arXiv:2308.09559

Spontaneous Symmetry Breaking of Time-Reversal-Symmetry and Time-Crystal States in Chiral Atomic Systems

Mário G. Silveirinha, Hugo Terças, Mauro Antezza

Published Aug 18, 2023• 0 citations

Abstract

We present a theoretical study of the interaction between an atom characterized by a degenerate ground state and a reciprocal environment, such as a semiconductor nanoparticle, without the presence of external bias. Our analysis reveals that the combined influence of the electron's intrinsic spin magnetic moment on the environment and the chiral atomic dipolar transitions may lead to either the spontaneous breaking of time-reversal symmetry or the emergence of time-crystal-like states with remarkably long relaxation times. The different behavior is ruled by the handedness of the precession motion of the atom's spin vector, which is induced by virtual chiral-dipolar transitions. Specifically, when the relative orientation of the precession angular velocity and the electron spin vector is as in a spinning top, the system manifests time-crystal-like states. Conversely, with the opposite relative orientation, the system experiences spontaneous symmetry breaking of time-reversal symmetry. Our findings introduce a novel mechanism for the spontaneous breaking of time-reversal symmetry in atomic systems, and unveil an exciting opportunity to engineer a nonreciprocal response at the nanoscale, exclusively driven by the quantum vacuum fluctuations.

DOI: 10.48550/arxiv.2308.09559

Related papers

Spontaneous breaking of time-reversal symmetry and time-crystal states in chiral atomic systems

Mário G. Silveirinha, Hugo Terças, Mauro Antezza

Half-integer spin systems are characterized by a degenerate ground state. Here, the authors show that the chiral interactions of a spin-\textonehalf{} qubit with the vacuum fluctuations may spontaneously break both the time-reversal and the time-translation symmetries. In the former case, the electron spin becomes anchored along some particular direction of space determined by a geometrical symmetry. In contrast, the latter situation occurs when the intrinsic spin magnetic moment undergoes a cyclic oscillation in the ground state, realizing a time crystal.

Physical review. B./Physical review. BDec 18, 20237 citations

Chirality-induced emergent spin-orbit coupling in topological atomic lattices

Jonah S. Peter, Stefan Ostermann, Susanne F. Yelin

Spin-orbit coupling is of fundamental interest in both quantum optical and condensed matter systems alike. In this work, we show that optically induced electronic excitations in lattices of V-type atoms exhibit an emergent spin-orbit coupling when the geometry is chiral. This spin-orbit coupling arises naturally from the electric dipole interaction between the atomic sites and leads to a nontrivial topology for the lattice band structure. Using a general quantum optical model, we determine analytically the conditions that give rise to spin-orbit coupling and characterize the behavior under various symmetry transformations. We demonstrate that chirality-induced spin-orbit coupling can result from either the chirality of the underlying lattice geometry or the combination of an achiral lattice with a suitably chosen external quantization axis. We then discuss how these results are influenced by dissipation, which breaks time-reversal symmetry and illuminates the distinction between true and false chirality. Our results demonstrate that chiral atom arrays are a robust platform for realizing spin-orbit-coupled topological states of matter.

arXiv:2311.09303Physical Review AApr 23, 202410 citations

Chiral gain-induced time-reversal symmetry breaking in quantum systems

Mário G. Silveirinha, Daigo Oue

Structured light offers a powerful approach to tailor light--matter interactions in quantum systems with chiral properties. While chirality has been extensively studied in passive platforms, the role of optical gain in controlling chiral quantum dynamics remains largely unexplored. In this work, we develop a general theoretical framework to describe the dynamics of an atomic system interacting with structured gain environments, where amplification depends on the light's polarization or momentum. By quantizing the electromagnetic field in linear bianisotropic media with gain and extending the Lindblad formalism to these settings, we derive a master equation governing the atom's irreversible evolution. We show that chiral gain can break time-reversal symmetry and drive the system toward a symmetry-broken steady state with nonreciprocal properties. This effect is illustrated in detail for moving plasmonic substrates, which exhibit inherently chiral gain that selectively amplifies transitions of a given handedness. Our results establish chiral gain as a novel mechanism for engineering nonreciprocal quantum steady states.

arXiv:2505.02718Physical Review ASep 12, 20250 citations

Nonreciprocal Synchronization of Active Quantum Spins

Tobias Nadolny, Christoph Bruder, Matteo Brunelli

Active agents are capable of exerting nonreciprocal forces upon one another. For instance, one agent, say A , may attract another agent B while B repels A . These antagonistic nonreciprocal interactions have been extensively studied in classical systems, revealing a wealth of exciting phenomena such as novel phase transitions and traveling-wave states. Whether these phenomena can originate in quantum many-body systems is an open issue, and proposals for their realization are lacking. In this work, we present a model of two species of quantum spins that interact in an antagonistic nonreciprocal way of the attraction-repulsion type. We propose an implementation based on two atomic ensembles coupled via chiral waveguides featuring both braided and nonbraided geometries. The spins are active due to the presence of local gain, which allows them to synchronize. In the thermodynamic limit, we show that nonreciprocal interactions result in a nonreciprocal phase transition to time-crystalline traveling-wave states, associated with spontaneous breaking of parity-time symmetry. We establish how this symmetry emerges from the microscopic quantum model. For a finite number of spins, signatures of the time-crystal phase can still be identified by inspecting equal-time or two-time correlation functions. Remarkably, continuous monitoring of the output field of the waveguides induces a quantum traveling-wave state: a time-crystalline state of a finite-size quantum system, in which parity-time symmetry is spontaneously broken. Our work lays the foundation to explore nonreciprocal interactions in active quantum matter.

arXiv:2406.03357Physical Review XJan 21, 202541 citations

The mechanism of nuclear spontaneous time reversal symmetry breaking transfered to digital logic system

Ernest Grodner

Spontaneous time-reversal symmetry breaking in the system of an atomic nucleus is discussed on the basis of nuclear chirality phenomenon. The mechanism of nuclear chirality i.e. existence of three aplanar angular momenta vectors seems to be applicable in other fields of physics, for example in classical physics as coupling of three gyroscopes. Here, possible application of spontaneous time-reversal symmetry breaking in the design of a digital logic is discussed as an interesting curiosity.

Journal of Physics Conference SeriesSep 10, 20141 citation

Time-Crystal Particles and Classical Spin 4-vector

Mário G. Silveirinha

Time crystals are exotic phases of matter characterized by a broken time-translational symmetry, such that the ground state of the system evolves in time in a periodic fashion. Even though the time-crystal concept was introduced relatively recently, a related proposal can be traced back to Louis de Broglie. In his thesis, de Broglie conjectured that elementary particles may have some sort of internal clock that rules their behavior in the microscopic world. Here, I revisit de Broglie's idea and demonstrate that a special extreme case of classical mechanics yields in a natural way time-crystal type dynamics. Remarkably, it is found that time-crystal particles are characterized by a spin 4-vector that has a purely kinematic origin and is determined by the binormal of the velocity trajectory in the Bloch sphere. The dynamics of time-crystal particles is ruled by a generalized least action principle, such that the particle dynamically probes the nearby space and moves on average towards the direction that minimizes the action. I apply the theory to the case of charged particles and find that it predicts spin precession and that it provides a simple and intuitive picture for the origin of the anomalous magnetic moment of the electron. The classical formalism is recovered as an "effective theory" valid on a coarse time scale.

arXiv:2107.12158Jul 22, 20210 citations