Using a digital approach instead of the previous analog approach, physicists have successfully achieved universal quantum simulation in a system of trapped ions that can, in principle, simulate any physical system efficiently. The mathematical description of the phenomenon to be investigated is programmed by using a series of laser pulses to perform a quantum calculation with atoms. (Image: H. Ritsch) Two years ago, Rainer Blatt’s and Christian Roos’ research groups from the University of Innsbruck re-created the properties of a particle moving close to the speed of light in a quantum system. They encoded the state of the particle into a highly cooled calcium atom and used lasers to manipulate it. They simulated the Zitterbewegung (quivering motion) of relativistic particles, which had never before been directly observed in nature. In the current work, the mathematical description of the phenomenon to be investigated is programmed by using a series of laser pulses to perform a quantum calculation with atoms. Laser-cooled and electrically trapped calcium atoms are used as carriers of qubits. The physicists demonstrated this method in two experiments at the Institute of Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences and at the University of Innsbruck using up to 100 gates and six qubits. Christian Roos, Daniel Nigg, Rene Gerritsma, Benjamin Lanyon (L to R) and fellow colleagues realized a quantum simulator in their laboratory that can model a multitude of physical systems. (Image: University of Innsbruck) “One of the new scientific results is that interactions and dynamics can be simulated that are not even present in the quantum computer,” said Benjamin Lanyon of the IQOQI. “However, we still need a considerably higher number of quantum bits. This means that we need to be able to control and manipulate considerably more atoms — up to 40 — in the same exact way as we did in our experiment.” This research, which Lanyon believes “will be one of the most promising applications of a future quantum computer,” was published in an online issue of the journal Science. For more information, visit: www.uibk.ac.at