Exploring Quantum Phases: From Equilibrium to the Discrete Time Crystal with Dr. Pedram Roushan

Join us today with Dr. Pedram Roushan from Google Research as we dive deep into the world of quantum many-body systems. We'll explore the fascinating phenomena of dynamical phases and the concept of discrete time crystals (DTC), revealing the wonders of out-of-equilibrium quantum systems.Nature's Non-equilibrium State:Quantum many-body systems have rich phase structures in low-temperature equilibrium states.However, nature often exists out-of-equilibrium, leading to intriguing dynamical phases not seen in equilibrium.The Novelty of Dynamical Phases:Recent predictions suggest dynamical phases might exist that are forbidden by conventional equilibrium thermodynamics.A prime example is the discrete time crystal (DTC).Understanding Eigenstate Order:Dynamical phases in periodically driven many-body-localized (MBL) systems are defined via eigenstate order.These MBL phases display quantum correlations and long-range order across the entire many-body spectrum, resulting in unique late-time dynamics.Challenges and Experimental Achievements:It's tough to differentiate stable phases from temporary phenomena in experiments.Dr. Roushan's team utilized controlled-phase (CPHASE) gates on superconducting qubits, allowing them to observe an MBL-DTC and its unique spatiotemporal response.Time-Reversal and Quantum Typicality:The team employed a time-reversal protocol to gauge external decoherence effects.Leveraging quantum typicality, they overcame the exponential challenge of sampling the eigenspectrum densely.Discovering the Phase Transition:The team identified the transition out of the DTC through a finite-size analysis, paving the way for future quantum processors.Conclusion:Dr. Pedram Roushan's groundbreaking work offers a fresh perspective on understanding quantum many-body systems and non-equilibrium phases of matter. By uncovering the mysteries of the discrete time crystal and its associated dynamical phases, we move a step closer to realizing the full potential of quantum processors.Quantum mechanics never ceases to amaze, and with pioneers like Dr. Roushan leading the way, the future of quantum research looks brighter than ever. Stay with us for the next episode, where we continue our journey into the quantum realm.https://doi.org/10.1038/s41586-021-04257-w