Quantum walking via superconducting circuit quantum electrodynamics

The quantum walk is the quantum analogue to the ubiquitous random walk in Physics and has recently yielded efficient quantum algorithms for decision trees. We show how a quantum walk, with a single walker and controllable decoherence, can be implemented for the first time by using a quantum quincunx created in superconducting circuit quantum electrodynamics (QED). Two resonators are employed to provide simultaneously fast readout and controllable decoherence over a wide range of parameters, and the Hadamard coin flip is achieved by directly driving the cavity.