Atomic spins are natural carriers of quantum information given their long coherence time and our capabilities to coherently control and measure them with magneto-optical fields. In this seminar I will describe two paradigms for quantum information processing with ensembles of spin in cold atoms. The strong electric dipole-dipole interactions arising when atoms are excited to high-lying Rydberg states is a powerful method for designing entangling interactions in neutral atoms. I will explore how adiabatic dressing of ground-state atoms with high-lying Rydberg states provides an avenue for further manipulation of nonclassical states based on the techniques of optimal control. By mapping a symmetrically-coupled Rydberg ensemble to the Jaynes-Cummings model, I will show how we can obtain arbitrary control of superpositions of collective Dicke states. Moreover, adiabatic dressing and quantum control can allow us to create high-fidelity entangling two-qubit gates, robust to random atomic motion at finite temperature, and other imperfections. In a second paradigm, atoms can be entangled through their mutual coupling to a common mode of the quantum electromagnetic field which acts as a quantum data bus. I will show how one can use this quantum data bus for measurement-based feedback to simulate nonlinear dynamics, quantum chaos, the quantum-to-classical transition, and quantum simulations of quantum many-body-dynamics.
Ivan Deutsch is Regents' Professor of Physics and Astronomy and the Director of the Center for Quantum Information and Control (CQuIC) at the University of New Mexico. He received his BS from MIT and his PhD in Physics from UC Berkeley, was a postdoctoral fellow at NIST with Bill Phillips, and joined the faculty at UNM in 1995. He is a theoretical physicist with interests in quantum information science and its implementation in atomic-molecular-optical systems.