On-Demand Directional Photon Emission with Waveguide Quantum Electrodynamics

Aziza Almanakly | Bharath Kannan | Youngkyu Sung | David Rower | David Kim | Alexander Melville | Bethany Niedzielski | Mollie Schwartz | Jonilyn Yoder | Terry Orlando |Joel Wang | Jeffrey Grover | Simon Gustavsson | William Oliver

The ability to distribute and communicate quantum information between distinct processing nodes is a key requirement towards realizing a fully connected network of quantum processors. This communication is either mediated by photons that propagate between the nodes, or by a bus coupler that coherently couples adjacent nodes. However, the communication fidelity of protocols involving propagating photons are often limited by the need for chiral components with large insertion losses, such as circulators. Alternatively, while protocols that use bus couplers between nodes do not require such components, they are generally restricted to nearest-neighbor connectivity. Here, we strongly couple qubits to a bi-directional waveguide and leverage the quantum interference between their emissions to generate photons that selectively propagate in a single direction. This architecture and protocol eliminates the need for lossy circulators between nodes, and the devices can be tiled in series to form a network of quantum processors with all-to-all connectivity.

Funding Sources: This research was funded in part by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under contract no. DE-AC02-05-CH11231 within the High-Coherence Multilayer Superconducting Structures for Large Scale Qubit Integration and Photonic Transduction program (QISLBNL); and by the Under Secretary of Defense for Research and Engineering under Air Force Contract No. FA8702-15-D-0001. A.A. acknowledges support from the PD Soros Fellowship program. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the U.S. Government.