Princeton University

School of Engineering & Applied Science

Fast Control by a Quantum Actuator

Professor Paola Cappellaro, Massachusetts Institute of Technology
Tuesday, March 31, 2015 - 12:00pm

Fast and high fidelity control of quantum systems is a key ingredient for quantum computation and sensing devices. The critical task is to reliably control a quantum system, while staving off decoherence, by keeping it isolated from any external influence. These requirements pose a contradiction: fast control implies a strong coupling to an external controlling system, but this entails an undesired interaction with the environment, leading to decoherence.
A strategy to overcome these issues is to use a hybrid system where a quantum actuator interfaces the quantum system of interest to the classical controller, thus allowing fast operations while preserving the system isolation and coherence. This indirect control is particularly appropriate for nuclear spin qubits, which only couple weakly to external fields, but often show strong interactions with nearby electronic spins. In this talk I will describe a strategy to achieve time-optimal indirect control of a nuclear spin qubit by an electronic spin quantum actuator. In particular, I will consider the specific case of the NV center in diamond with applications to both control and sensing.