Abstract:
We demonstrate the realization of continuous time crystals (CTCs) in semiconductors through the dissipative many-body electron-nuclear spin system. A CTC represents the spontaneous and persistent breaking of translational symmetry in time, manifested here as robust limit-cycle dynamics over an extensive range of parameters, including laser power, temperature, and magnetic field. Remarkably, the coherence time of these periodic oscillations, reflective of the ideal ordering of "time atoms" within the CTC, is limited only by the measurement time and can extend for several hours. Furthermore, we observe chaotic oscillations, suggesting a "melting" of the CTC, characterized by broadening spectral density peaks and a loss of ideal time translational symmetry. These chaotic regimes yield insights into CTC dynamics, with Lyapunov exponents and correlation dimensions shedding light on this transitional phase [1].
Building on this foundation, we explore the nonlinear dynamics in this electron-nuclear spin system (ENSS) when periodically driven. We observe parametric resonances by modulating external parameters—such as excitation power and pump polarization—signaling a transition from continuous to discrete time crystal (DTC) behavior [2]. Key phenomena include frequency entrainment and Arnold tongues, where the system’s oscillations lock to the modulation frequency with tunable width based on polarization depth. Outside entrainment, fractional subharmonic responses create bifurcation jets and a devil’s staircase in the frequency spectrum, culminating in a chaotic transition as the system nears an entrainment range.
These findings reveal the ENSS's versatility as a testbed for studying nonequilibrium matter and nonlinear systems, deepening our understanding of synchronized and chaotic dynamics. By bridging theoretical predictions and experimental realizations, this work has broad implications for both fundamental physics and applications in semiconductor technologies.
[1] A. Greilich et al., Nat. Phys. 20, 631 (2024), https://doi.org/10.1038/s41567-023-02351-6
[2] A. Greilich et al., arXiv:2406.06243v1 (2024)
****
Upcoming IQP events:
Nov 20, Hendrik Weimer(TU Berlin)
Nov 27, MPSD! Michael Buchhold (U Köln), MPSD seminar room!
Dec 3, Tue! Hossein Sadeghpour (ITAMP)
Dec 11, Peter Schauss (IQP)
Jan 22, Kyung Choi (Q-Block)