# Observation of tunable discrete time crystalline phases

## TL;DR

This paper reports the experimental observation of multiple discrete time crystalline phases in a nanoelectromechanical system, demonstrating their many-body nature, long-range order, and tunability via mechanical strain, advancing understanding of non-equilibrium phases.

## Contribution

It presents the first observation of multiple DTC phases in a NEMS device, showing their controllability and complex phase diagram, which broadens the scope of time crystal research.

## Key findings

- Multiple DTC phases observed in NEMS system
- Confirmation of many-body and long-range order
- Controlled phase transitions via mechanical strain

## Abstract

Discrete time crystals (DTCs) are emergent non-equilibrium phases of periodically driven many-body systems, with potential applications ranging from quantum computing to sensing and metrology. There has been significant recent interest in understanding mechanisms leading to DTC formation and a search for novel DTC phases beyond subharmonic entrainment. Here, we report observation of multiple DTC phases in a nanoelectromechanical system (NEMS) based on coupled graphene and silicon nitride membranes. We confirm the time-crystalline nature of these symmetry broken phases by establishing their many-body characters, long-range time and spatial order, and rigidity against parameter fluctuation or noise. Furthermore, we employ controlled mechanical strain to drive the transitions between phases with different symmetries, thereby mapping the emergent time-crystalline phase diagram. Overall, our work takes a step towards establishing time crystals as a system with complexity rivaling that of solid state crystals.