Physics News

Atom takes a quantum walkThe Innsbruck scientists have now transferred this principle of random walk to quantum systems and stimulated an atom to take a quantum walk: "We trap a single atom in an electromagnetic ion trap and cool it to prepare it in the ground state," explains Christian Roos from the Institute of Quantum Optics and Quantum Information (IQOQI). "We then create a quantum mechanical superposition of two inner states and send the atom on a walk." The two internal states correspond to the decision of the hiker to go left or right. However, unlike the hiker the atom does not really have to decide where to go; due to the superposition of the two states, both possibilities are presented at the same time. "Depending on the internal state, we shift the ion to the right or to the left," explains Christian Roos. "Thereby, the motional and internal state of the ion are entangled." After each step the experimental physicists modify the superposition of the inner stat