Observation of a Dynamical Quantum Phase Transition by a Superconducting Qubit Simulation

Quantum information helping condensed matter research: A dynamical quantum phase transition can occur during the time evolution of a suddenly quenched quantum system, in analogy to the nonanalyticity of the free-energy density at the critical temperature of a macroscopic system. The authors succeed in observing such a transition in a quantum simulation of the quench dynamics of a many-body system. This computational experiment shows that quantum phase transitions of many-body systems can be simulated successfully using a single superconducting qubit, by varying the control parameter over the range of momenta as the qubit's spin-1/2 state evolves on the Bloch sphere.