Quantum Control of Quantum Materials

Prof. Matteo Mitrano

Department of Physics, Harvard University, Cambridge, MA,

Coherently engineering quantum states with light is a key frontier in the control of quantum materials. Over the last two decades, ultrafast lasers have revealed a variety of emergent topological, magnetic, and superconducting states in quantum materials driven far from equilibrium. Early experiments mainly adopted incoherent excitation strategies, but more recently, resonant excitation of lattice vibrations and optical dressing of electronic states have become powerful methods to coherently drive solids by directly manipulating their microscopic Hamiltonians. Future progress hinges on demonstrating deterministic light control of quantum states, especially in systems governed by many-body interactions. In this talk, I will discuss ultrafast quantum control of a prototypical many-body quantum state—a Hubbard exciton. I will show how ultrafast lasers can induce coherent Floquet control of the many-body wavefunction between two states with opposite parity, achieving arbitrary rotations up to π/2 on the Bloch sphere. This capability paves the way for the synthesis of arbitrary target Hamiltonians and establishes a clear pathway for quantum control of quantum materials through tailored NMR-like pulse sequences. I will then discuss how these effects can be stabilized to timescales far beyond the duration of the external excitation, by coupling coherent control protocols with specific electronic symmetries to stabilize light-induced changes and generate metastable states on demand.