Spin Bath of a Central Spin System in Diamond: Polarization and Coherent Control

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

****NON-TECHNICAL ABSTRACT**** Controlling and manipulating nature at the quantum level is one of the greatest challenges facing both theoretical and experimental physics. The combination of quantum physics with information science has made possible the use of quantum systems to perform calculations and tasks of a complexity unattainable by systems that behave classically. The most important challenge facing quantum information science is to reliably control a scalable quantum system, which provides the ability to build quantum devices, while staving off decoherence (the process that leads to the loss of the quantum properties). The focus of this project is to study decoherence of a small quantum system interacting with a larger environment, whose characteristics are in part under control. The goal is to achieve a deeper physical understanding of decoherence. The ability to vary the environment's properties is critical to achieve a better understanding of decoherence, which is a complex many-body non-equilibrium quantum phenomenon. In turn, a better understanding may lead to techniques for mitigating decoherence and to improved quantum devices. The project will focus on a system, the Nitrogen-Vacancy color center in diamond, which has emerged as a highly promising quantum device for computation, magnetic sensing and bioimaging. This project will support the training of a postdoctoral fellow in an exciting and multidisciplinary research field. This research project receives support from the Division of Materials Research and the Physics Division. ****TECHNICAL ABSTRACT**** The goal of this project is to study decoherence of a central spin by a spin bath with varying and controllable characteristics. The project will focus on the electronic spin bath in diamond nano-crystals and its effects on the Nitrogen-Vacancy (NV) color center, to achieve a deeper physical understanding as well as to potentially lead to practical applications. Theoretical and experimental efforts towards a full understanding of decoherence mechanisms have been hindered by the very complexity of the dynamics. The ability to manipulate the mesoscopic bath will be exploited to perform a systematic study of the central-spin problem. Specifically, schemes for decoupling the environment from the central spin, for refocusing its internal evolution as well as for polarizing the environment spins will be developed and tested experimentally Potential applications of the control and polarization techniques range from precision measurement and bio-imaging to quantum communication and computation. For example, control and polarization of the bath would not only improve the sensitivity of recently proposed NV-based magnetic sensors, but also allow using the bath itself as a means to achieve sensitivity at the Heisenberg limit. The proposed research program will also provide interdisciplinary training of a postdoctoral fellow in condensed matter physics, nanoscience, optical imaging techniques and quantum information science, as well as in areas of potential applications, such as surface science and bioimaging. This research project receives support from the Division of Materials Research and the Physics Division.