Shift of quantum critical point of discrete time crystal on a noisy quantum simulator

Recent advances in quantum technology have enabled the simulation of quantum many-body systems on real quantum devices. However, such quantum simulators are inherently subject to decoherence, and its impact on system dynamics - particularly near quantum phase transitions - remains insufficiently understood. In this work, we experimentally investigate how decoherence in quantum devices affects the dynamics of quantum time crystals, using a 156-qubit IBM Quantum system. We find that decoherence shifts the location of critical behavior associated with the phase transition, suggesting that noisy simulations can lead to inaccurate identification of phase boundaries. Our results underscore the importance of understanding and mitigating decoherence to reliably simulate quantum many-body systems on near-term quantum hardware.