Quantum walks on circles in phase space via superconducting circuit quantum electrodynamics

TL;DR

This paper demonstrates the first implementation of a quantum walk in phase space using superconducting circuit QED, showing controllable decoherence and quantum behavior over multiple steps.

Contribution

It introduces a novel method to realize quantum walks in phase space with superconducting circuits and implements controllable decoherence for interpolation.

Findings

Quantum walk implemented in superconducting circuit QED

Controllable decoherence enables transition from quantum to classical walk

Quantum walk behavior observed over 15 steps

Abstract

We show how a quantum walk can be implemented for the first time in a quantum quincunx created via superconducting circuit quantum electrodynamics (QED), and how interpolation from quantum to random walk is implemented by controllable decoherence using a two resonator system. Direct control over the coin qubit is difficult to achieve in either cavity or circuit QED, but we show that a Hadamard coin flip can be effected via direct driving of the cavity, with the result that the walker jumps between circles in phase space but still exhibits quantum walk behavior over 15 steps.