A key feature of quantum physics is the existence of superpositions of single and many-particle quantum states, usually referred to as quantum coherence and entanglement respectively. Famously, these aspects of quantum theory were also characterized by Einstein as “spooky” and caused him to reject many of its predictions. However, these principles are by now so well established that they have actually become tools in the growing field of quantum information science and technology to realize new paradigms for secure communication, enhanced computation, and precision sensing.
While there have been a number of demonstrations of fundamental principles using isolated atoms, ions and photons, coherent quantum control and entanglement remains experimentally challenging in robust, stable condensed matter systems. Single spins associated with defects in diamond have emerged as a promising and versatile experimental platform for exploring these challenges. They can be used as nodes in optically connected quantum networks, as sensors for magnetic imaging with sub-micron resolution, for detecting and engineering quantum states of nano-mechanical oscillators, and even as probes in biological systems. I will discuss some of the key experimental progress and future prospects along these paths.
