A quantum random walk of a Bose-Einstein condensate in momentum space

TL;DR

This paper proposes a novel implementation of a quantum random walk using a spinor Bose-Einstein condensate in momentum space, utilizing a quantum ratchet with optical lattices and microwave pulses for control and entanglement.

Contribution

It introduces a new experimental scheme for quantum walks in momentum space with Bose-Einstein condensates, enabling enhanced control and exploration of quantum dynamics.

Findings

Experimental demonstration of an optimized quantum ratchet

Simulations show precise control over quantum walk dynamics

Potential to study biases and noise effects in quantum systems

Abstract

Each step in a quantum random walk is typically understood to have two basic components; a `coin-toss' which produces a random superposition of two states, and a displacement which moves each component of the superposition by different amounts. Here we suggest the realization of a walk in momentum space with a spinor Bose-Einstein condensate subject to a quantum ratchet realized with a pulsed, off-resonant optical lattice. By an appropriate choice of the lattice detuning, we show how the atomic momentum can be entangled with the internal spin states of the atoms. For the coin-toss, we propose to use a microwave pulse to mix these internal states. We present experimental results showing an optimized quantum ratchet, and through a series of simulations, demonstrate how our proposal gives extraordinary control of the quantum walk. This should allow for the investigation of possible biases, and classical-to-quantum dynamics in the presence of natural and engineered noise.