topological Interface State in a Parametric Oscillator
ORAL
Abstract
Topological concepts have revolutionized phononics, enabling robust wave transport in structured media [1]. Recently, attention has shifted to phononic time crystals, where material properties are modulated in time. A key challenge, however, is the experimental realization of topological phenomena in such systems, which often require complex lattice architectures.
We demonstrate the direct observation of a Temporal Topological Interface State [2] in a compact, single-degree-of-freedom magneto-mechanical system. This state is an excitation sharply localized in time, emerging at the boundary between two temporal modulation sequences. Our approach eliminates the need for a physical lattice, showing that topological features can be encoded entirely in the time evolution of a single oscillator.
The experiment uses a custom magneto-mechanical oscillator: a pendulum whose stiffness is parametrically controlled via non-contact magnetic forces. These forces are produced by synchronized, motor-driven permanent-magnet arrays, enabling precise, programmable modulation of its dynamics in real time. To generate the topological interface, we apply two sequential harmonic modulation protocols with different topological invariants (Zak phases).
At the instant the system switches from the first protocol to the second—the temporal interface—we observe the emergence of a sharply localized resonance, providing clear experimental evidence of a Temporal Topological Interface State. By realizing this phenomenon in a tunable magneto-mechanical system, our work opens a path to compact, time-programmable phononic devices for advanced vibration control.
References:
1. Mousavi, S. Hossein, Alexander B. Khanikaev, and Zheng Wang. "Topologically protected elastic waves in phononic metamaterials." Nature communications 6.1 (2015): 8682.
2. Lustig, Eran, Yonatan Sharabi, and Mordechai Segev. "Topological aspects of photonic time crystals." Optica 5.11 (2018): 1390-1395.
We demonstrate the direct observation of a Temporal Topological Interface State [2] in a compact, single-degree-of-freedom magneto-mechanical system. This state is an excitation sharply localized in time, emerging at the boundary between two temporal modulation sequences. Our approach eliminates the need for a physical lattice, showing that topological features can be encoded entirely in the time evolution of a single oscillator.
The experiment uses a custom magneto-mechanical oscillator: a pendulum whose stiffness is parametrically controlled via non-contact magnetic forces. These forces are produced by synchronized, motor-driven permanent-magnet arrays, enabling precise, programmable modulation of its dynamics in real time. To generate the topological interface, we apply two sequential harmonic modulation protocols with different topological invariants (Zak phases).
At the instant the system switches from the first protocol to the second—the temporal interface—we observe the emergence of a sharply localized resonance, providing clear experimental evidence of a Temporal Topological Interface State. By realizing this phenomenon in a tunable magneto-mechanical system, our work opens a path to compact, time-programmable phononic devices for advanced vibration control.
References:
1. Mousavi, S. Hossein, Alexander B. Khanikaev, and Zheng Wang. "Topologically protected elastic waves in phononic metamaterials." Nature communications 6.1 (2015): 8682.
2. Lustig, Eran, Yonatan Sharabi, and Mordechai Segev. "Topological aspects of photonic time crystals." Optica 5.11 (2018): 1390-1395.
*H. K. S. gratefully acknowledges Ph.D. funding of the GATE Fellowship from the Ministry of Education, Government of India. R. C. gratefully acknowledges support from the Indian Institute of Science Startup Grant.
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Presenters
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Harshit Kumar Sandhu
- Indian Institute of Science, Bangalore