Light pulses in a quantum walk

The principle of quantum random motion in two dimensions: At a node, a light pulse can continue on its journey through a network of optical fibres in four directions: forwards, backwards, to the right or to the left. As a quantum object, it is in fact at all the locations that are on the possible routes to a destination. Credit: MPI for the Science of Light/University of Paderborn 

Tourists who drift aimlessly during a sightseeing tour are moving randomly - just like electrons that move from one atom to the next. To obtain a better understanding of these random motions it is often useful to reduce their complexity. Physicists do this by simulating random walks. These simulations can bring new insights in the quantum world as well. Researchers at the Max Planck Institute for the Science of Light and the University of Paderborn and their colleagues are now the first to successfully realize an arrangement for a quantum walk in two dimensions. The experimental setup can be used to investigate many quantum phenomena.

in PhysOrg

Multidimensional quantum walks can exhibit highly nontrivial topological structure, providing a powerful tool for simulating quantum information and transport systems. We present a flexible implementation of a two-dimensional (2D) optical quantum walk on a lattice, demonstrating a scalable quantum walk on a nontrivial graph structure. We realized a coherent quantum walk over 12 steps and 169 positions using an optical fiber network. With our broad spectrum of quantum coins, we were able to simulate the creation of entanglement in bipartite systems with conditioned interactions. Introducing dynamic control allowed for the investigation of effects such as strong nonlinearities or two-particle scattering. Our results illustrate the potential of quantum walks as a route for simulating and understanding complex quantum systems.

in ScienceMag

 

One more victory over uncertainty in quantum physics measurements

Michael Chapman, a professor in the School of Physics at Georgia Tech, poses with optical equipment in his laboratory. Chapman’s research team is exploring squeezed states using atoms of Bose-Einstein condensates. (Credit: Gary Meek)

(PhysOrg.com) -- Most people attempt to reduce the little uncertainties of life by carrying umbrellas on cloudy days, purchasing automobile insurance or hiring inspectors to evaluate homes they might consider purchasing. For scientists, reducing uncertainty is a no less important goal, though in the weird realm of quantum physics, the term has a more specific meaning.

Watch this video to know more about The Uncertainty Principle:

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