Physical Society Colloquium

International Year of Quantum Science and Technology

Quantum phenomena from classical light

Bill Coish

Department of Physics
McGill University

A crucial requirement for large-scale quantum information processing and quantum communication will be the development of quantum networks, with quantum information distributed at long range between nodes of stationary qubits. Most strategies for creating such a quantum network require difficult-to-realize single-photon sources and single-photon (or photon-number-resolving) detectors. I will discuss new strategies that forego these requirements by using classical (coherent state) pulses of light. These pulses can be generated from a laser, or a microwave source. The required measurements (homodyne detection) can be performed without expensive and bulky cryogenics. Entanglement distribution can then be used for quantum communication, quantum sensing, and fault-tolerant quantum computing, without the significant practical overhead associated with single-photon sources and detectors. If there is time, I will also describe how classical light in a fibre-optic cavity can be manipulated to emulate quantum condensed matter systems with a nontrivial topology or nontrivial quantum dynamics.